Enhancement of an inhibitory input to the feeding central pattern generator in Lymnaea stagnalis during conditioned taste-aversion learning

To study the neuronal mechanism of a conditioned taste-aversion (CTA) learning in the pond snail Lymnaea stagnalis, we examined the synaptic connection between the neuron 1 medial (N1M) cell and the cerebral giant cell (CGC), the former is an interneuron in central pattern generator for the feeding response and the latter is a regulatory neuron to the central pattern generator. Inhibitory postsynaptic potential (IPSP) which was evoked in the N1M cell by activation of the CGC was larger and lasted longer in the conditioned animal than that in the control animal. The electrical properties of the cell body of CGC and the responses of the CGC to the chemosensory inputs were not changed during the CTA learning. These results, together with the previous report indicating the existence of excitatory projection from the N1M cell to the feeding motoneuron, suggest that enhanced IPSP in the N1M cell may underlie the suppression of feeding responses in the Lymnaea CTA learning.     

AN ELECTRON MICROSCOPIC STUDY ON THE RETICULOENDOTHELIAL CELLS IN THE LYMPH NODES

In an attempt to clarify the cytological characteristics of the RES cells in the lymph nodes and their embryological correlations, lymph nodes and lymph node anlages of germ-free rats, nude mice, and human fetuses were light and electron microscopically examined. On the basis of differences of intracellular organelles, their behaviors for reticulum fibers and of endogenous peroxidatic activity, histiocytes should be reasonably distinguished from the cells conventionally called reticulum cells. Reticulum cells and histiocytes respectively are destined to differentiate in different directions from the early stage of development of the lymph node anlage. Sinus endothelial cells are ontogenetically originated and differentiated from the endothelial lining cells of lymphatic vessels. Primitive reticular cells are differentiated into mature reticulum cells in the lymph nodes, they transform into the lympho-reticular cells, further into lymphoblasts, and finally develop into medium-sized lymphocytes.     

Regulation of inwardly rectifying K(+) channel in cultured opossum proximal tubule cells by protein phosphatases 1 and 2A

The inwardly rectifying ATP-regulated K(+) channel with an inward conductance of about 90 pS in the surface membrane of cultured opossum kidney proximal tubule (OKP) cells is activated at least in part by protein kinase A (PKA). In this study, we examined the effects of protein serine/threonine phosphatase types 1 (PP-1) and 2A (PP-2A) on activity of the K(+) channel using the patch-clamp technique. In cell-attached patches, channel activity was enhanced by the application of okadaic acid (OA, 1 microM), a membrane-permeable inhibitor of PP-1 and PP-2A, to the bath solution. This enhancement was abolished by the pretreatment of cells with KT5720 (200 nM), a specific inhibitor of PKA. In inside-out patches, channel activity which could be maintained in the presence of ATP (3 mM) in the bath solution was also increased by the addition of OA (1 microM), and the OA-induced increase in channel activity was partially prevented in the presence of KT5720 (200 nM). Direct application of either PP-1 (1 U/ml) or PP-2A (1 U/ml) to the cytoplasmic surface of the patch membrane inhibited channel activity maintained by ATP (3 mM) in inside-out patches. Moreover, channel activity stimulated by PKA (20 nM) in the presence of ATP (3 mM) was also inhibited by the application of either PP-1 (1 U/ml) or PP-2A (1 U/ml). These results indicate that the OA-sensitive protein phosphatase is involved in the regulation of channel activity, and suggest that both PP-1 and PP-2A are candidates responsible for the inhibition of channel activity through dephosphorylation of the PKA-mediated protein phosphorylation.     

GLOMERULAR TISSUE INJURY IN IgA NEPHRITIS

The glomerular lesions In 129 cases of IgA nephritis were analyzed. The development of glomerular injury occurred in two ways, one being a chronic mesangial depositive and sclerosing lesion commonly found in most glomeruli, and the other an acute but local injury initiating from the local peripheral glomerular basement membrane abnormality, i.e., thinning and/or splitting, which was seen at least in one third of all cases. The activation of the local coagulatory process could add segmental glomerular changes including small crescents, adhesion, and local tuft necrosis to the mesangial lesion. ACTA PATHOL. JPN. 33; 367–380, 1983.     

Alterations in Nonspecific Cross-reacting Antigen Localization during Cell Culture

Nonspecific cross reacting antigen (NCA), a constituent of the carcinoembryonic antigen family, was localized ultra-structurally in a human lung adenocarcinoma cell line, PC 9. NCA was distributed predominantly on the plasma membrane in the early phases of cell culture. Deletion of fetal bovine serum (FBS) from the culture medium suppressed cell division without significantly altering cell viability, and induced a dramatic but reversible change in NCA localization. Under these conditions, NCA was localized to membrane degradation products within cytoplasmic vesicles and vacuoles. Acid phosphatase activity was also present in some of these intracellular structures. Similar changes in NCA localization were seen in cells cultured with FBS at day 6 when the cells reached a plateau stage of growth. These findings strongly suggest that plasma membrane degradation is accelerated by the cessation of cell growth. Cytoplasmic reactivity for NCA in cancer cells may therefore reflect degradation of plasma membrane-associated NCA and may not necessarily be correlated with increased systhesis of this glycoprotein. Acta Pathol Jpn 39: 772 778, 1989.     

Properties of ipsilateral retinogeniculate afferents in albino and hooded rats

By recording single unit activities from the dorsal lateral geniculate nucleus in albino and hooded rats, physiological properties of the ipsilateral retinogeniculate afferents were compared with those of the contralateral ones. The results show that the ipsilateral retinogeniculate pathway was characterized by intermediate conduction velocities, relatively high incidence of the tonic response and the visual field representation of central 30° from the vertical midline on both sides.     

