Rolf Sjöström

SabA is the H. pylori hemagglutinin and is polymorphic in binding to sialylated glycans

Adherence of Helicobacter pylori to inflamed gastric mucosa is dependent on the sialic acid–binding adhesin (SabA) and cognate sialylated/fucosylated glycans on the host cell surface. By in situ hybridization, H. pylori bacteria were observed in close association with erythrocytes in capillaries and post-capillary venules of the lamina propria of gastric mucosa in both infected humans and Rhesus monkeys. In vivo adherence of H. pylori to erythrocytes may require molecular mechanisms similar to the sialic acid–dependent in vitro agglutination of erythrocytes (i.e., sialic acid–dependent hemagglutination). In this context, the SabA adhesin was identified as the sialic acid–dependent hemagglutinin based on sialidase-sensitive hemagglutination, binding assays with sialylated glycoconjugates, and analysis of a series of isogenic sabA deletion mutants. The topographic presentation of binding sites for SabA on the erythrocyte membrane was mapped to gangliosides with extended core chains. However, receptor mapping revealed that the NeuAcα2–3Gal-disaccharide constitutes the minimal sialylated binding epitope required for SabA binding. Furthermore, clinical isolates demonstrated polymorphism in sialyl binding and complementation analysis of sabA mutants demonstrated that polymorphism in sialyl binding is an inherent property of the SabA protein itself. Gastric inflammation is associated with periodic changes in the composition of mucosal sialylation patterns. We suggest that dynamic adaptation in sialyl-binding properties during persistent infection specializes H. pylori both for individual variation in mucosal glycosylation and tropism for local areas of inflamed and/or dysplastic tissue.

Helicobacter pylori adhesion to carbohydrates.

Adherence of bacterial pathogens to host tissues contributes to colonization and virulence and typically involves specific interactions between bacterial proteins called adhesins and cognate oligosaccharide (glycan) or protein motifs in the host that are used as receptors. A given pathogen may have multiple adhesins, each specific for a different set of receptors and, potentially, with different roles in infection and disease. This chapter provides strategies for identifying and analyzing host glycan receptors and the bacterial adhesins that exploit them as receptors, with particular reference to adherence of the gastric pathogen Helicobacter pylori.

A comparison of iron absorption from single meals and daily diets using radioFe (55Fe, 59Fe)

The purpose of the present study was to compare two measures of Fe absorption, one from single meals and the other from daily diets. Ten ileostomy subjects were given the same low-fibre composite diet for all three meals each day for five consecutive days. After 3 weeks the experiment was repeated with a high-fibre diet. The morning meal constituted one-seventh of the total daily diet intake, the mid-day meal two-sevenths and the evening meal four-sevenths of the total daily diet intake. On days 4 and 5 of each diet period the morning meal was labelled with 55Fe and all three meals were labelled with 59Fe. The activities retained in the subjects 19 d later showed the Fe absorption from the low-fibre diet measured from the morning meals to be almost 80% greater than the average Fe absorption measured from all meals during the same 2 d. With the high-fibre diet the absorption from the morning meals was less than 50% greater than the average for all meals but the difference was not significant. We suggest that all meals of the day should be labelled with radioFe in order to avoid inflating the measures of Fe absorption.

The effect of wheat bran on the absorption and accumulation of cadmium in rats.

1. The major purpose of the present study was to determine whether the addition of wheat bran to endosperm crisp bread in a composite diet given to rats for 6 weeks causes an increase in the accumulation of cadmium in the rats due to the Cd content in the bran, or whether binding factors in the bran, such as dietary fibre and phytic acid, reduce or prevent the accumulation of this Cd. A second purpose was to determine whether the accumulation of Cd can be estimated by measuring the absorption of 109Cd given in a single meal of the diet. 2. Three groups of eight rats were fed on one of three diets. Half of each diet consisted of a basal mixture of starch, protein, oil, minerals and vitamins. The remainder consisted of crisp breads based on refined wheat flour (endosperm group), wheat flour + bran in equal amounts (bran group) and wheat flour + Cd to give a Cd content similar to that of the bran group (endosperm + Cd group). After 41 d on the diets, the rats were deprived of food but not water for 12 h and then given a 5 g test meal of their respective diets with 109Cd added. After 3 h the remaining 109Cd-labelled diets were replaced with the unlabelled diets for 3 h before the rats were killed. 3. The total Cd contents in the wall of the proximal small intestine, including mucus, and in the liver and kidneys were highest in the endosperm + Cd group and lowest in the endosperm group.(ABSTRACT TRUNCATED AT 250 WORDS)

Cadmium accumulation from diets with and without wheat bran in rats with different iron status

Abstract The purpose of the present study was to determine to what extent the accumulation of cadmium in rats with low, marginal and high iron status is affected by the presence of bran in the diet. High iron status caused the total and fractional accumulation of cadmium from both the wheat endosperm and wheat bran diets to be decreased by almost half compared to that in the low iron status rats. The inclusion of wheat bran in the diet increased the total accumulation of cadmium in the liver by approximately the same proportion in all three iron status groups. While the results do not exclude the possibility that the availability of cadmium for absorption from wheat bran is less than that from wheat endosperm in rats with high iron status, no appreciable effect of mineral binding factors in bran on the fractional cadmium accumulation in the liver could be demonstrated in the low and marginal iron status groups. Thus, for rats with less than adequate iron status, the inclusion of wheat bran in the diet should increase the cadmium intake and its accumulation in the body by the same proportion.

