Detection of highly conductive surface electron states in topological crystalline insulators Pb(1-x)SnxSe using laser terahertz radiation.

We suggest a method for detection of highly conductive surface electron states including topological ones. The method is based on measurements of the photoelectromagnetic effect using terahertz laser pulses. In contrast to conventional transport measurements, the method is not sensitive to the bulk conductivity. The method is demonstrated on an example of topological crystalline insulators Pb(1-x)SnxSe. It is shown that highly conductive surface electron states are present in Pb(1-x)SnxSe both in the inverse and direct electron energy spectrum.

Cytotoxic and Immunochemical Properties of Viscumin Encapsulated in Polylactide Microparticles.

Biodegradable polylactide microparticles with encapsulated cytotoxic protein viscumin were obtained via the ultrasound-assisted supercritical fluid technique. The size of the microparticles was 10-50 µM, as shown by electron microscopy. The time course of viscumin release from microparticles was studied using an immunoenzyme test system with anti-viscumin monoclonal antibodies. It was found that 99.91% of the cytotoxic protein was incorporated into polymer microparticles. Only 0.08% of the initially encapsulated viscumin was released from the microparticles following incubation for 120 h in a phosphate-buffered saline at neutral pH. Importantly, the method of ultrasonic dry supercritical fluid encapsulation failed to alter both the cytotoxic potency and the immunochemical properties of the encapsulated viscumin. Thus, this procedure can be used to generate biodegradable polylactide microparticles with encapsulated bioactive substances.

[Structural features of proteins by intermittent-contact atomic force microscopy]. / Issledovanie strukturnykh osobennostei belkov preryvisto-kontaktnym metodom atomno-silovoi mikroskopii.

Optimal conditions of protein scanning by atomic force microscopy were developed. Proteins of different molecular masses (950-11.5 kDa) and different three-dimensional organization were used to investigate the structural features of proteins. The most distinct images of proteins were obtained using a tip with the free amplitude in the range of 5-15 nm and with the set-point amplitude in the regime of repulsion from the sample. The method allowed one to clearly recognize the structural details of large molecules such as immunoglobulins IgM and IgG1 and Ricinus agglutinin. The revealing of the structural properties of proteins with molecular masses of 60 kDa and less was limited by the sharpness of probe tips used in the present study. It was shown that, by a quantitative analysis of the geometric parameters of molecules, it is possible to distinguish IgG1, Ricinus agglutinin, and ricin.

[Analysis of major antigenic determinants in Mistletoe lectin I]. / Analiz osnovnykh antigennykh determinant Mistletoe lectin I.

Antigenic determinants of Mistletoe Lectin I, a toxin from Viscum album were predicted on the basis of the primary amino acid sequence of the protein. Based on the results of analysis, the peptide FPGGSTRTQARS, which corresponds to the 144-155 segment of the viscumin A-chain, was synthesized. The peptide was tested in enzyme-linked immunosorbent assay with monoclonal antibodies against the viscumin A-chain obtained previously. The peptide reacted with antibodies with a low affinity and did not inhibit the binding of viscumin molecule to any of the antibodies. Analysis of the peptide by 1H-NMR spectroscopy in aqueous solution was performed. The three-dimensional structure of the 144-155 segment in the native protein globule was shown.

[Biochemical study of the A2F4 antigen associated with human pulmonary adenocarcinoma]. / Biokhimicheskoe izuchenie antigena A2F4, assotsiirovannogo s adenokartsinomoi legkogo cheloveka.

The tissue-specific antigen associated with human lung adenocarcinoma had been investigated using immunological and biochemical methods. The antigen, which represents a new tissue-specific marker, has a molecular weight of 400 kDa. Purification of the antigen was achieved by gel chromatography. Antibody binding to the antigen was studied using enzyme-linked immunoassay after preincubation with enzymes or treatment with periodate. The results obtained testify to the proteinaceous nature of the antigenic determinant and the glycoprotein nature of the antigen.

[Goblet cell antigen revealed by monoclonal antibody D12]. / Antigen bokalovidnykh kletok, vyiavliaemyi monoklonal'nymi antitelami D12.

An antigen from meconium was revealed by monoclonal antibody D 12 (IgM). This antigen was heat liable substance with relative m. m. about 400-600 kD. Reactions on histological slides with MAb D 12 were blocked up after processing tissues by neuraminidase and become stronger after processing tissues by NaIO4. Antigen D 12 was found in goblet cells of fetal and definitive colon and in analogous cells of trachea and bronchi.

