Quinine sulfate and bacterial invasion

Background

As many patients who receive antimalarial drugs for treatment of noninfectious, inflammatory diseases are also immunosuppressed and might have a concomitant bacterial infection, we studied the effectiveness of these drugs against bacterial infections, to find out whether they could protect against (and even treat) such conditions and obviate the need for an additional antibiotic drug.

Methods

Effect of QS on bacterial growth: Escherichia coli (E. coli) HB101 pRI203 were cultured overnight at 37°C in TSB and inoculated (approx 1 × 10⁷ cells /ml) in MEM in the presence of QS at various concentrations (0, 50 and 100 μM).The effect of QS at concentration of 50 and 100 μM on the entry process of E. coli HB101 pRI203 into HeLa cells was studied under different experimental conditions: 1. QS was incubated with 3 × 10⁵ HeLa cells for 60 min at 37°C prior to infection. 2. QS was added to HeLa cell monolayers during the infection period.

Results

QS showed no antibacterial activity after 24 h of incubation.The invasive efficiency of the bacteria was significantly inhibited at a dose-dependent manner, when QS was added to HeLa cells for 60 min at 37°C prior to infection (condition 1), and to a lesser extent when added during the period of infection (condition 2).

Conclusions

Although the antimalarials are generally regarded as being inactive against most extracellular bacterial species, our results indicate that QS significantly inhibited the internalization/invasion efficacy of E. coli in the host cells.

     

The abundance of additional N-acetyllactosamine units in N-linked tetraantennary oligosaccharides of human Tamm-Horsfall glycoprotein is a donor-specific feature

Previously, treatment of Tamm-Horsfall glycoprotein (THp) from different donors with endo-beta-galactosidase has been shown to liberate a tetra- and a Sd(a)-active pentasaccharide, concluding the presence of N-linked carbohydrate chains containing additional N - acetyllactosamine units. These type of oligosaccharides were not found in a detailed structure elucidation of the carbohydrate moiety of THp of one male donor, suggesting a donor-specific feature for these type of structures. Therefore, THp was isolated from four healthy male donors and each subjected to endo-beta-galactosidase treatment in order to release these tetra- and Sd(a)-active pentasaccharide. Differences were observed in the total amount of released tetra- and Sda-active pentasaccharide of the used donors (42, 470, 478, 718 microg/100 mg THp), indicating that the presence of repeating N-acetyllactosamine units incorporated into the N-glycan moiety of THp is donor specific. Furthermore, a higher expression of the Sd(a) determinant on antennae which display N-acetyllactosamine elongation was observed, suggesting a better accessibility for the beta-N-acetylgalactosaminyltransferase. In order to characterize the N-glycans containing repeating N- acetyllactosamine units, carbohydrate chains were enzymatically released from THp and isolated. The tetraantennary fraction, which accounts for more than 33% of the total carbohydrate moiety of THp, was used to isolate oligosaccharides containing additional N - acetyllactosamine units. Five N-linked tetraantennary oligosaccharides containing a repeating N-acetyllactosamine unit were identified, varying from structures bearing four Sd(a) determinants to structures containing no Sd(a) determinant (see below). One compound was used in order to specify the branch location of the additional N- acetyllactosamine unit, and it appeared that only the Gal-6' and Gal-8' residues were occupied by a repeating N -acetyllactosamine unit.      

Hydration of N-palmitoylgalactosylsphingosine compared to monosaccharide hydration

Differential scanning calorimetry (DSC) studies of the ice-water transition of N-palmitoylgalactosylsphingosine (NPGS) (cerebroside)/water mixtures indicate 4 +/- 1 non-freezable water molecules per molecule NPGS. This hydration level, representing strongly bound water, is identical to that observed previously for human glucocerebroside (Bach, D., Sela, B. and Miller, I.R. (1982) Chem. Phys. Lipids 31, 381). Comparison of gluco- and galacto-cerebroside hydration with hydration measurements on simple monosaccharides suggests a favored orientation of the glycosyl polar group at the cerebroside-water interface.     

Uptake kinetics of 99Tc in common duckweed

The uptake of the nuclear waste product technetium-99 was studied in common duckweed (Lemna minor). In addition to measurements, a model involving two compartments in duckweed with different chemical forms of technetium was derived. The model was tested by chemical speciation, i.e. differentiating between reduced Tc-compounds and Tc(VII)O(4)(-). The TcO(4)(-) concentrations measured were in good agreement with those predicted by the model. Two processes determine technetium uptake: (1) transport of Tc(VII)O(4)(-) across the cell membrane, and (2) reduction of Tc(VII). The TcO(4)(-) concentration in duckweed reaches a steady state within 2 h while reduced Tc-compounds are stored, as a result of absence of release or re-oxidation processes. Bioaccumulation kinetic properties were derived by varying 99Tc concentration, temperature, nutrient concentrations, and light intensity. The reduction of technetium in duckweed was highly correlated with light intensity and temperature. At 25 degrees C the maximum reduction rate was observed at light intensities above 200 μmol m(-2) s(-1) while half of the maximum transformation rate was reached at 41 μmol m(-2) s(-1). Transport of TcO(4)(-) over the cell membrane requires about 9.4 kJ mol(-1), indicating an active transport mechanism. However, this mechanism behaved as first-order kinetics instead of Michaelis-Menten kinetics between 1x10(-14) and 2.5x10(-5) mol l(-1) TcO(4)(-). Tc uptake could not be inhibited by 10(-3) mol l(-1) nitrate, phosphate, sulphate or chloride.     

Characterization and Distribution of Selenite Reduction Products in Cultures of the Marine Yeast Rhodotorula mucilaginosa-13B

Selenite reduction by fungi is a widespread and ecologically significant phenomenon, but previous studies of fungal isolates have not fully characterized the reduction products. We investigated selenite reduction and the distribution of Se in cultures of the marine yeast Rhodotorula mucilaginosa-13B. Strain 13B reduced a substantial amount of selenite to form amorphous elemental selenium particles. Minor volatilization was also observed. Under the aerobic experimental conditions, intact 13B cultures were required for substantial distribution to the solid and volatile phases. This is the first study to report comprehensive microscopic image data and spectroscopic analyses confirming the accumulation of amorphous Se⁰ particles external and internal to cells of a Rhodotorula strain.     

Frequency of the ΔF508 mutation in a sample of 175 Italian cystic fibrosis patients

Summary A sample of 175 Italian cystic fibrosis patients has been analysed for the presence of the ΔF508 mutation. The frequency of this mutation among 137 patients with pancreatic insufficiency is equal to 57%; in 23 patients with pancreatic sufficiency it is 26%. A high proportion of the unknown mutations is associated with the same rare haplotype found in association with ΔF508, suggesting that at least another mutation occurred on a chromosome characterized by the same haplotype.