The importance of the body's need for zinc in determining Zn availability in food: a principle demonstrated in the rat

1. The hypothesis that the availability of zinc in a food is limited by factors in the food was tested against the hypothesis that Zn absorption is homeostatically regulated by the body according to its need for Zn. 2. The experimental model used was the short-term administration to rats of a parenteral nutrition solution with no added Zn in an attempt to increase their need for Zn in an anabolic phase. 3. The absorption and retention of 65Zn from a piece of endosperm-wheat crisp-bread in rats injected intraperitoneally with the parenteral nutrition solution was more than 40% higher than that in a control group injected with physiological saline (9 g sodium chloride/l). 4. The results indicate that the availability of Zn in the bread is not fixed but variable and dependent on the bodys need for Zn.

The availability of zinc in endosperm, whole grain and bran-enriched wheat crispbreads fed to rats on a Zn-deficient diet

The hypothesis that factors such as dietary fibre and phytate in wheat bran limit the availability of Zn was tested in growing rats fed on low-Zn diets with different wheat crispbreads as the major source of Zn. Six groups of six weanling male rats each were fed on 5 parts semi-synthetic Zn-deficient diet and 1 part wheat-endosperm crispbread for 1 week. At the beginning of the second week, the crispbread in the diet of five groups was exchanged for crispbread made using one of the following wheat flours: (1) whole grain, (2) bran-enriched whole grain, (3) endosperm with Zn added to the whole-grain level, (4) endosperm with Zn added to the bran-enriched level, (5) whole grain with Zn added to the bran-enriched level. These diets were given ad lib. together with deionized water for 2.5 weeks. The relative absorption of Zn was lowest from the three non-supplemented diets (75-82%). All the added Zn was absorbed. As appetite, body-weight increase, Zn absorption, Zn retention and the Zn concentrations in serum and bone differed only slightly among groups fed on diets with similar Zn concentrations, it is concluded that factors such as dietary fibre or phytate in wheat bran limit the availability of Zn in wheat crispbreads very little when all the Zn is needed for growth and development in rats.

Conquer and Educate. Swedish colonialism in the Caribbean island of Saint‐Barthélemy 1784‐1878

The present paper is about the education system in Saint‐Barthélemy, a Carribean island which was a Swedish colony from 1784 to 1878. Saint‐Barthélemy was a pluralistic society where a sizeable segment of the population was of African origin. Likewise attesting to its multiplicity was the existence of three official languages, English, French and Swedish. Moreover, in a society whose population never exceeded 6,000 souls, Anglicans, Lutherans, Methodists and Roman Catholics practised their various religions. Saint‐Barthelemy was a socially‐stratified community with slaves at the lowest level. A portrait of the school system is presented with the aid of examples from comprehensive archival sources. Social control was an important function of education, especially after the liberation of the slave population, when physical control was no longer practicable. Even if the occupiers may have endeavoured to transplant Swedish educational traditions, it took a long time until the School Reform of 1842 had any palpable consequences on Saint‐Bérthelemy.

A comparative study in rats of measures of the availability of dietary zinc and iron.

The purpose of this study was to compare three measures of the availability of dietary Zn and Fe in order to test their validity. Thirtysix 5-wk-old rats were fed deionized water and wheat crispbread made from endosperm flour, whole-grain flour, or endosperm flour supplemented with Zn and Fe to the whole-grain levelsad libitum for 14 d. The retention of65Zn and59Fe from test meals of the same breads after 1 wek and the sum of the excretion of endogenous Zn and Fe (injected65Zn and59Fe) with the Zn and Fe balances, respectively, were used as independent measures of Zn and Fe absorption. Measurements of Zn absorption, Zn balance, and serum Zn concentration gave quite different results with regard to the availability of Zn in the three breads, presumably because of the homeostatic regulation of the absorption and excretion of Zn when the Zn in the diet is in excess of the body’s needs. Measurements of Fe absorption, Fe balance, and Fe concentrations in liver and serum were consistent in demonstrating overloading of Fe in the group given wheat-endosperm crispbread supplemented with Zn and Fe, but there was evidence that the isotope retention method overestimated iron absorption.

The extent of coprophagy in rats with differing iron status and its effect on iron absorption.

The purpose of this study was to determine the prevalence of coprophagy in rats with differing iron status and its effect on the measurement of iron absorption from test meals with and without bran. Two experiments were performed using radioisotope-labelled microspheres added as a non-digestible marker for the ingested faeces and the diet and 59Fe added as a marker for the non-haem iron in the test meal. In this study, coprophagy occurred at group mean rates of between 5 and 22% and was independent of the iron status of the rats or the presence or absence of bran in the diet. The relative absorption of iron, measured as the retention of 59Fe from a single meal, was affected to the same extent in groups with the same iron status, if it was affected at all. Thus comparisons of iron absorption from diets with and without bran should not be affected by coprophagy.