Serum lysozyme increased by fructose-1, 6-diphosphate in men, rabbits, and mice.

Fructose-1, 6-diphosphate hydrated sodium salt (FDP), intravenously injected, remarkably stimulates the production of serum lysozyme in man, rabbit, and mouse with a different kinetics in each of them: Man and rabbit show, in the first hour, a concentration peak followed by a slow decrease, whereas in mouse the concentration is less variable with time.

Reticuloendothelial system activated by fructose-1,6-diphosphate in mice.

Fructose-1,6-diphosphate (FDP) exerts a marked activity on reticuloendothelial system (RES) functions, increasing in mice the clearance of colloidal carbon. ATP depletion occurring during phagocytic activity is concentrated by FDP.

Inhibition of Streptococcus mutans adsorption to hydroxyapatite by low-molecular-weight chitosans.

The role of Streptococcus mutans in the initiation of dental caries has been recognized and attributed, at least in part, to its ability to colonize the tooth surface. Therefore, factors which prevent S. mutans attachment to hydroxyapatite (HA) are of considerable interest for the prophylaxis of this infectious disease. Chitosan, a chitin derivative by N-deacetylation, is an interesting candidate in this respect, since it stimulates the ordered regeneration of oral soft tissues, prevents the deleterious action of organic acid, and exhibits bactericidal action against several pathogens. In the present work, the efficacy of a low-molecular-weight chitosan (LMWC) and its derivatives N-carboxymethyl chitosan (NCMC) and imidazolyl chitosan (IMIC) in preventing S. mutans attachment to HA beads was assessed. The effects of chitosan on both sucrose-dependent and -independent adherence were evaluated. In both cases, when saliva-coated or uncoated HA beads were treated with any of the chitosans, a reduction in S. mutans adsorption ranging from 47 to 66% was observed. When HA beads were coated with saliva after the treatment with chitosan, neither carbohydrate caused a statistically significant reduction in S. mutans adsorption, suggesting that saliva deposition restores HA binding properties. Bacteria grown in the presence of chitosan subminimal inhibitory concentrations (sub-MICs) ranging from 12 to 500 micrograms mL-1 adsorbed poorly to HA and exhibited a lower affinity toward xylene than untreated controls. In the presence of chitosan sub-MICs up to 60 micrograms mL-1, an increase in the percentage of detached bacteria from two- to nine-fold was observed. The desorptive effect of chitosan was weaker when S. mutans had adhered to saliva-coated HA in the presence of sucrose. These results demonstrate that the presence of minor amounts of modified chitosans prevents S. mutans adsorption to HA and suggest that colonization of the tooth surface might be impaired by the use of toothpastes, mouthrinses, or chewing gums containing any of the tested polysaccharides.

Macrophage lysozyme stimulation by fructose-1-6-diphosphate.

FDP produces an increase of serum lysozyme concentration which may be related to stimulation of the phagocytic activity. Mice macrophages in vitro produce extracellular and intracellular LSZ (lysozyme) and FDP (fructose-1-6-diphosphate) increases this production. Also in vivo FDP stimulates the macrophages intracellular lysozyme production. The toxic activity in vitro and the protection in vivo against Staphylococcus pyogenes after FDP administration can also be related to macrophage stimulation.

Antiadhesive effect of green and roasted coffee on Streptococcus mutans' adhesive properties on saliva-coated hydroxyapatite beads.

Green and roasted coffees of the two most used species, Coffea arabica and Coffea robusta, several commercial coffee samples, and known coffee components were analyzed for their ability to interfere with Streptococcus mutans' sucrose-independent adsorption to saliva-coated hydroxyapatite (HA) beads. All coffee solutions showed high antiadhesive properties. The inhibition of S. mutans' adsorption to HA beads was observed both when coffee was present in the adsorption mixture and when it was used to pretreat the beads, suggesting that coffee active molecules may adsorb to a host surface, preventing the tooth receptor from interacting with any bacterial adhesions. Among the known tested coffee components, trigonelline and nicotinic and chlorogenic acids have been shown to be very active. Dialysis separation of roasted coffee components also showed that a coffee component fraction with 1000 Da < MW < 3500 Da, commonly considered as low MW coffee melanoidins, may sensibly contribute to the roasted coffee's antiadhesive properties. The obtained results showed that all coffee solutions have antiadhesive properties, which are due to both naturally occurring and roasting-induced molecules.

Human intravenous and intramuscular pharmacokinetics of amoxicillin.

Amoxicillin was administered at doses of 500 mg and 1000 mg, intravenously and intramuscularly to normal volunteers in a parallel study. Intramuscular amoxicillin was 100% bioavailable at both dose levels. Mean peak serum levels observed for the 500 mg and 1000 mg doses, respectively, were: i.v. (5 min after dosing) 46 and 74 micrograms/ml; i.m. (30 min after dosing) 14 and 21 micrograms/ml. Six hour trough levels ranged between 0.5 and 0.9 micrograms/ml. Between 50% and 60% of the doses were excreted in urine as intact amoxicillin in the 24 h after dosing. Almost 90% of this excretion occurred in the first 3 h after dosing. There was a statistically significant increase in mean clearance, after i.v. dosing, from the 500 mg level (14.8 l/h) to the 1000 mg level (20.7 l/h) implying that amoxicillin pharmacokinetics are non-linear over this range. Since there was very little difference between mean renal clearances at these dose levels (9.2 and 11.7 l/h, respectively) this clearance change might be due to enhancement of non-renal clearance. It would not be expected that this non-linearity would have any therapeutic influence.

