Structure and function of the perinucleolar compartment in cancer cells.

The perinucleolar compartment (PNC) is a subnuclear body that forms in cancer cells. In vivo analyses using human tumor tissues demonstrate a close correlation between PNC prevalence and disease progress in colorectal carcinoma, and a high PNC prevalence is associated with poor patient outcome. These findings are consistent with previous observations in breast cancer and cancer cell lines in vitro. The PNC is composed of thick strands that form a filamental meshwork often extending into the nucleolus. Although it appears to be electron dense as observed by transmission electron microscopy (TEM), the actual density of the structure imaged by electron spectroscopy is much lower, similar to that of the interchromatin space, and is lined with ribonucleoproteins (RNPs). In situ detections show that the PNC is highly enriched with a subset of small RNAs of polymerase III (Pol III) origins and RNA-binding proteins primarily implicated in pre-mRNA processing. A novel gel-shifting approach demonstrates that the addition of PNC-associated RNAs into HeLa cell lysates increases the mobility of polypyrimidine tract-binding (PTB) protein in a native gel electrophoresis, suggesting an interaction between these RNAs and PTB proteins. On the basis of these and other findings, we propose a working model in which novel RNPs have a key role in regulating gene expression at the PNC in cancer cells.

Distribution of cholinergic cells in guinea pig brainstem.

We used an antibody to choline acetyltransferase (ChAT) to label cholinergic cells in guinea pig brainstem. ChAT-immunoreactive (IR) cells comprise several prominent groups, including the pedunculopontine tegmental nucleus, laterodorsal tegmental nucleus, and parabigeminal nucleus, as well as the cranial nerve somatic motor and parasympathetic nuclei. Additional concentrations are present in the parabrachial nuclei and superior colliculus. Among auditory nuclei, the majority of ChAT-IR cells are in the superior olive, particularly in and around the lateral superior olive, the ventral nucleus of the trapezoid body and the superior paraolivary nucleus. A discrete group of ChAT-IR cells is located in the sagulum, and additional cells are scattered in the nucleus of the brachium of the inferior colliculus. A group of ChAT-IR cells lies dorsal to the dorsal nucleus of the lateral lemniscus. A few ChAT-IR cells are found in the cochlear nucleus and the ventral nucleus of the lateral lemniscus. The distribution of cholinergic cells in guinea pigs is largely similar to that of other species; differences occur mainly in cell groups that have few ChAT-IR cells. The results provide a basis for further studies to characterize the connections of these cholinergic groups.

Early GABA(A) receptor clustering during the development of the rostral nucleus of the solitary tract.

While there is an abundance of gamma-aminobutyric acid (GABA) in the gustatory zone of the nucleus of the solitary tract of the perinatal rat, we know that GABAergic synapse formation is not complete until well after birth. Our recent results have shown that GABA(B) receptors are present at birth in the cells of the nucleus; however, they do not redistribute and cluster at synaptic sites until after PND10. The present study examined the time course of appearance and redistribution of GABA(A) receptors in the nucleus. GABA(A) receptors were also present at birth. However, in comparison to GABA(B) receptors, GABA(A) receptors underwent an earlier translocation to synaptic sites. Extrasynaptic label, for example, of GABA(A) receptors was non-existent compared to GABA(B) receptors at PND10 and well-defined clusters of GABA(A) receptors could be seen as early as PND1. We propose that while GABA(A), receptors may play an early neurotransmitter role at the synapse, GABA(B) receptors may play a non-transmitter neurotrophic role.

Relations between Fc epsilon RI crosslinking-induced mast cell activation and adhesion to fibronectin.

Demonstration of murine mast cell adhesion to fibronectin (FN) following PMA-mediated cell activation raised the question whether crosslinking of high affinity IgE receptors on mouse mast cells might induce changes in adhesiveness of these cells to FN. Murine mast cells of line MCP5/L were used to investigate the effect of antigenic stimulation on cell adhesion to fN and mediator secretion. effect of antigenic stimulation on cell adhesion to FN and mediator secretion. Adhesion assays were performed using sensitized radiolabeled cells and FN- or BSA-coated 96-well plates. The presence of antigen in the concentrations up to 10 ng/ml resulted in concentration-dependent adhesion potentiation, which was detectable after 5 min, reached maximum at 30 min and persisted or decreased over the next 30 min. Adhesion potentiation decreased at antigen excess and was abolished by heat inactivation of IgE in the antiserum prior to cell treatment. External calcium ion and temperature dependence of adhesion together with the observation that RGD (Arg, Gly, Asp)--containing peptide blocked cell binding to FN suggests that FC epsilon RI crosslinking-induced adhesion potentiation involves an integrin type receptor on cell surface. Sensitized mast cells allowed to adhere spontaneously to FN released more histamine and beta-hexosaminidase upon antigen challenge. Hence, the results show the relations between IgE-induced mast cell activation, adhesion to FN and mediator secretion.

Influence of Tolpa Peat Preparation on the IgE-induced anaphylactic reactions in mice.

The ability of Tolpa Peat Preparation (TPP) to affect anaphylactic sensitization and mast cell secretory function was tested in BALB/c mice treated with TPP orally for 12 days. TPP in the doses of 20 and 50 mg/kg/day reduced histamine release from mouse peritoneal mast cells challenged with anti-IgE or concanavalin A in vitro. The treatment of mice with TPP from day 1 to day 12 of immunization with Ovalbumin (OA) absorbed on aluminium hydroxide gel resulted in a decrease of antigen-induced histamine release from mast cells of these mice in vitro and in decreased IgE antibody level in their sera. TPP introduced into OA-immunized mice showing developed IgE antibody response was less effective in decreasing anaphylactic histamine release from mast cells of these mice. In all experiments low doses of TPP used for oral treatment were more effective than high doses in inhibiting anaphylactic events in the mice.

Ultrastructure and some biological properties of influenza A virus. IV. Effect of proteolytic enzymes on viral particle.

Influenza virus strain A/USSR/053/74/H3N2 was subjected to the effect of soluble and nonsoluble trypsin. Both enzymes appeared to affect the activity of neuraminidase. The viruses altered in this way did not induce interferon (IFN) in mice. Treatment of viral particles with soluble bromeline brought about almost complete inactivation of hemagglutinin and slight suppression of neuraminidase activity. This virus was capable of IFN induction. On the other hand, when nonsoluble bromeline was used as the treatment agent, complete inactivation of neuraminidase and reduction of hemagglutinin titer were observed. This virus was not capable of IFN induction. Viral preparations treated with pronase, trypsin and bromeline for a total extraction of the surface antigens, did not induce IFN. The viruses treated with these enzymes were examined under the electron microscope. Trypsin-treated viruses showed no changes on their surface while bromeline and pronase totally extracted the spikes of surface antigens.