Ultrastructure of human pheochromocytoma cells cultured for long periods

We conducted ultrastructural analysis of human pheochromocytoma (PC) cells maintained in primary culture for about 10 months. The cells were first isolated by the enzymatic treatment of a surgically resected tissue specimen obtained from a 37-year-old man with PC, a condition which is characterized by elevated blood levels of adrenaline and noradrenaline. It was found that noradrenaline production in the medium continued until the 90th day of culture (1330 pg/ml). The production level decreased to 20 pg/ml on the 180th day, and to 18 pg/ml on the 300th day. Examination under a transmission electron microscope (TEM) at 4 weeks of culture revealed electron-dense granules (about 200 nm in size and, presumably, rich in catecholamines), which were also observed in the tumor cells from the original PC tissue. Neurite-like processes grew at around 1 week of culture, and were still maintained at 6 months of culture. But, after 6 months of culture, the neurite-like processes contained a rosary-like elevated structure, which was suggestive of cell degeneration, as determined by a plasma polymerization replica method and observed with a scanning electron microscope. When cells were examined under the TEM, fewer electron-dense granules were observed in the cell bodies, with more numerous lipofuscin-like granules and filaments. Thus, electron-dense granules, which, presumably, contain catecholamines, were seen in a long-term culture of human PC cells. These granules decreased in number in parallel with the decrease in catecholamine levels in the culture.     

IMMUNOHISTOCHEMICAL LOCALIZATION OF TYPE I, II, III, AND IV COLLAGENS IN THE LUNG

Type specific rabbit antibodies to bovine type I, 11, 111, and IV (basement membrane) collagens showing no cross-reaction with other types of collagen were prepared by cross-adsorption and diethylamiuoethyl-cellulose romatography. The antibodies to bovine type I and I11 collagens showed a high cross-reaction with the corresponding human collagens, but those to type I1 and IV collagens did moderate and no cross-reactions with human type I1 and IV collagens, respectively. By using these antibodies, tissue distribution of various types of collagen in normal bovine lung was examined by indirect immunofluorescence microscopy. Both type I and I11 collagens were found to distribute widely in the interstitium of bronchial tree, bronchial
lamina propria and of interlobules as well as alveolar nipples and adventitia of pulmonary arteries. Type I1 collagen was located only in bronchial cartilage. The tissues mainly stained for type 11 collagen were the alveolar interstitium (also stained faintly for type I collagen) and the intima and media of the arteries. Type IV collagen was located in a membranous fashion in alveolar septa and bronchial smooth muscles and subepithelial layers as well as capillaries and the intima and media of arteries. ACTA PATHOL. JPN. 31: 601–610, 1981.     

Reticular crypt epithelium and intra-epithelial lymphoid cells in the hyperplastic human palatine tonsil: An immunohistochemical analysis

Extensive immunohistochemical analyses of the hyperplastic human palatine tonsil disclosed variegated B cell phenotypes on the lymphoid cells among the crypt epithelium. The reticular epithelial network was evident by cytokeratin immunostaining. The reticular epithelium near the crypt Iumen was positive for Iysozyme. Secretory component was negative, while HLA-DR was frequently expressed. Intramucosal small Iymphocytes, densely distributed in the Iuminal side, consisted mainly of B cells expressing CD19, CD20, CD21, CD22, CD45R, CD74, DBB42, HLA-DR, HLA-DQ, bcl-2 protein and surface lgM. Some B cells revealed mantle zone phenotypes (surface IgD+, CD5+, CD24+, DBA44+, CD10^--, DNA7^--). Cells of germinocyte phenotype (CD10+, DNA7+) were sparsely seen. A good number of intramucosal lymphoid cells were further labeled for CD11b, a phenotype of so-called B-1 cells. Plasma cells were clustered within the basal half. IgG was their major immunoglobulin class, followed by IgA, IgM and lgD classes. A smaller number of T cells (CD2+, CD3+, CD5+, CD45RO+, TCR αβ+) were identified among the epithelium. CD4+ cells predominated over CD8+ cells. TCR γΔ + cells were rare. Macrophages (CD68+), dendritic histio-cytes (S-100 protein+, CD1+), and natural killer cells (CD16+ or CD57+) were also dispersed. Another unique feature of this lymphoepithelial complex was the existence of HLA-DR intramucosal microvasculature, where lymphocyte recirculation was suggested. Proliferating cell nuclear antigen was detected commonly in the epithelial cells but rarely in the lymphoid cells. Possible lymphoepithelial interactions and morphologic similarities to the thymic medulla are discussed.     

Vinyl polymerization. 294. Decomposition of tetramethyltetrazene in the presence of p-substituted benzyl chlorides

A study was made of the polymerization of acrylonitrile in dimethylformamide (DMF) initiated by the binary systems of tetramethyltetrazene (TMT) and p-substituted benzyl chlorides. The polymerization rate increased linearly with the σ-constants of substituents as electron-releasing groups were introduced to the phenyl ring of benzyl chloride. In order to elucidate the initiation mechanism of the polymerization, a kinetic investigation was also undertaken of the decomposition of TMT in the presence of p-substituted benzyl chlorides in DMF. The decomposition rate was first-order in TMT and first-order in p-substituents benzyl chloride. The decomposition rate also increased with the σ constants of substituents as electron-releasing groups were introduced. On the basis of the results, the initiation mechanism for the polymerization was discussed.