Epithelial supporting cells can differentiate into outer hair cells and Deiters' cells in the cultured organ of Corti

The organ of Corti is a complex structure containing a single row of inner hair cells (IHCs) and three rows of outer hair cells (OHCs), supported respectively by one row of inner phalangeal cells and three rows of Deiters' cells. When fetal rat organ of Corti explants are cultured, supernumerary OHCs and supernumerary Deiters' cells are produced, without any additional cell proliferation. Analysis of semi- and ultrathin sections revealed that supernumerary OHCs are produced at the distal edge of the organ of Corti. Quantitative analysis of cell types present in the organ of Corti demonstrates that when the number of OHCs increases: (i) the total number of cells remains constant; (ii) the number of Deiters' cells increases; (iii) the number of tectal cells decreases and of Hensen's cells decreases. Using specific HC markers, i.e. jagged2 (Jag2) and Math1, we showed that in addition to existing OHCs, supernumerary OHCs, tectal cells and Hensen's cells expressed these markers in embryonic day 19 organ of Corti explants after 5 days in vitro. The results of this study suggest that Hensen's cells retain the capacity to differentiate into either tectal cells, which differentiate into OHCs, or into undertectal cells which differentiate into Deiters' cells. Received 15 May 2002; received after revision 18 July 2002; accepted 7 August 2002 RID="*" ID="*"Corresponding author.     

Mast cells in bronchial connective tissue of man importance of such cells in allergic tissue injury

Riassunto I mastociti, assai numerosi nel tessuto connettivo bronchiale umano normale, presentano in questo stesso distretto organico importanti modificazioni numeriche, morfologiche e istochimiche dopo trattamento con desametazone e nel corso di lesioni bronchiali di tipo disergico (asma bronchiale). Le alterazioni costantemente osservate negli asmatici fanno ritenere che esistano strette relazioni tra comportamento dei mastociti tessutali e manifestazioni disreattive dell'albero bronchiale.     

Motility of leukocytes in slide cells

Zusammenfassung Die Leukozytenbewegung wurde in Glaskammern während 24 h Inkubation beobachtet: die Kurve der Leukozytenbewegung besteht aus 2 Phasen, welche mittels 2 Exponentialgleichungen (durch das Wachstumsgesetz bestimmt) ausgedrückt werden können.In der vierten Stunde der Inkubation tritt eine Steigerung der Leukozytenbewegung auf.Die Leukozytenbewegung bei einer Temperatur von 30 und 40°C wurde mit der bei 37°C verglichen: Die Leukozytenbewegung ist bei 30°C langsamer und bei 40°C schneller als bei 37°C.     

Maintenance of visual cells in vitro

Résumé Des fragments de rétine et des cellules visuelles isolées de la grenouilleRana pipiens ont été cultivés dans la chambre de Rose. Bien qu'une dégénérescence morphologique des segments extérieurs des cellules visuelles ait été observée pendant la culture, le pouvoir de réfraction normal et la présence du pigment visuel ont été constatés dans ces segments, les segments intérieurs avec leurs noyaux étant conservés. Mais, l'intensité du pigment visuel a été plus faible que dans la rétine fraîche. Ces résultats montrent que la cellule individuelle du photorécepteur se prête à l'étude physiologiquein vitro.

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Aided by a grant from the National Society for the Prevention of Blindness.     

Protein farnesylation in mammalian cells: effects of farnesyltransferase inhibitors on cancer cells

Protein farnesylation, catalyzed by protein farnesyltransferase, plays important roles in the membrane association and protein-protein interaction of a number of eukaryotic proteins. Recent development of farnesyltransferase inhibitors (FTIs) has led to further insight into the biological significance of farnesylation in cancer cells. A number of reports point to the dramatic effects FTIs exert on cancer cells. In addition to inhibiting anchorage-independent growth, FTIs cause changes in the cell cycle either at the G1/S or at the G2/M phase. Furthermore, induction of apoptosis by FTIs has been reported. FTIs also affects the actin cytoskeleton and cell morphology. This review summarizes these reports and discusses implications for farnesylated proteins responsible for these FTI effects. Received 17 April 2001; received after revision 28 May 2001; accepted 28 May 2001     

Degranulating activity in hybrid cells derived from rat peritoneal mast cells and ehrlich ascites tumor cells

Summary Fusion of rat mast cells and Ehrlich ascites tumor cells was mediated by HVJ. Compound 48/80-induced degranulation occurred in the fused cells formed from two mast cells and one tumor cell, but not in the fused cells from one mast cell and two or more tumor cells.I am grateful to DrK. Utsumi for valuable discussions and for the donation of HVJ.     

Compared expression of murine plasmacytoma associated virus in tumor cells and in mouse embryo cells]

A DNA complementary to the viral genome of C-type particles produced by a Mouse myeloma derived cell line (MF2 cell line) was synthesized. This cDNA was used as a probe to study the viral genome expression among the total RNA and the poly (A)-rich RNA extracted from the MF2 and Balb/c embryonic cells. As evidenced by molecular hybridization experiments, the presence of at least one endogenous Balb/c virus in the MF2 virus stocks is suggested. In the productive cells, the viral RNA sequences are expressed in the poly (A)-rich RNA fraction.     

