Generation and amplification of ultrashort optical pulses

During the last two years since the 1966 Iternational Quantum Electronics Conference further progress toward obtaining high-power light pulses has taken place. An effective method of ultrashort light pulse generation (mode locking) has been developed, further development of the method of coherent amplification of light pulses has been recorded, and new prospective ideas have been put forward. The present paper briefly reports on the data obtained by us in these directions.     

Electron-stimulated reduction of the surface of graphite oxide

Auger-electron spectroscopy has been used to study in situ the initial stage of graphite oxide (GO) reduction under the action of a low-intensity electron beam that does not lead to heating of the irradiated region. It was found that this stage evolves at a rate that is tens of times the rate of the subsequent reduction. It was shown that the fast stage is associated with the removal of oxygen groups from the GO surface. The effective cross sections of the initial and subsequent stages of GO reduction by 1500 eV electrons were found to be σ_in ~ 0.5 × 10^–16 cm² and σ_av ~ 1.2 × 10^–18 cm², respectively.     

Study of sialated neoglycoconjugates by surface enhanced Raman scattering spectroscopy

Neoglycoconjugates based on polyacrylamide and sialic acid with N-acetylneuraminic acid or sialooligosaccharides as side chains were studied by surface-enhanced Raman scattering (SERS) spectroscopy. It had previously been found that these polymers can effectively inhibit influenza virus adhesion. This study revealed the possibility to evaluate, based on the intensity of SERS signals, the overall availability for interaction and the conformational freedom of sialic acid residues in glycoconjugates. The dependence of these two factors on the structure and density of sialylated side chains was studied. The uniformity of distribution of sialylated side chains in conjugates was shown. Comparison of the results of the SERS spectroscopic study of the conjugates and the data on their inhibitory effect on the adhesion of specific strains of influenza virus allowed the identification of the conjugates for which the availability and conformational freedom of sialic acid are the main factors determining their inhibitory properties. A conclusion was also reached about the predominance of one of the mechanisms (competitive inhibition or steric stabilization) in the inhibitory properties of the specific conjugates.     

Relation between the space flight-induced frequency of dominant lethal mutations and the level of allozyme heterozygosity in Drosophila melanogaster populations

Currently, the treatment of falciparum malaria is seriously compromised by spreading drug resistance. We studied the effects of camptothecin, a potent and specific topoisomerase I inhibitor, on erythrocytic malaria parasites in vitro. In Plasmodium falciparum, camptothecin trapped protein-DNA complexes, inhibited nucleic acid biosynthesis, and was cytotoxic. These results provide proof for the concept that topoisomerase I is a vulnerable target for new antimalarial drug development.     

The dynamic follow-up of the status of patients with acute pancreatitis using a degree-of-severity scale

The authors have developed a method of dynamic control over the patients with acute pancreatitis using the lineal coefficient of gravity rating, which is based on objective parameters. This dynamic control was applied in 300 patients and made it possible to choose the most effective methods of treatment.     

Surface enhanced Raman spectroscopy for characterization of structural characteristics of carbon chains in alpha1-acid glycoprotein and pseudoglycoproteins]

Surface-enhanced Raman scattering (SERS) spectroscopy was used to study the structure of carbohydrate chains in glycosylated forms of alpha 1-acid glycoprotein (AGP) and in pseudoglycoproteins obtained by transferring the carbohydrate chains of AGP to a polyacrylamide carrier. It was found that AGP-D glycoform and pseudoglycoproteins containing three or more glycans per molecule, which possess high immunomodulating activity, have a specific spatial organization of carbohydrate chains. This organization is maintained by the interaction of neighboring glycans with each other and does not depend on the nature of the carrier (whether it is polypeptide or polyacrylamide).     

A comparison of the hypolipidemic action of probucol at doses of 500 and 1000 mg/day in moderate hyperlipoproteinemia

AIM: Evaluation of effectiveness of hypolipidemic action of probucol in doses 500 and 1000 mg/day and comparison of probucol blood concentrations on the treatment month 3 and 6. MATERIALS AND METHODS: Probucol (Akrikhin, Russia) was given to 41 patients with primary hypercholesterolemia in a dose 500 mg/day. 3 months later the patients were divided into two groups. Group 1 patients exhibited a > 10% decrease in cholesterol levels and continued to take probucol in the dose 500 mg/day. Group 2 patients were crossed over to higher cholesterol dose--up to 1000 mg/day. Lipids levels were measured by enzyme tests, apoproteins--by immunoturbidimetry and immunodiffusion, probucol concentrations--by high-performance liquid chromatography. RESULTS: After 3 months of treatment, cholesterol lowered by 14.3 and 9.2% in groups 1 and 2, respectively. After 6 months, by 19.7 and 12.9%, respectively. Probucol concentrations in blood were higher after 6 months of treatment than after 3 months in both groups. No significant differences existed between the groups by probucol concentrations in 3 and 6 months. CONCLUSION: Hypolipidemic effect of probucol depended on the individual features of lipoproteins metabolic disorders rather than the drug blood concentration. Larger probucol doses fail to reduce cholesterol further.