Endotoxicity does not limit the use of bacterial ghosts as candidate vaccines.

Gram-negative bacterial ghosts produced by controlled expression of the plasmid-encoded lysis gene E offers a promising approach in non-living vaccine technology. Bacterial cell wall complex and hence the antigenic determinants of the living cells are not affected by denaturation due to cell killing. However, the endotoxin content of the Gram-negative cell wall has been discussed as a potential problem for this kind of whole cell or envelope vaccines. Here we show that bacterial ghosts prepared from Escherichia coli O26:B6 and Salmonella typhimurium C5 induce dose-dependent antibody responses against bacterial cells or their corresponding lipopolysaccharides (LPS) in doses 25 ng kg-1 when administered intravenously to rabbits in a standard immunization protocol. No differences between the immune responses of the rabbits were observed when comparing equivalent doses of bacterial ghosts and antibiotic-treated whole cells. The results indicate that the bacterial ghosts exhibit all the antigenic properties of the living cells. No significant fever responses in rabbits have been recorded in doses of < 250 ng kg-1 E. coli O26:B6 ghosts and up to doses of 250 ng kg-1 S. typhimurium C5 ghosts when applying test methods recommended by the US pharmacopoeia. These findings correlate with cell culture experiments where doses 100 ng ml-1 of bacterial ghosts were needed for the release of tumour necrosis factor alpha (TNF alpha) and prostaglandin E2 (PGE2) from RAW mouse macrophage cultures. Free LPS of Salmonella abortus equi commonly used as a LPS-standard, however, stimulated TNF alpha and PGE2 synthesis of RAW cells in doses of 1 ng ml-1. The endotoxic activity of our bacterial preparations analysed by a standard limulus amoebocyte lysate and 2-keto-3-deoxyoctonate assay correlated with the capacity to stimulate the release of PGE2 and TNF alpha in RAW mouse macrophage cultures and the endotoxic responses in rabbits. It can be concluded that these in vitro systems can be used as easy predictive test systems for preparations of bacterial vaccines, particularly for bacterial ghosts.

[Dangers of a wrong diet in patients with renal insufficiency in the predialytic state or during chronic hemodialysis]. / Gefahren der Fehlernährung bei Patienten mit Niereninsuffzienz im prädialytischen Stadium und unter chronischer Hämodialyse

Patients with chronic renal failure and on chronic intermittent hemodialysis have several metabolic risks such as retention of urea and other products of nitrogen metabolism, catabolism, acidosis, edema, dehydration, hyper- and hypotension, hyperkalemia, renal osteopathy, and renal anemia. Uremic coma is usually avoided by balanced nutritional therapy and treatment with hemodialysis. A dietary regimen containing protein with high amounts of essential amino acids is an important part of treatment. In patients on chronic hemodialysis disorders of protein and amino acid metabolism are caused by either deficiency of essential ingredients of the food or by the metabolic defects due to chronic uremia.

Island ecology of arthropods : I. Diversity, niches, and resources on some Seychelles islands.

1. Twenty-five species of web-building spiders (Araneae) were studied by examining standard study areas on 5 islands of the Central Seychelles group that differ in size and degree of isolation. The number of individuals and of species on each island was correlated to the area, altitude, degree of isolation, and resource availability of the respective island. The effect of these factors on niche breadth and niche overlap was also examined. 2. In respect to resource availability the structural diversity of each study area was determined by means of the Shannon-Weaver formula. Environmental conditions were broken down into 4 categories according to cover, soil, water, vegetational strata, and number of plant species. In addition to this quantitative method different habitats were defined according to existing plant associations (Table 2). Both methods produced similar results. 3. As the islands increased in size, both the spectrum of resources and the number of habitats also increased. Islands of lasrger surface revealed a higher mean as well as a greater range of structural diversity (Fig. 2). Associated with the increased spectrum of resources there was a significant increase of spider species. 4. The number S of web-building spider species increases with the size A of the island according to the Wilson formula S=cA z (Fig. 3). The present study revealed the coefficient z to be remarkably low. 5. The degree of isolation of an island, calculated according to macArthur and Wilson (1967), did not explain the differing numbers of spider species on the different islands. 6. Niche breadth and niche overlap were calculated in terms of numbers of habitats and of ranges of structural diversity. The most abundant spider species had the greatest niche breadth. The average niche breadth became smaller with the increase of island size. Specific niche breadths of spiders on different islands did not vary significantly between islands (Table 6). But in all cases there was a reduced niche overlap in the more diverse spider communities (Tables 5 and 8). 7. The total density of the spider community was highest in the structurally most diversified habitats. The total density of web spiders diminished with the decreasing size of the island. The correlation between total density and number of species was significantly positive. 8. The low value of the z coefficient in the species-area relationship is discussed. The possibility of a low ecologic saturation on smaller islands is considered. Ways in which species diversity may increase are examined. Analysis of resource availability proved to be more efficient for the solution of ecologic problems than the simple examination of the species-area relationship.

Island ecology of arthropods : II. Niches and relative abundances of Seychelles ants (Formicidae) in different habitats.

1. The ant fauna of 3 islands of the Central Seychelles was studied by means of pitfall traps. The number of species and their abundances were investigated in relation to differences in island size, habitats, and microclimate conditions. In addition the effects of these factors on niche breadth and niche overlap were studied. 2. Nineteen and species were collected that belonged to 14 genera in 4 subfamilies (Table 2). Different numbers of species were found on different islands (Table 1). There are no significant correlations between the numbers of species, sizes of islands, and the available resources. The distribution of congeneric species agrees with the expected increase in 'relative diversity' on smaller islands (Fig. 3). 3. Species diversity and species distribution depend to some extent on habitat differences. This was evaluated by phytosociologic methods and microclimatic measurements. The composition of the ant fauna on different islands is more constant in undisturbed, autochthonous habitats than in those habitats that are strongly influenced by man. 4. Specific niche breadth and relative abundance of ant species showed a significantly positive correlation. Within comparable habitats, average niche breadth and niche overlap are greatest on the smallest island. Because the relative density also increases on this island, one cannot speak of a lower ecologic saturation compared with the larger islands.