A new spectroscopic technique, rotational-echo double-resonance (REDOR) NMR, for solids utilizes magic-angle spinning and measures directly the dipolar coupling between stable-isotope-labeled nuclei ...and, thus, interatomic distances. REDOR has been used to measure the {sup 13}C-{sup 15}N interatomic distance in a nine-residue fragment, Ac-Phe-MeA(1-{sup 13}C)-MeA(d{sub 6})-MeA-Val-Gly({sup 15}N)-Leu-MeA-MeA-OBzl (MeA = {alpha}-methylalanine or aminoisobutyric acid (Aib)), of the peptide antibiotic emerimicin. The crystal structure of the peptide emerimicin 1-9 benzyl ester was determined previously, and the measurement by REDOR of a known interatomic distance allows both validation and a practical demonstration of the precision of REDOR. The ability to map precisely intermolecular distances suggests applications of REDOR in the solid, or aggregated state, for determinations of the conformations of ligand molecules in drug-receptor, inhibitor-enzyme, and antigen-antibody complexes.
In order to test the influence of chemical modifications designed to allow covalent coupling of channel-forming peptide motifs into variable sized oligomers, a series of alamethicin derivatives was ...prepared. The building block encompassing the N-terminal 1–17 residues of alamethicin behaved normally in the conductance assay on planar lipid bilayers, albeit at higher concentration and with a slightly reduced voltage-dependence. A linker Ac-K-OCH
2C
6H
4CH
3
p attached via the epsilon amino group of lysine to the C-terminus of alamethicin(1–17) increased membrane affinity. The latter was further enhanced in a dimer and a tetramer in which alamethicin(1–17) chains were tethered to di- or tetra-lysine linkers, respectively, but macroscopic current–voltage curves displayed much reduced voltage-dependencies and reversed hysteresis. An usual behaviour with high voltage-dependence was restored with the modified dimer of alamethicin(1–17) in which alanine separated the two consecutive lysine residues in the linker. Of special interest was the development of a ‘negative resistance’ branch in macroscopic current–voltage curves for low concentrations of this dimer with the more flexible linker. Single channel events displayed only one single open state with fast kinetics and whose conductance matches that of the alamethicin heptamer or octamer.
Linear and cyclic hymenistatin I (HS I) analogues with dipeptide segments Ile2-Pro3 Pro3-Pro4 and Val6-Pro7 replaced by their tetrazole analogues Ile2-psiCN4-Ala3', Pro3-psiCN4-Ala4 and ...Val6-psiCN4-Ala7 were synthesized by the solid phase peptide synthesis method and cyclized with the TBTU and/or HATU reagent. The peptides were examined for their immunosuppressive activity in the lymphocyte proliferation test (LPT).
Residues of Triton X‐100 C8H17‐C6H4‐(O‐CH2‐CH2)9‐10‐O‐ were bound by ether bonds to inulin, dextran, amylose, and cellulose‐yielding compounds containing 10–30, 5, 19 and 6% (w/w) of Triton X‐100 ...residue respectively. The water‐soluble inulin derivative was studied in detail. This compound was fractionated on the basis of molecular weight by gel chromatography and on the basis of degree of substitution by adsorption to polystyrene resin. Even the residues of Triton X‐100 which were bound to a single inulin macromolecule were able to form a micelle; in addition to these monomolecular micelles the inulin derivative was able to form polymolecular micelles as well. The inulin derivative was effective in solubilizing proteins and phospholipids from membranes of human erythrocytes and liberated reverse transcriptase activity from the membrane‐enveloped virions of murine leukemia. The Triton X‐100 inulin derivative abolished binding of the 3H‐labelled antagonist dihydroalprenolol to solubilized preparations of β‐adrenergic receptors from frog erythrocytes in a dose‐related manner similar to the inactivation produced by Triton X‐100, while digitonin, a detergent containing a bulkier hydrophobic group, did not cause inactivation. On the basis of its Triton X‐100 content, the inulin derivative was found to be less detrimental to the growth of murine erythroleukemic cells in vitro than Triton X‐100 alone when short (2–4 h) exposures were used, but this difference disappeared at longer (1–3 day) exposures. Results thus suggest that the increase in size of the hydrophilic part of the detergent brings about moderation in those effects of the detergent which are dependent on the rate of diffusion, while the solubilizing and inactivating effects of the detergent were not changed. It is probably the size of the hydrophobic part which is important in protein‐inactivating properties of the detergent.