[Immunohistochemical study of meconial antigens in neoplasms and mucosa of the colon and rectum]. / Immunogistokhimicheskoe izuchenie mekonial'nykh antigenov v novoobrazovaniiakh i slizistoi obolochke tolstoi i priamoi kishok.

The expression of 4 meconial antigens--beta-1-MA, beta-2-MA, MMA, gamma-MA in neoplastic and preneoplastic colonic mucosa was studied. Meconial antigens were revealed in small amount in adult normal colonic epithelium. The mucosa adjacent to tumours was rich in these antigens. Cellular localization of meconial antigens in these parts of colonic mucosa was similar to that of embryonal alimentary tract. beta-1-MA was found in 96%, beta-2-MA--73.6%, MMA--82.8%, gamma-MA--31.8% of colonic carcinomas.

Photodestruction in vitro of tumour cells sensitized by porphyrins and their conjugates with specific antibodies.

The photodynamic action of a number of carboxylic porphyrins and their covalent conjugates with specific monoclonal IgM antibodies on a human lung adenocarcinoma cell line was studied. All the conjugates showed strong phototoxicity which did not correspond with the phototoxicity of the free porphyrins. Absolute quantum yields of singlet oxygen photogeneration by the porphyrins and their conjugates were obtained and compared with the phototoxicity of the compounds.

[Tissue specificity of monoclonal antibodies to cells of human pulmonary adenocarcinoma]. / Izuchenie tkanespetsifichnosti monoklonal'nykh antitel k kletkam adenokartsinomy legkogo cheloveka.

Immunohistological localization of antigens revealed by 5 MoAbs to human lung adenocarcinoma cell line was studied by indirect immunoperoxidase technique. One of the MoAbs--A2F4--showed a relative specificity to epithelial tissues having a glandular differentiation. Except approximately 50% of normal cells of lungs and those of pulmonary tumours (mostly adenocarcinomas) they reacted with some other normal (stomach, oesophagus, breast) and tumoral (gastric, mammary and colonic) tissue cells. Other four MoAbs reacted with the much larger number of cells including some nonepithelial (granulocytes and histiocytes) ones.

[Immunohistological study of pulmonary adenocarcinoma using monoclonal antibodies]. / Immunogistologicheskoe izuchenie adenokartsinomy legkogo s pomoshch'iu monoklonal'nykh antitel.

Immunohistochemical methods were used to identify A2F4 monoclonal antibodies raised by immunization of animals with a human lung adenocarcinoma cell line in 17 lung adenocarcinomas and five pulmonary metastases of other origin. The antigen identified by the antibodies was registered in 53% of lung adenocarcinomas. Localization of the pulmonary antigen was compared with that of the carcinoembryonic antigen. The expression of the antigens proved different.

[Tissue-specific mammary gland antigen identified by monoclonal antibodies]. / Tkanespetsificheskii antigen molochnoi zhelezy, identifitsitrovannyi monoklonal'nymi antitelami.

A new antigen of mammary tumor cells has been revealed using monoclonal antibodies. A similar antigen was detected also in certain types of secretory epithelia of oesophagus, stomach, salivary gland, and embryonic large intestine. Upon malignization, antigen persists in invasive ductal cancer of mammary gland and is expressed in cancers of ovary and rectum. The molecular weight of the antigen is greater than 2,000 kD.

The effect of idiotype-specific and anti-ACA-1 sera on T cell subpopulations responding to H-2 antigens.

A xenogeneic anti-CBA-anti-C57BL/6 idiotype-specific serum reacted specifically only with CBA anti-C57BL/6 T cells. It inhibited T killers, T lymphocytes proliferating in one-way MLC and T cells which take part in the rejection of the cardiac allografts. However, it did not affect T suppressors and T MIF producers. Another antiserum, directed against ACA-1 (activated cell antigen), inhibited T killers of various specificities, but not T suppressors or T MIF producers. These results allow us to suggest that (1) the idiotype-like structures of T suppressors and T MIF producers differ from those of other T cell subpopulations responding to H-2 antigens; (2) ACA-1 is expressed on the surface of T killers, but not on T suppressors or T MIF producers; (3) T cells producing MIF form a separate subpopulation.