Endothelial cells as antigen-presenting cells: role in human transplant rejection

The immunological properties of human endothelial cells suggest they perform a pivotal role in acute and chronic rejection following solid organ transplantation. In this review the basic features of acute and chronic rejection are described as are the cellular and molecular requirements for antigen presentation. Traditionally, antigen-presenting cells are considered to be bone marrow-derived cells. However, these conclusions have been derived from rodent models of allograft rejection where bone marrow-derived passenger leukocytes are the only source of donor major histocompatibility complex (MHC) class II in the grafted organ. In contrast, in humans, virtually all the microvascular and small vessel endothelial cells are ‘constitutively’ positive for MHC class II antigens. The phenotypic properties of human endothelial cells, their response to cytokines and their ability to stimulate resting T cells are described. Unlike bone marrow-derived antigen presenting cells (APCs), which utilise B7/CD28 interactions, human endothelial cells utilise lymphocyte function antigen 3 (LFA3)/CD2 pathways to stimulate T cells. They activate a CD45RO + B7-independent subpopulation of T cells. Their effect on allogeneic T cells is compared with other non-bone marrow-derived cells such as fibroblasts, epithelial cells and smooth muscle cells, which are unable to stimulate resting T cells. Evidence is presented suggesting that release of MHC and non-human leukocyte antigens (HLA) from endothelial cells stimulates an alloantibody and autoimmune response leading to chronic rejection. Received 30 March 1998; received after revision 4 May 1998; accepted 4 May 1998     

Contractile filaments in cells of regenerating tendon

Summary An extensive cytoplasmic fibrillar system has been observed in fibroblast-like cells of regenerating tendon. It consists of bundles of actin filaments, which often show a cross-striated appearance due to electron dense bodies occurring throughout their length. The functional role of this contractile apparatus seems to be related to the process of movement and orientation of the newly formed cells and to the retraction of the regenerating tendon.Work was supported by grant C. N. R. n. 75.01224.04–115.5479 from Consiglio Nazionale delle Ricerche, Italy.The authors are grateful to Dr G. F. Bottazzo, Dept. Immunology, Middlesex Hospital, London, for carrying out the absorption experiments with purified actin and to Miss M. Rita Nicotra, Miss Laura M. Vassallo and Mr Mario Termine for their technical assistance.     

Photoreactivation of UV damage in culturedDrosophila cells

Summary Cell survival and photoreactivation of 254 nm ultraviolet (UV) light damage in a wild typeDrosophila cell line was assayed by colony formation in liquid medium. F_o, F_q, and extrapolation number for the exponential portion of survival curves are 21 J/m², 3.6 J/m², and 1.5 for non-photoreactivated cells and 110 J/m², 11.2 J/m², and 1.3 for those exposed to photoreactivating light. Maximal photoreactivation occurs at the 100 J/m² region of the curve. At 10 and 50% survival, 75–80% of the UV damage was photoreactivable.     

Mechanisms of ciliogenesis suppression in dividing cells

The primary cilium is a non-motile and microtubule-enriched protrusion ensheathed by plasma membrane. Primary cilia function as mechano/chemosensors and signaling hubs and their disorders predispose to a wide spectrum of human diseases. Most types of cells assemble their primary cilia in response to cellular quiescence, whereas they start to retract the primary cilia upon cell-cycle reentry. The retardation of ciliary resorption process has been shown to delay cell-cycle progression to the S or M phase after cell-cycle reentry. Apart from this conventional concept of ciliary disassembly linked to cell-cycle reentry, recent studies have led to a novel concept, suggesting that cells can suppress primary cilia assembly during cell proliferation. Accumulating evidence has also demonstrated the importance of Aurora-A (a protein originally identified as one of mitotic kinases) not only in ciliary resorption after cell-cycle reentry but also in the suppression of ciliogenesis in proliferating cells, whereas Aurora-A activators are clearly distinct in both phenomena. Here, we summarize the current knowledge of how cycling cells suppress ciliogenesis and compare it with mechanisms underlying ciliary resorption after cell-cycle reentry. We also discuss a reciprocal relationship between primary cilia and cell proliferation.     

Roles of glial cells in synapse development

Brain function relies on communication among neurons via highly specialized contacts, the synapses, and synaptic dysfunction lies at the heart of age-, disease-, and injury-induced defects of the nervous system. For these reasons, the formation—and repair—of synaptic connections is a major focus of neuroscience research. In this review, I summarize recent evidence that synapse development is not a cell-autonomous process and that its distinct phases depend on assistance from the so-called glial cells. The results supporting this view concern synapses in the central nervous system as well as neuromuscular junctions and originate from experimental models ranging from cell cultures to living flies, worms, and mice. Peeking at the future, I will highlight recent technical advances that are likely to revolutionize our views on synapse–glia interactions in the developing, adult and diseased brain.     

Histochemistry of lysosomal enzymes in juxtaglomerular cells

Zusammenfassung In den Granula juxtaglomerulärer granulierter Mäusenierenzellen wurde eine saure Phosphatase und eine-Glykuronidase-Aktivität nachgewiesen. (Methoden für Arylsulphatase und unspezifische Esterase waren negativ.) Es wird der Zusammenhang mit der Lysosomenart der Granula diskutiert.