Immunodepressive action of carminomycin and rubomycin derivatives]

The immunodepressive effects of carminomycin and its 3 semi-synthetic derivatives, as well as rubomycin and its derivative R-103 were compared. It was found that 14-hydroxycarminomycin was much superior to the other substances in the experiments with synthesis induction suppression of antibodies against sheep red cells in mice. Suppression of the rejection of the skin allogenic grafts in the mice by carminomycin was higher as compared to that by the other substances. Probably different populations of the immune competent cells have selective sensitivity to separate anthracyclines.     

Rapid change in the dynamics of antibody-forming cells under the influence of a single injection of various anthracyclines

The dynamics of the titers and number of the antibody forming cells was studied within 26 hours after a single injection of anthracycline to immunized animals at various phases of the immune response. The specificity of the "rapid" effect of anthracyclines suggests that the low differentiated precursors of the antibody forming cells are the main target for the rubomycin effect and the immune competent cells in the state of multiplication and differentiation under the effect of the antigen are the main target for the carminomycin effect. The study was performed with noninbred mice immunized with sheep red cells.     

Production of biologically active recombinant human soluble CD23 and its effect on PBMCs isolated from hyper-IgE blood

A recombinant form of human soluble CD23 (sCD23), the low affinity receptor for IgE (FcepsilonRII), was produced by PCR cloning the lectin-binding domain sequence into a bacterial expression vector. After renaturation and purification, the sCD23 bound IgE and divalent metal ions, indicating its activity. The recombinant human sCD23 exhibited similar proinflammatory properties as the native protein. Although interleukin-1beta, tumour necrosis factor-alpha, and nuclear factor-kappaB appeared not to be enhanced significantly in unstimulated RPMI 8866 B-lymphoblastoid and U937 promonocytic cell lines with 24 h incubation of recombinant sCD23, they were produced in both healthy and hyper-IgE-derived peripheral blood mononuclear cells, especially tumour necrosis factor-alpha. This study concludes that while recombinant and chimeric sCD23 may be useful in blocking IgE binding to immune cells and decreasing IgE synthesis by B-lymphocytes, the production of proinflammatory cytokines, particularly tumour necrosis factor-alpha will enhance immune responses in cases of asthma, allergy, and hyper-IgE syndrome.     

Instrumental behavior in the activation or blockade of the neostriatum muscarinic receptors

In four dogs, microinjections of carbacholine enhanced the tonic component and inhibited the physical component of the instrumental defence reflex, put in order the posture, and increased its components' amplitude. Microinjections of raclopride yielded a similar though a less obvious result. Differentiation stimuli provided the greatest effect of both substances. A sharp improvement occurred in differentiation of sound signals. Microinjections of pyrenzepine yielded an opposite result. The data obtained are explained proceeding from the idea of a presence of the neostriatum's two efferent outputs exerting opposite effects on their targets, and the role of muscarine and dopamine receptors in their triggering and blockade.     

Tracking Down Biotransformation to the Genetic Level: Identification of a Highly Flexible Glycosyltransferase from Saccharothrix espanaensis

Saccharothrix espanaensis is a member of the order Actinomycetales. The genome of the strain has been sequenced recently, revealing 106 glycosyltransferase genes. In this paper, we report the detection of a glycosyltransferase from Saccharothrix espanaensis which is able to rhamnosylate different phenolic compounds targeting different positions of the molecules. The gene encoding the flexible glycosyltransferase is not located close to a natural product biosynthetic gene cluster. Therefore, the native function of this enzyme might be not the biosynthesis of a secondary metabolite but the glycosylation of internal and external natural products as part of a defense mechanism.     

A Human Anti-M2 Antibody Mediates Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) and Cytokine Secretion by Resting and Cytokine-Preactivated Natural Killer (NK) Cells

The highly conserved matrix protein 2 (M2) is a good candidate for the development of a broadly protective influenza vaccine that induces long-lasting immunity. In animal models, natural killer (NK) cells have been proposed to play an important role in the protection provided by M2-based vaccines through a mechanism of antibody-dependent cell-mediated cytotoxicity (ADCC). We investigated the ability of the human anti-M2 Ab1-10 monoclonal antibody (mAb) to activate human NK cells. They mediated ADCC against M2-expressing cells in the presence of Ab1-10 mAb. Furthermore, NK cell pro-inflammatory cytokine and chemokine secretion is also enhanced when Ab1-10 mAb is present. We also generated cytokine-preactivated NK cells and showed that they still displayed increased effector functions in the presence of Ab1-10 mAb. Thus, our study has demonstrated that human resting and cytokine-preactivated NK cells may have a very important role in the protection provided by anti-M2 Abs.     

