Cyano-tryptophans as dual infrared and fluorescence spectroscopic labels to assess structural dynamics in proteins.

The steady state and time-resolved fluorescence and infrared (IR) properties of 4- and 5-cyanotryptophan (CNTrp) are investigated and compared, and the tryptophan (Trp) analogs are found to be very attractive to study structural and dynamic properties of proteins. The position of the nitrile substitution as well as the solvent environment influences the spectroscopic properties (solvatochromism). Similar to native Trp, electronic (nanosecond) lifetime and emission spectra are modulated by the environment, making CNTrps attractive fluorescent probes to study the structural dynamics of proteins in complex media. The nitrile absorption in the IR region can provide local structural information as it responds sensitively to changes in electrostatics and hydrogen bond (HB) interactions. Importantly, we find that 4CNTrp exhibits a single absorption in the nitrile stretch region, while the model compound 4CN-indole (4CNI) shows two. Even though the spectrum of the model compound is perturbed by a Fermi resonance, we find that 4CNTrp itself is a useful IR label. Moreover, if the nitrile group is substituted at the 5 position, the Trp analog predominantly reports on its HB status. Because the current literature on similar compounds is too limited for a detailed solvatochromic analysis, we extend the available data significantly. Only now are microscopic details such as the mentioned sensitivity to electrostatics coming to light. The vibrational lifetime of the CN moiety (acting on a picosecond time scale in contrast to the nanosecond time scale for fluorescent emission) allows for its application in 2D-IR spectroscopy in the low picosecond range. Taken together, the benefits of CNTrps are that they absorb and emit separately from the naturally occurring Trp and that in these dual fluorescence/vibrational labels, observables of IR and fluorescence spectroscopy are modulated differently by their surroundings. Because IR absorption and fluorescence operate on different time and length scales, they thus provide complementary structural information.

Inhibitory effects of sulfonated shale oil fractions on the oxidative burst and Ca++ mobilization in stimulated macrophages.

The effect of sulfonated shale oil fractions on the oxidative burst and the mobilization of intracellular calcium in purified guinea pig peritoneal macrophages was investigated in vitro. Three sulfonated shale oil fractions of varying boiling range, No. 1 = R = 1269 (powder, sodium salt of sulfonated shale oil dark), No. 2 = R 3269 (watery solution, sodium salt of sulfonated shale oil pale, Ichthyol hell), No. 3 = R 2069 (watery solution, ammonium salt of sulfonated shale oil dark, Ichthyol) were investigated. Two of three compounds dose-dependently inhibited leukotriene (LT) B4-induced Ca++ mobilization with complete inhibition at 10 mumol/l. The phorbol ester-stimulated generation of superoxide anion was dose-dependently inhibited by all three compounds with an optimal concentration of 1 to 10 mumol/l and maximal inhibition of 34.7, 39 and 38%. High concentrations of the compounds promoted the release of superoxide anion into the buffer medium. The LTB4-stimulated generation of hydrogen peroxide was also dose-dependently inhibited by all three compounds with maximal inhibition of 34, 40 and 32% with an optimal concentration of 100 mumol/l. Our observations support the hypothesis that sulfonated shale oil fractions are capable of modulating inflammatory responses through inhibition of inflammatory cell functions.

Reduced urinary serotonin excretion after intake of high doses of hypoxanthine.

Two healthy volunteers were treated with hypoxanthine 3 x 1 g and allopurinol 3 x 100 mg daily for 1 week. During this treatment serum oxypurine concentration and urinary oxypurine excretion increased as expected. No side effects were observed except for some mild daytime drowsiness and lethargy. Measurements of urinary serotonin (5-HT) excretion showed decreases to as much as 60% below initial values. Decreased urinary 5-HT excretion was also found in a patient with incomplete Lesch-Nyhan syndrome during treatment with high doses of hypoxanthine. His neurological symptoms improved slightly. The results suggest that high doses of hypoxanthine exert a nonspecific sedative effect on both patients with Lesch-Nyhan syndrome and healthy controls. The cause is probably a reduced synthesis or release of 5-HT.

Cholesterol fractions and triglycerides in children and adults with Down's syndrome.

In 186 patients with Down's syndrome (age 1-68 yr) total cholesterol and triglycerides were determined, quantitative lipoprotein electrophoresis was performed and cholesterol fractions and beta/alpha-lipoprotein ratios were calculated. A reference group of 51 non-mongoloid mentally handicapped adults living in the same institutions were examined in the same way. Patients' total cholesterol, beta-cholesterol and triglycerides did not differ from the controls. However, alpha-cholesterol was significantly lower and the beta/alpha-lipoprotein ratio significantly higher in patients, findings which are associated in the general population with a high risk for premature atherosclerosis. Interestingly, mortality causes and pathological findings in Down's syndrome show no increased frequency of cardiovascular diseases.

A new method for the determination of serum iron: potentiostatic coulometry with the Ferrochem 3050.

Potentiostatic coulometry allows the fast determination of iron in serum samples of 50 microliters serum or less. Precision, accuracy, specificity and practicability of the method were evaluated using the Ferrochem 3050, and found to be favourable. This method can therefore be recommended to all laboratories in which small sample volumes have to be analysed.