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Female mice were maintained on lipid diet for 20 days. The nonspecific and immunological defense capability was determined by in vitro and in vivo methods. It was found that mice held mostly on a lipid diet demonstrate an all-round lowered response. Following 20 days of lipid diet the splenocytes exhibit: (1) an inversed lipid-protein ratio; (2) an inability to respond to sheep erythrocytes; (3) a reduction in [3H] thymidine incorporation in splenocytes stimulated with lipopolysaccharide (LPS) or with concanavalin A; (4) a reduction in the number of cells bearing surface immunoglobulins in splenocytes stimulated with LPS; (5) an inhibition of phagocytosis and intracellular killing in macrophages; (6) a lowering in granulocyte chemotaxis and adherence capacity; (7) a higher mortality to LPS after loading with galactosamine; and (8) a lowered complement activity even following LPS activation.

A study has been made of the distribution of bacterial flora in the gastro-enteric tract of rats fed on glycidic, protein and lipidic diets and compared with that found in rats given a standard diet. The flora of the gastro-enteric tract was noted in a fraction adhering to the epithelial cells of the mucous membrane and in a fraction present in the contents of the gastro-enteric tract. Changes resulting from the differences in diet are made particularly at the expense of the adhering flora. In groups fed on a glycidic diet there is a clear prevalence of enterococci, enterobacteria, lactobacilli, peptostreptococci and yeasts. In rats fed on a protein diet the quantity and variability fo the flora are less and clostridia predominate. Where rats are given a lipidic diet there is a prevalence of enterobacteria, lactobacilli and peptostreptococci. An extensive and diversified colonization is noted as a further consequence of differences in diet. The results obtained are discussed in relation to certain pathological intestinal conditions and to results reported elsewhere in the literature.

The cardiovascular effects of porins were evaluated using porins isolated from Salmonella typhimurium SH5014. In dogs porins depress arterial systemic pressure, vasomotor reactivity of norepinephrine and peripheral vagal stimulation. They are capable of modifying the sinocarotidal baroreceptor reactivity. In mice porins increase the cardiotoxic effects of isoprenaline, thyroxine, emetine and of p-nitrophenol. In rats porins increase the arrhythmogenic and lethal effects of BaCl2 and also give rise to renal lesions, probably at the tubular level.

The effect of porins purified from Salmonella typhimurium on the complement system was investigated both in vitro and in vivo. Incubation of porins with either human or guinea pig serum resulted in the consumption of the total complement activity when an amount of porins ranging from 8 to 10 micrograms per 100 microliters of serum was used. The activation of the complement system was temperature dependent, suggesting an active process rather than passive adsorption of the complement components by porins. In addition, the activation had a fast kinetic and proceeded mainly through the classical pathway. This conclusion is supported by the consumption of C1s and C4 in normal human serum treated with porins and also by the depletion of C3 activity in the C1s-deficient serum which was marked only when purified C1s was added to the serum before incubation with porins. Injection of 100 micrograms of porins into guinea pigs induced profound complement consumption at 6 h postinjection that persisted up to 12 h. We conclude from this study that porins can effectively contribute to complement activation and to subsequent biological events induced by gram-negative bacteria.

The effect of Salmonella typhimurium porins on human polymorphonuclear leukocytes (PMNs) was studied. Labeled porins were shown to bind to the PMNs, and could be completely displaced by unlabeled porins. The binding caused modifications of membrane integrity and of the physico-chemical characteristics of the PMN surface, e.g. decreased oxidative burst, decreased hydrophobicity and altered cell morphology. The porins acted as both chemotaxins and chemotaxinogens. When PMNs were preincubated with porins their migration in the presence of commonly used chemoattractants (serum activated by zymosan or N-formyl-L-methionyl-L-leucyl-L-phenylalanine) was inhibited.

The peritoneal macrophages from mice on a lipidic diet have shown an increase of surface hydrophobicity of cytoplasmatic membrane. This fact is correlated with a decrease of the phagocytic index and with an impairment of Salmonella typhimurium.

Escherichia coli K12 suspended in different media showed a loss of phospholipids. Mg2+ and Ca2+ 0.01 M prevented phospholipid loss and stabilized Escherichia coli K12 for bactericidal and bacteriolytic assays.

Major outer membrane proteins of Eikenella corrodens, an organism frequently isolated from patients with periodontal disease, were tested for some biological activities. Mouse peritoneal macrophages, exposed at low concentrations of the above-mentioned proteins (between 0.05 and 5 micrograms/ml), showed evident and marked morphological modifications consisting of increases in the size and vacuolation of the cells. Higher concentrations showed a toxic effect. Low concentrations resulted in a selective release of lysosomal enzymes without any significant release of lactatedehydrogenase, and cytoplasmic marker; while concentrations of 25-50 micrograms/ml, which were toxic in trypan-blue exclusion test, increased LDH release. Eikenella corrodens major proteins increased the platelet aggregation of ADP and thrombin. The residual complement activity of serum samples incubated with various amounts of proteins at 37 degrees C for 30 minutes appeared strongly reduced with respect to controls, thus showing a consumption of the complement components. These results suggested that Eikenella corrodens major proteins may play a role in the development of periodontal lesions.

A study was made of H(+), Na(+), K(+), Ca(++), and Mg(++) binding and ion-exchange properties of the plasma-mesosome membrane system isolated from Micrococcus lysodeikticus strain NCTC 2665. Titration curves were obtained on membranes prepared according to the method of M. R. J. Salton and further exposed to pH 4 for 4 hr (membranes-H). The dissociation coefficients and binding capacities were obtained by applying the mass law equation and the plot of G. Schatchard to the data. The membranes-H possess four kinds of dissociable groups with pK 4.96, 4.18, 3.60, and 3.09, respectively, and a total binding capacity of 0.65 meq/g (dry weight). Potentiometric titrations of cations in the presence and in the absence of membranes-H show that cations (Na(+), K(+), Ca(++), and Mg(++)) are bound by the dissociated groups of the membrane. The fall in pH value for bivalent cations is greater than that for monovalent cations. Cations of the same valency produce equal diminutions on pH. Furthermore, ion-exchange tests carried out on membranes saturated with Mg(++) or Na(+) and suspended in a medium containing (45)Ca show that the cations are reversibly bound.