[Detection of Autoantibodies Against the 1-Adrenergic Receptor in the Sera of Patients via the Competitive cell-Based Enzyme Linked Immunosorbent Assay].

OBJECTIVE: This study aimed to assess the level of anti-1-adrenergic receptor autoantibodies in patients with ventricular arrhythmias with no signs of organic heart disease and with presence of cardiovascular pathology in comparison with a group of healthy volunteers. MATERIAL AND METHODS: The study included 44 patients with ventricular arrhythmias with no signs of organic heart disease ("idiopathic"), 34 patients with diagnosed dilated cardiomyopathy (DCM) of inflammatory origin, 35 patients with coronary heart disease and ventricular arrhythmias, 12patients with coronary heart disease with no ventricular arrhythmias, and 19 healthy volunteers (control group). The level of autoantibodies against the 1-adrenergic receptor was determined by the developed competitive cell-based enzyme-linked immunosorbent assay (ELISA) and by the standard ELISA using peptides corresponding to the second extracellular loop of the 1-adrenergic receptor. RESULTS: Elevated level of autoantibodies detected by a competitive cell-based ELISA was observed in 62% of patients with DCM compared to 21% of healthy volunteers (p=0.0006). In patients with "idiopathic" ventricular arrhythmias, the level of 1-adrenergic receptor autoantibodies was lower than in healthy subjects (p=0.003). Coronary heart disease patients with or without ventricular arrhythmias exhibited no differences from the control group. The number of significantly positive signals in peptide-based ELISA did not exceed 10% in any of the groups. No correlation between the data from competitive cell-based ELISA and peptide-based ELISA was found. CONCLUSIONS: This study demonstrated that competitive cell-based ELISA technique can be applied for detection of 1-adrenergic receptor autoantibodies. The results in DCM patients generally correspond to the expected. Decreased level of autoantibodies in patients with "idiopathic" ventricular arrhythmias indicates that this disease is related to changes in the immune system. Such relation is not observed in the case of coronary heart disease patients.

[Development and use of a domestic test system for diagnosis of tuberculous infection on the basis of quantitative analysis of interferon-gamma induction in whole blood samples in vitro, by using specific recombinant antigens].

A test system was developed to detect tuberculous infection by qualitative analysis of interferon-gamma (IFN-gamma) in the plasma samples after 20-24-hour incubation of whole blood samples in the presence of Mycobacterium tuberculosis (MBT) antigens: tuberculin PPD and a mixture of the MBT-specific recombinant antigens ESAT-6 and CFP-10. The analysis used 3 test tubes each containing 1 ml of heparinized venous blood, one of which served as a control; the other two test tubes were employed to measure antigen-induced IFN-gamma production. Whether this test system might be used to determine primary tuberculous infection was studied in 277 children and adolescents. The threshold diagnostic IFN-gamma induction level determined in the test tube containing a mixture of the antigens ESAT-6 and CFP-10 was ascertained. Postvaccine allergy was detectable if there was IFN-gamma induction in the test tube containing tuberculin and if there was no diagnostic IFN-gamma level in that containing the antigens ESAT-6 and CFP-10. The diagnostic sensitivity of detection of primary tuberculous infection was 97.6% with 94.4% specificity, which enabled this condition to be differentiated from postvaccine allergy. The level of antigen-induced IFN-gamma may be lower in relatively disseminated forms of pulmonary tuberculosis.

[The effect of 15-ketosterol analogues with a 5,6-dimethylhept-3-en-2-yl chain at C17 on cholesterol metabolism in Hep G2 hepatoma cells]. / Vliianie analogov 15-ketosterina, soderzhashchikh 5,6-dimetilgept-3-en-2-il'nuiu tsep' pri C17, na metabolizm kholesterina v kletkakh gepatomy HepG2.

The effect on cholesterol metabolism in Hep G2 hepatoma cells was studied for new analogues of 15-ketosterol [3beta-hydroxy-5alpha-cholest-8(14)-en-15-one] (I): (24S)-3beta-hydroxy-24-methyl-5alpha-cholesta-8(14),22-diene-15-one (II), (24S)-3alpha-hydroxy-24-methyl-5-alpha-cholesta-8(14),22-diene-15-one (III), and (24S)-24-methyl-5alpha-cholesta-8(14),22-diene-3,15-dione (IV). Analogues (I) and (II) were found to be equally effective inhibitors of cholesterol biosynthesis after a 3-h incubation with Hep G2 cells; however, (II) produced a stronger inhibitory effect after a 24-h incubation or after an incubation of cells preliminarily treated with the inhibitor in a medium containing no ketosterol. The ability of ketosterols to inhibit cholesterol biosynthesis decreased in the order (II) > (IV) > (III). Ketosterol (II) inhibited, whereas ketosterol (III) stimulated the biosynthesis of cholesteryl esters. (IV) stimulated the biosynthesis of cholesteryl esters at a concentration of 1-10 microM and exerted no marked effect at a concentration of 30 microM. These results indicate that delta8(14)-15-ketosterols containing a modified side chain are of interest as regulators of cholesterol metabolism in liver cells. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 5; see also http: // www.maik.ru.

