[Autoantibodies to M2-cholinoreceptors as a potential development factor of arrhythmia in patients with paroxysmal atrial fibrillation].

AIM: We aimed to assess autoantibodies to M2-cholinoceptors (M2-CR) in patients with paroxysmal lone atrial fibrillation (AF) and in patients with AF and arterial hypertension (AH). MATERIALS AND METHODS: 100 patients with lone AF and 84 patients with AF and AH were included. Patients underwent clinical blood and urinalysis, assessment of biochemistry blood panel, 12-lead ECG, 24-hour Holter monitoring, echocardiography and stress - testing (treadmill or stress - echocardiography). Assessment of IgM and IgG autoantibodies to M2-CR was performed by indirect immunoenzyme assay. The following peptide molecules were used as epitopes for detection of autoantibodies: M1 - amino acid sequence YTVIGYWPLGVVCDL (83-98) of the first extracellular loop of M2-CR; M2 - sequence VRTVEDGECYIQFFSNAAVTFGTAI (168-192) of the second extracellular loop of M2-CR; M3 - sequence NTFCAPCIPNTV (410-421) of the third extracellular loop of M2-CR; M4 - short sequence VEDGECYIQFFS (171-182) of the second extracellular loop of M2-CR; M1+M4 - chimeric molecule formed by sequences of the first and the second extracellular loops of M2-CR connected by disulfide bound YTVIGYWPLGVVCDL + VEDGECYIQFFS (83-98 + 171-182). RESULTS: Autoantibodies to M2-CR were found in 45% patients with lone AF and in 35% patients with AF and AH. In patients with lone AF prevalence of increased IgG to M2-CR were greater than in patients with AF and AH (32% vs 20%; p.

[Tyramine and tryptamine as ligands for medical and biotechnological affinity sorbents].

A novel technique for preparation affinity sorbent based on tyramine and tryptamine was proposed. It was shown that tryptamine-Sepharose and tyramine-Sepharose effectively bind IgG, IgA, lipoprotein (a) (Lp(a)) and low density lipoproteins (LDL) from blood plasma. The sorption capacity is 4-9 mg of IgG, 2-4 mg IgA, 3-5:mg of Lp(a) and 5-7 mg of LDL per mL of gel. It was found that new sorbents can bind Lp(a) and IgG as themselves or in a complex of Lp(a) with IgG. The existence of this complex may indicate the presence of anti-Lp(a) autoantibodies in the blood of some patients. The advantages of new sorbents are easiness of its synthesis and stability during use and storage. In practice they can be applied for medical and biotechnological purposes where it is necessary to bind Lp(a), LDL, IgG, IgA.

[Affine Haemosorbents Based on Aromatic Peptides for Binding of the Immunoglobulin G].

Affinity haemoadsorbents based on WY, WTY, WNY ligands and polysaccharide matrix were developed for the human immunoglobulin G binding. The characteristics of new sorbents such as the binding of total IgG and binding of IgG subclasses were compared. It was found that all new sorbents well extract the IgG from the blood plasma. It was evidenced that WNY-based sorbent is more effective for binding of IgG subclass 3. The determination of physic-chemical characteristics of IgG binding revealed that desorption constants for IgG are 10 ± 3, 28 ± 4 and 13 ± 3 µM for WY, WTY, WNY based sorbents respectively. Maximum sorption capacities for IgG are 43 ± 2, 45 ± 3 and 46 ± 3 mg IgG per ml of sorbent for WY, WTY, WNY based sorbents respectively. Also it was shown that the new sorbents are compatible with blood and are suitable for the medical purposes.

Identification of 130 kDa cell surface LDL-binding protein from smooth muscle cells as a partially processed T-cadherin precursor.

Atypical cell surface lipoprotein-binding proteins of 105 kDa and 130 kDa are present in membranes of vascular smooth muscle cells. We recently identified the 105 kDa protein from human aortic media as T-cadherin, an unusual glycosylphosphatidylinositol (GPI)-anchored member of the cadherin family of cell adhesion proteins. The goal of the present study was to determine the identity of 130 kDa lipoprotein-binding protein of smooth muscle cells. We applied different approaches that included protein sequencing of purified protein from human aortic media, the use of human T-cadherin peptide-specific antisera, and enzymatic treatment of cultured cells with trypsin and GPI-specific phospholipase C. Our results indicate that the 130 kDa protein is a partially processed form of T-cadherin which is attached to the membrane surface of smooth muscle cells via a GPI anchor and contains uncleaved N-terminal propeptide sequence. Our data disclose that, in contrast to classical cadherins, T-cadherin is expressed on the cell surface in both its precursor (130 kDa) and mature (105 kDa) forms.