[Erythromycin: serum and urine levels following rectal administration (author's transl)]. / Studio dei livelli sierici ed urinari dell'eritromicina somministrata per via rettale

The serum and urine levels obtained form administration of Erythromycin are generally good and the antibiotic is absorbed in a similar way; this happens also for the other ways of administration. We have noticed a variability in the absorption of antibiotic as the different components present in the suppositories administered.

Role of surface proteins in Vibrio cholerae attachment to chitin.

The role of surface proteins in Vibrio cholerae attachment to chitin particles in vitro was studied. Treatment of V. cholerae O1 ATCC 14034 and ATCC 14035 with pronase E reduced the attachment of bacteria to chitin particles by 57 to 77%. A statistically significant reduction was also observed when the attachment to chitin was evaluated in the presence of homologous Sarkosyl-insoluble membrane proteins (MPs) (67 to 84%), N-acetylglucosamine (GlcNAc) (62%), the sugar that makes up chitin, and wheat germ agglutinin (40 to 56%), a lectin that binds GlcNAc. The soluble oligomers N,N'-diacetylchitobiose or N,N', N"-triacetylchitotriose caused an inhibition of 14 to 23%. Sarkosyl-insoluble MPs able to bind chitin particles were isolated and visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; two of these peptides (molecular sizes, 36 and 53 kDa) specifically bind GlcNAc.

Surface interactions between Escherichia coli and hemocytes of the Mediterranean mussel Mytilus galloprovincialis lam. leading to efficient bacterial clearance.

The role of type 1 fimbriae in the interactions between Escherichia coli and Mytilus galloprovincialis Lam. hemocytes was evaluated. The association of fimbriated strain MG155 with hemocyte monolayers at 18 degrees C was 1.5- and 3- to 4-fold greater than the association of unfimbriated mutant AAEC072 in artificial seawater and in hemolymph serum, respectively. Such differences were apparently due to different adhesive properties since MG155 adhered more efficiently than AAEC072 when hemocytes were incubated at 4 degrees C to inhibit the internalization process. Hemolymph serum increased both association and adherence of MG155 two- to threefold but did not affect association and adherence of AAEC072. MG155 was also 1.5- to 1.7-fold more sensitive to killing by hemocytes than AAEC072, as evaluated by the number of culturable bacteria after 60 and 120 min of incubation. The role of type 1 fimbriae in MG155 interactions with hemocytes was confirmed by the inhibitory effect of D-mannose. In in vivo experiments MG155 cells were cleared from circulating hemolymph more rapidly than AAEC072 cells were cleared. These results confirm that surface properties are crucial in influencing bacterial persistence and survival within mussel hemolymph.

Effect of low-molecular-weight chitosans on the adhesive properties of oral streptococci.

It was previously shown that a low-molecular-weight chitosan and its derivatives N-carboxymethyl chitosan and imidazolyl chitosan inhibit Streptococcus mutans adsorption to hydroxyapatite. The ability of the same molecules to interfere with adhesive properties of other oral streptococci (Streptococcus sanguis, Streptococcus gordonii, Streptococcus constellatus, Streptococcus anginosus, Streptococcus intermedius, Streptococcus oralis, Streptococcus salivarius, Streptococcus vestibularis) was tested. When saliva-coated or -uncoated hydroxyapatite beads were treated with N-carboxymethyl chitosan, a reduction varying from 60% to 98% depending on strains was observed. Low-molecular-weight chitosans and imidazolyl chitosan did not have any effect. Growth in N-carboxymethyl chitosan-supplemented medium (final concentrations ranging from 20 to 500 micrograms.ml-1) caused a dose related reduction in the adsorption of all strains to hydroxyapatite and in their affinity towards xylene. No effect was observed with low-molecular-weight chitosans and imidazolyl chitosan. In contrast to what observed with S. mutans, the three polysaccharides did not affect detachment from hydroxyapatite beads and adherence to cheek epithelial cells of the other streptococci. These results suggest that low-molecular-weight chitosans and/or imidazolyl chitosan, selectively affecting S. mutans adsorption to hydroxyapatite, may be very interesting as potential anti-dental caries agents.

Fungistatic activity of modified chitosans against Saprolegnia parasitica.

Five chemically modified chitosans were tested for their antifungal activities against Saprolegnia parasitica by the radial growth assay in chitosan-bearing agar, and the fungal growth assay in chitosan-bearing broth. Results indicated that methylpyrrolidinone chitosan, N-carboxymethyl chitosan and N-phosphonomethyl chitosan exerted effective fungistatic action against S. parasitica: in fact the radial growth was nil for 50 h at 20 degrees C, and the fungus was precipitated when the Bacto YM broth contained one of these chitosans. Electron microscopy observations (TEM and SEM) provided evidence of ultrastructural alterations, damaged fungal structures, uptake of modified chitosans, and hyphal distortion and retraction.

Antimicrobial properties of N-carboxybutyl chitosan.

N-Carboxybutyl chitosan, a modified chitin of crustacean origin, displayed inhibitory, bactericidal, and candidacidal activities when tested against 298 cultures of various pathogens. Examination by electron microscopy showed that microbial cells exposed to N-carboxybutyl chitosan underwent marked morphological alterations. The data are of importance in defining the suitability of N-carboxybutyl chitosan as a wound dressing.