[Interaction of acyl derivatives of 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one and 3alpha-hydroxy-5alpha-cholest-8(14)-en-15-one with hepatoma hep G2 cells]. / Vzaimodeistvie atsil'nykh proizvodnykh 3beta-gidroksi-5alpha-kholest-8(14)-en-15-ona i 3alpha-gidroksi-5-alpha-kholest-8(14)-en-15-ona s kletkami gepatomy Hep G2.

Effects of 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one (I), 3alpha-hydroxy-5alpha-cholest-8(14)-en-15 one (II), 3beta-hexadecanoyloxy-5alpha-cholest-8(14)-en-15-one (III), 3alpha-hehadeeanoyloxy-5alpha-cholest-8(14)-en-15-one (IV), 3beta-acetoxy-5alpha-cholest-8(14)-en-15-one (V), 3alpha-acetoxy-5alpha-cholest-8(14)-en-15-one (VI) on cholesterol metabolism in hepatoma Hep G2 cells were studied. Compound III slowly bind to Hep G2 cells followed by internalization and metabolic transformation (at a concentration of 30 microM the total binding of compound III was (3.9 +/- 0.4) nmol per 1 mg of cell protein for 24 h incubation). Compound I depressed and compound III stimulated the uptake of low density lipoproteins radiolabeled with oleyl cholesteryl ether [14C-CE]LDL (58% and 149% from control). Compounds I and II inhibited cholesterol biosynthesis from [14C]acetate (with IC50 values of 4.0 +/- 0.7 and 8.0 +/- 1.5 microM). Effects of compounds V and VI were less potent; compounds III and IV were inactive. Compound II activated cholesterol acylation, estimated by incorporation of [14C]-oleic acid into cholesteryl esters (170% from control at a concentration of 30 microM). The results indicate correlation between polarity of the compound and its ability to regulate cholesterol metabolism in Hep G2 cells.

[Antibodies against synthetic peptide fragments of T-cadherin inhibit binding of low density proteins with T-cadherin]. / Antitela protiv sinteticheskikh peptidnykh fragmentov T-kadgerina podavliaiut sviazyvanie lipoproteidov nizkoi plotnosti s T-kadgerinom.

Potential antigenic determinants of the atypical lipoprotein-binding proteins T-cadherin (p105) and its precursor (p130) from cells of human smooth muscles were synthesized by the solid phase method according to the Fmoc-scheme. These corresponded to the 51-61, 140-160, 161-179, 260-271, 340-352, 350-362, and 370-385 sequences of p130 and were chosen on the basis of computer analysis of its antigenic structure. The conjugates of the peptides with horseradish peroxidase were used for the immunization of mice and rabbits. Antisera against the peptides corresponding to the 140-160, 161-179, and 260-271 sequences of p105 were shown by immunoblotting to react with p105, which we isolated from the vascular cells of smooth muscles and earlier identified as T-cadherin. These antisera inhibited the binding of low density lipoproteins with p105 in a dose-dependent manner. These results confirmed the identification of the p105 protein as T-cadherin and demonstrated the fundamental possibility of studying the interaction of this protein with low density lipoproteins by using antipeptide antibodies that inhibit binding.

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.

[Immunodiagnosis of retinoblastoma]. / Ob immunodiagnostike retinoblastomy.

To improve the accuracy of early diagnosis of retinoblastoma, the authors have examined a number of cellular and humoral immunity parameters in 188 children with retinoblastomas, in 57 ones with nontumorous conditions of the eyes, and in healthy controls. Stages III-IV retinoblastoma was found associated with reduced blood levels of IgG and IgA and a still more marked reduction of both in the lacrimal fluid (4-fold), with reduced blood T lymphocyte count (by 1.5 times), decreased lymphocyte blastogenesis response to phytohemagglutinin (by 8-9 times), reduced leukocyte migration activity (MI = 79 +/- 10%), reduced serum thymic activity (by 2.5 times). The early (I-II) stage of the disease involves a lowering of only lacrimal fluid IgA (2-fold) and of the leukocyte migration index (MI) (89 +/- 2%). This index was found to be an important specific indicator for the early preoperative diagnosis of retinoblastoma. Leukocyte migration inhibition (MI less than 95%) by retinoblastoma antigens was observed only if this tumor was present. In cases with the nontumorous conditions and in health retinoblastoma antigens as a rule stimulated the leukocyte migration (MI over 95%).