[Idiotype-specific inactivation by xenogeneic antisera of T killers but not of T-MIF producers immune to H-2 complex antigens]. / Idiotipospetsificheskaia inaktivatsiia ksenogennymi antisyvorotkami T-killerov, no ne T-MIF-produtsentov, immunnykh k antigenam kompleksa H-2.

Following appropriate absorption rabbit serum to CBA anti-C57BL/6 lymph node cells (rabbit ISS) and rat serum to enriched CBA anti-C57BL/6 T killers (rat ISS) selectively inhibited the activity of K-anti-b T killers but did not affect T killers of other specificities (K-anti-d, d-anti-b). Rabbit ISS did not suppress the capacity of CBA anti-C57BL/6 (K-anti-b) T cells to produce MIF. Under the same conditions, anti-Thy-1.2 serum inactivated killers and K-anti-b MIF-producers. The findings indicate that the killers and MIF-producers immune to the antigens of H-2 complex constitute different subpopulations of T cells, which appear to carry nonidentical sets of idiotypes.

[Production of heterologous antibodies to T-killers of mice immunized against H-2 antigens]. / Poluchenie geterologichnykh antitel k T-killeram myshei, immunnym k antigenam H-2.

Rabbit antisera were obtained against cytotoxic small peritoneal lymphocytes (IPEL) of CBA (H-2k) mice immune to alloantigens C57BL/6 (H-2b) and to the enriched 5-day MLC cytotoxic blast lymphocytes (MLC--CL). After appropriate absorption by cells and tissues of intact mice the cytotoxicity of the sera was lost relative to normal lymphoid cells. The absorbed anti-CPL serum inhibited, in the presence of complement, the cytotoxic effect of CPL but not that of MLC--CL on 51Cr-labeled allogeneic macrophages. This inhibition was restricted by idiotypic and strain specificity. Conversely, the absorbed anti-MLC--CL serum inhibited the cytotoxic effect of both CPL and MLC--CL of various mouse strains, irrespective of their immunologic specificity. It is supposed that the effect of the anti-CPL serum is mainly caused by antibodies againts idiotypic determinants of the killer T receptors, whereas the effect of the anti-MLC--CL serum is due to antibodies against differentiation antigens of the proliferating lymphocytes.

[Cross reactions in the H-2 system of cytotoxic T-lymphocytes concentrated by the adsorption-elution method on target cell monolayers]. / Perekrestnye reaktsii v sisteme H-2 tsitotoksicheskikh T-limfotsitov, kontsentrirovannykh metodom adsorbtsii-éliutsii na monosloe kletok-mishenei.

Cytotoxic T-lymphocytes (CTL) obtained by in vivo immunization were enriched by the absorption-elution technique, using the relevant allogeneic target cell (TC) monolayers. After the separation of C57BL anti-A (anti-KkDd) lymphocytes into anti-Kk and anti-Dd subpopulations they displayed cross killing cytotoxic effect on H-2d and H-2kTC, respectively. B10D2 anti-B10 (anti-KbDd) lymphocytes cross reacted to H-2a and H-2q TC. The results are discussed in the light of heterogeneity of CTL clones or their receptors.

Cross-reactivity of cytotoxic T-lymphocyte antigen-binding receptors immune to antigens of the H-2 system.

Anti-B10 D2 (anti-KbDb) cytotoxic T lymphocytes (CTL) and monospecific anti-Kk and anti-Dd CTL, separated from their mixture in anti-A B10 lymphocytes and concentrated with the absorption-elution technique on the macrophage monolayers of various genotypes, gave rise to cross-lysis of third-party target cells. Anti-B6 R101 (anti-Kb) CTL, which display a cross-lysis of mutant Kbd (M505) and Kba (Hzl) target cells, were separated into two fractions, one of them being able and the other unable to adhere to the cell monolayer of the particular mutant. The fraction of anti-Kb CTL adherent to Kba antigen was isolated by elution from the Hzl cell monolayer. These anti-Kba CTL and CTL eluted from the B6 cell monolayer displayed a considerably higher cytotoxic effect on B6 than on Hzl target cells. This difference was not due to lower sensitivity of Hzl targets to lysis. The findings indicate that anti-Kb CTL are homogeneous in the specificity of their receptors. The H-2 molecule is presumed to bear a single CTL determinant only, which induces a CTL clone or a group of clones homogeneous in specificity but heterogeneous in the affinity of its receptors.