The Saccharomyces cerevisiae Dna2 can function as a sole nuclease in the processing of Okazaki fragments in DNA replication

During DNA replication, synthesis of the lagging strand occurs in stretches termed Okazaki fragments. Before adjacent fragments are ligated, any flaps resulting from the displacement of the 5′ DNA end of the Okazaki fragment must be cleaved. Previously, Dna2 was implicated to function upstream of flap endonuclease 1 (Fen1 or Rad27) in the processing of long flaps bound by the replication protein A (RPA). Here we show that Dna2 efficiently cleaves long DNA flaps exactly at or directly adjacent to the base. A fraction of the flaps cleaved by Dna2 can be immediately ligated. When coupled with DNA replication, the flap processing activity of Dna2 leads to a nearly complete Okazaki fragment maturation at sub-nanomolar Dna2 concentrations. Our results indicate that a subsequent nucleolytic activity of Fen1 is not required in most cases. In contrast Dna2 is completely incapable to cleave short flaps. We show that also Dna2, like Fen1, interacts with proliferating cell nuclear antigen (PCNA). We propose a model where Dna2 alone is responsible for cleaving of RPA-bound long flaps, while Fen1 or exonuclease 1 (Exo1) cleave short flaps. Our results argue that Dna2 can function in a separate, rather than in a Fen1-dependent pathway.     

Compression and dilation of the membrane-cortex layer generates rapid changes in cell shape

Rapid changes in cellular morphology require a cell body that is highly flexible yet retains sufficient strength to maintain structural integrity. We present a mechanism that meets both of these requirements. We demonstrate that compression (folding) and subsequent dilation (unfolding) of the coupled plasma membrane–cortex layer generates rapid shape transformations in rounded cells. Two- and three-dimensional live-cell images showed that the cyclic process of membrane-cortex compression and dilation resulted in a traveling wave of cortical actin density. We also demonstrate that the membrane-cortex traveling wave led to amoeboid-like cell migration. The compression–dilation hypothesis offers a mechanism for large-scale cell shape transformations that is complementary to blebbing, where the plasma membrane detaches from the actin cortex and is initially unsupported when the bleb extends as a result of cytosolic pressure. Our findings provide insight into the mechanisms that drive the rapid morphological changes that occur in many physiological contexts, such as amoeboid migration and cytokinesis.     

Hypervariable Domain of Nonstructural Protein nsP3 of Venezuelan Equine Encephalitis Virus Determines Cell-Specific Mode of Virus Replication

Venezuelan equine encephalitis virus (VEEV) is one of the most pathogenic members of the Alphavirus genus in the Togaviridae family. This genus is divided into the Old World and New World alphaviruses, which demonstrate profound differences in pathogenesis, replication, and virus-host interactions. VEEV is a representative member of the New World alphaviruses. The biology of this virus is still insufficiently understood, particularly the function of its nonstructural proteins in RNA replication and modification of the intracellular environment. One of these nonstructural proteins, nsP3, contains a hypervariable domain (HVD), which demonstrates very low overall similarity between different alphaviruses, suggesting the possibility of its function in virus adaptation to different hosts and vectors. The results of our study demonstrate the following. (i) Phosphorylation of the VEEV nsP3-specific HVD does not play a critical role in virus replication in cells of vertebrate origin but is important for virus replication in mosquito cells. (ii) The VEEV HVD is not required for viral RNA replication in the highly permissive BHK-21 cell line. In fact, it can be either completely deleted or replaced by a heterologous protein sequence. These variants require only one or two additional adaptive mutations in nsP3 and/or nsP2 proteins to achieve an efficiently replicating phenotype. (iii) However, the carboxy-terminal repeat in the VEEV HVD is indispensable for VEEV replication in the cell lines other than BHK-21 and plays a critical role in formation of VEEV-specific cytoplasmic protein complexes. Natural VEEV variants retain at least one of the repeated elements in their nsP3 HVDs.     

Identification of drugs including a dopamine receptor antagonist that selectively target cancer stem cells

Selective targeting of cancer stem cells (CSCs) offers promise for a new generation of therapeutics. However, assays for both human CSCs and normal stem cells that are amenable to robust biological screens are limited. Using a discovery platform that reveals differences between neoplastic and normal human pluripotent stem cells (hPSC), we identify small molecules from libraries of known compounds that induce differentiation to overcome neoplastic self-renewal. Surprisingly, thioridazine, an antipsychotic drug, selectively targets the neoplastic cells, and impairs human somatic CSCs capable of in vivo leukemic disease initiation while having no effect on normal blood SCs. The drug antagonizes dopamine receptors that are expressed on CSCs and on breast cancer cells as well. These results suggest that dopamine receptors may serve as a biomarker for diverse malignancies, demonstrate the utility of using neoplastic hPSCs for identifying CSC-targeting drugs, and provide support for the use of differentiation as a therapeutic strategy.