Synthesis and acid ionization constants of cyclic cystine peptides

Cyclic peptide disulfides of the general formula were synthesized from the corresponding peptide derivatives [Boc-Cys(Trt)(Gly)-_n-Cys(Trt)-OBu^t] by oxidation with iodine in methanol and by subsequent removal of the terminal groups with trifluoroacetic acid. Acid ionization constants of the obtained peptides were determined by potentiometric titration in aqueous KCl (0.1 mol/L) medium. All compounds have two dissociable hydrogens, corresponding to carboxyl (pK¹= 2.35–2.84) and to terminal amino group (pK₂= 5.61–6.93); pK₁, values show first an upward and then a downward trend with the increase in ring size; the opposite is true for pK₂, values. These trends could be tentatively attributed to the intramolecular salt bridge (-COO——-NH⁺₃-) formation.     

Mechanism of action of baclofen on myocardial and vascular contractility

Department of Anatomy and Physiology of Man and Animals, A. I. Gertsen Leningrad Pedagogic Institute. Department of Pharmacology, Academician I. P. Pavlov First Leningrad Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. V. Val'dman.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 106, No. 10, pp. 436–438, October, 1988.     

Genetic markers in the Tuvan population of Todja, Siberia

Todja is a secluded region of northern Tuva situated in the Sayany Mountains, Siberia. The aboriginal population of Todja is Tuvan. A total of 128 healthy Tuvans living in Todja were typed for HLA-A, -B and -C antigens and several plasma and erythrocyte protein polymorphisms (Hp, Tf, Gc, ESD, ACP, PGM1, PGD and ADA). The observed frequencies of all 8 blood protein and HLA genotypes were in agreement with Hardy-Weinberg expectations. The most frequent HLA antigens in Todjans are A2 (0.36). A3 (0,24), A9 (0.50), B15 (0.34) and B40 (0.50). HLA haplotypes A2B5, A2B40, A9B15 and A9B40 are most common in this population. The observed frequencies of protein polymorphisms and HLA antigens and haplotypes in Todjans are similar to those of other Mongoloid populations. A comparison of HLA frequencies currently observed in Todjans with those obtained 20 years ago at the same locality showed minor changes attributable to the effect of migration.     

Receptor-binding properties of modern human influenza viruses primarily isolated in Vero and MDCK cells and chicken embryonated eggs

To study the receptor specificity of modern human influenza H1N1 and H3N2 viruses, the analogs of natural receptors, namely sialyloligosaccharides conjugated with high molecular weight (about 1500 kDa) polyacrylamide as biotinylated and label-free probes, have been used. Viruses isolated from clinical specimens were grown in African green monkey kidney (Vero) or Madin-Darby canine kidney (MDCK) cells and chicken embryonated eggs. All Vero-derived viruses had hemagglutinin (HA) sequences indistinguishable from original viruses present in clinical samples, but HAs of three of seven tested MDCK-derived isolates had one or two amino acid substitutions. Despite these host-dependent mutations and differences in the structure of HA molecules of individual strains, all studied Vero- and MDCK-isolated viruses bound to Neu5Ac alpha2-6Galbeta1-4GlcNAc (6'SLN) essentially stronger than to Neu5Acalpha2-6Galbeta1-4Glc (6'SL). Such receptor-binding specificity has been typical for earlier isolated H1N1 human influenza viruses, but there is a new property of H3N2 viruses that has been circulating in the human population during recent years. Propagation of human viruses in chicken embryonated eggs resulted in a selection of variants with amino acid substitutions near the HA receptor-binding site, namely Gln226Arg or Asp225Gly for H1N1 viruses and Leu194Ile and Arg220Ser for H3N2 viruses. These HA mutations disturb the observed strict 6'SLN specificity of recent human influenza viruses.     

Preliminary results of medical research on board the "Mir" orbital complex during its second main mission

In 1987 the USSR orbital complex "Mir" accomplished its space mission, crewed by Yu.V. Romanenko (326 days), and A.I. Laveykin (about 176 days), who was replaced on the orbit (in consequence of some cardiac function peculiarities revealed in exercise conditions) by A.P. Aleksandrov (about 160 days). During the flight, extravehicular activity in the open space was carried out three times, and conjoint programmes were conducted, over a period of seven days, with an international Soviet-Syrian crew. The most important, fundamental result of the medical studies carried out in this flight seems to be the noted fact that Yu.V. Romanenko's 326 days in-flight (which means 3 months in excess to the results obtained hitherto) and his activity was not accompanied by developing any quantitatively new functional shifts, when compared to other long-term flights. Besides that, the cosmonaut maintained his functional endurance and work capacity on satisfactory levels. These results are in apparent relation with the rationally composed crew complement, the contribution the ground services responsible for the work-rest regimen and the whole life activity on board the station, as well as with the systematic and sufficiently extensive use of preventive measures. The general feeling and work capacity of the other crew members were also good throughout the flight. However, the reactions observed in each cosmonaut showed their individual characteristics, which are discussed in the paper.     

Counseling Fathers (2010) by C.Z. Oren and D.C. Oren

No abstract available for this article.