Pregnancy in women who are organ recipients has long been a controversial issue due to the lack of data on the safety of immunosuppressive drugs for the developing foetus. Scientific data show that ...the effect of immunosuppressants on the foetus causes an impairment of T and B lymphocyte function and a reduction in their total number. For this reason, some authors recommend delaying the obligatory immunization of infants. The aim of the study is to analyse the impact of chronic immunosuppressive therapy used during pregnancy by women after organ transplantation on the effectiveness of anti-viral vaccinations in the children of these women.
Concentrations of post-vaccination IgG antibodies (measles, HBV, polio) in 18 children of post-transplant mothers (9KTRs; 9LTRs) were determined using the ELISA method. The results were compared with the control group (
= 21). The incidence of vaccination AEs was also analysed.
There were no significant differences between the analysed groups in the concentrations of antibodies against HBV, measles and polio (
> 0.05).
No difference was observed in the immunogenicity of HBV, polio and measles vaccinations between children of post-transplant mothers and the general population. The immunization of children of post-transplant mothers is safe, and the percentage of adverse post-vaccination events does not differ from the general population. The obtained study results do not indicate the necessity for modifying the vaccination program for HBV, measles, and polio in this group of patients.
Human colostrum (HC) is a rich source of immune mediators that play a role in immune defences of a newly born infant. The mediators include transforming growth factor β (TGF-β) which exists in three ...isoforms that regulate cellular homeostasis and inflammation, can induce or suppress immune responses, limit T helper 1 cells (Th1) reactions and stimulate secretory immunoglobulin A (IgA) production. Human milk TGF-β also decreases apoptosis of intestinal cells and suppresses macrophage cytokine expression. The aim of the study was to determine the concentration of TGF-β2 in HC obtained from the mothers who delivered vaginally (VD) or by caesarean section (CS), and to compare the concentrations in HC from mothers who delivered at term (TB) or preterm (PB). In this study, 56% of preterm pregnancies were delivered via CS. The concentrations of TGF-β2 were measured in HC from 299 women who delivered in the 1st Department of Obstetrics and Gynaecology, Medical University of Warsaw: 192 (VD), 107 (CS), 251 (TB), and 48 (PB). The colostrum samples were collected within 5 days post-partum. TGF-β2 levels in HC were measured by the enzyme-linked immunosorbent assay (ELISA) test with the Quantikine ELISA Kit-Human TGF-β2 (cat.no. SB250). Statistical significance between groups was calculated by the Student
-test using StatSoft Statistica 13 software. The mean TGF-β2 concentration in patients who delivered at term or preterm were comparable. The levels of TGF-β2 in HC were higher after preterm than term being 4648 vs. 3899 ng/mL (
= 0.1244). The delivery via CS was associated with higher HC concentrations of TGF-β2. The levels of TGF-β2 were significantly higher in HC after CS than VD (7429 vs. 5240 ng/mL;
= 0.0017). The data from this study suggest: caesarean section was associated with increased levels of TGF-β2 in HC. The increased levels of TGF-β2 in HC of women who delivered prematurely require further research. Early and exclusive breast-feeding by mothers after caesarean section and premature births with colostrum containing high TGF-β2 levels may prevent the negative impact of pathogens which often colonize the gastrointestinal tract and may reduce the risk of chronic diseases in this group of patients.
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