Electron microscopic examination of the lung of mice infected with a virulent strain of M. bovis (Ravenel) revealed marked alterations in the alveolar epithelial cells, particularly Type 2 cells (granular pneumocytes), in addition to the development of interstitial and intra-alveolar granuloma. Unlike the feature in uninfected mice, more than one Type 2 epithelial cells were often found adjacent to one another within a single alveolus. Some of these cells showed mitotic figures. Their characteristic lamellar inclusions were morphologically altered.

Animals↗

PubMed1979

Ultrastructural study of mycobacteria in experimentally produced lung lesions of mice.

Mice were infected by iv injection with a virulent strain of Mycobacterium bovis, Ravenel strain, to prepare specimens for electron microscopical observation of their intracellular morphology. Observation was made with ultra-thin sections of the granulomatous lungs at an advanced stage of infection. Many apparently intact bacterial cells were found intracellulary, and the majority of them had lipoidal inclusions enclosed by a membranous structure. Several layers of mycobacterial cell wall were discernible, including a fairly wide space of the electron-transparent zone just beneath the electrondense outmost layer. Mesosomes, nuclear material, small dense granules and cross wall were found in almost the same appearance as those reported of mycobacteria grown in vitro. The bacilli were located mainly within intact or damaged phagosomes which were often filled with amorphous material of various electron densities.

Animals↗

PubMed1979

Primary in vitro immunogenicity of liposomal model membranes in mouse spleen cell cultures.

Neither 2,4-dinitrophenyl-6-N-aminocaproylphosphatidylethanolamine (DNP-Cap-PE) nor fluoresceinthiocarbamylphosphatidylethanolamine (F1-PE) induces hapten-specific plaque-forming cells (PFC) when incubated with suspensions of spleen cells from unimmunized C57BL/6J mice. However, PFC are produced after incorporation of these synthetic lipid antigens into liposomal model membranes. The in vitro response is characterized by the following: a) it is time and dose dependent; b) the frequency of IgM PFC exceeds IgG PFC; c) both nonadherent and adherent cells are required (2-mercaptoethanol can replace the requirement for adherent cells in some experiments); d) depletion of thymus-derived cells by treatment with anti-theta antiserum plus complement does not diminish the response; e) spleen cells from nude BALB/c mice also produce PFC. Thus, the essential features of the in vivo immunogenicity of DNP-Cap-PE and F1-PE sensitized liposomes, which have been previously described, can be replicated in an in vitro cell culture system.

Aminocaproates↗

PubMed1978

Identification of a mutagenic substance in a spice, sumac, as quercetin.

The mutagenicity of a spice, sumac, was demonstrated on Salmonella typhimurium strain TA98. The active principle was purified and characterized by thin-layer chromatography, UV-absorption spectroscopy and mass spectrometry. All the mutagenic activity of sumac was found to be due to quercetin.

Chromatography, Thin Layer↗

PubMed1978

Association of virus specific replicative ribonucleic acid with nuclear membrane in chick embryo cells infected with japanese encephalitis virus.

Using high resolution electron microscopic autoradiography and velocity sedimentation, RNA synthesis was examined in chick embryo cells infected with Japanese encephalitis virus (JEV). RNA was labelled with 3H-uridine for 5 min or 10 min at 15 h after infection in the presence of actinomycin D and D-glucosamine. Microautoradiography showed significantly numbers of silver grains on the nuclear membranes of 5 min pulse-labelled thin cell sections. The RNA species in membrane fractions obtained from the nucleus and cytoplasm of the infected cells were analysed by sucrose density gradient sedimentation. Radioactive 23S replicative form RNA and 8-12S RNA were obtained from the outer membrane fractions of the nuclear envelope. Labelled 42S virus RNA was obtained from the fractions containing large vesicle membranes and plasma membranes. These results suggest that JEV-RNA synthesis is initiated in the perinuclear region in close association with the outer membranes of the nuclear envelope.

Animals↗

PubMed1978

Electrophysiological studies of two types of thalamo-cortical neurones and their responses to stimulation of mesencephalic reticular formation.

1. Thalamo-cortical (T-C) neurones projecting their axons to the motor cortex were recorded intra- or extra-cellularly in the anterior ventral and lateral ventral nuclear complex of the thalamus in lightly nembutalized cats. The T-C neurones were identified as responding antidromically to stimulation of the motor cortex, and were examined in connection with effects of stimulation of the centrum medianumparafascicular complex (CM), pallidum (Pal), cerebellar nuclei (CN) and mesencephalic reticular formation (RF). 2. The T-C neurones were classified into two groups, A and B. The A-group neurones responded neither to stimulation of CM nor to that of Pal. By contrast, the B-group neurones were activated from either CM, Pal or both. The effect of RF stimulation was facilitatory in many of the A-group neurones whereas it was mostly inhibitory in the B-group neurones. CN stimulation activated most of the T-C neurones in both A and B groups. 3. The A-group neurones were categorized as the deep T-C neurones mediating the deep T-C response of the cortex (the early surface-positive-deep-negative component of the augmenting response) and the B-group neurones as the superficial T-C neurones mediating the superficial T-C response of the cortex (the recruiting response and the late surface-negative-deep-positive component of the augmenting response). Desynchronization of electrocorticograms in response to RF stimulation was suggested to result from inhibition of the superficial T-C neurones and facilitation of the deep T-C neurones.

Action Potentials↗

PubMed1978

Effect of liposomal model membrane composition on immunogenicity.

We have examined the effect of composition on the immunogenicity in mice of liposomal model membranes sensitized with dinitrophenyl-epsilon-aminocaproyl-phosphatidylethanolamine (DNP-Cap-PE) derivatives. Neither cholesterol content nor incorporation of exogenous charged amphiphile (dicetylphosphate, stearylamine) exerted a significant influence on the in vivo anti-DNP response as measured by the appearance of direct plaque-forming cells in the spleen. Similarly, the nature of the fatty acids (saturated vs unsaturated) present in DNP-Cap-PE had no effect. In contrast, the nonpolar region of the basic phospholipids comprising the liposomal bilayers played an important role as revealed by a comparative study of model membranes prepared with beef sphingomyelin (SM), egg phosphatidylcholine (PC), and synthetic distearoyl-, dimyristoyl-, dilauroyl-, and dioleoyl-phosphatidylcholines (DSPC, DMPC, DLPC, DOPC). Thus, liposomes with a large content of phospholipids possessing a high transition temperature (e.g., beef SM, DSPC) were more immunogenic than those containing phospholipids of low transition temperature (e.g., egg PC, DOPC). This correlation held for both unsonicated and sonicated liposomes. These findings may have a bearing on the phenomenon of membrane-localized antigen expression.

Animals↗

PubMed1978