Dimeric chromenes and mixed dimers of a chromene with euparin from Encelia canescens

The investigation of Encelia canescens afforded, in addition to several known compounds, four new dimeric p-hydroxyacetophenone derivatives, two epimeric chromene dimers and two epimeric mixed dimers of euparin and encecalin. Furthermore, derivatives of tremetone and of encecalin were present. The structures were elucidated hy high field ¹H NMR spectroscopy.     

Immunoperoxidase localization of fibronectin during odontoblast differentiation. An ultrastructural study

Immunoperoxidase labeling of fibronectin in one-day-old mouse first lower molars allowed to visualize a striking redistribution of this glycoprotein during terminal cytodifferentiation of odontoblasts. The modifications involved both extracellular and cell surface localizations. The possible roles of these modifications in terminal differentiation of odontoblasts are discussed.     

Developmental expression of 44-kDa bone phosphoprotein (osteopontin) and bone γ-carboxyglutamic acid (Gla)-containing protein (osteocalcin) in calcifying tissues of rat

New aspects of the distribution and developmental appearance of the 44-kDa bone phosphoprotein (44K BPP, also called sialoprotein I or osteopontin) and bone gamma-carboxyglutamic acid (Gla)-containing protein (BGP, also called osteocalcin) during osteogenesis and dentinogenesis were investigated with immunocytochemical techniques using monospecific, affinity-purified polyclonal antibodies. Sections from newborn rat incisors and from various bone anlagen of newborn animals and fetuses were processed for detection of 44K BPP or BGP antigenicity. In addition, histochemical reactions for detection of alkaline phosphatase or calcium salts were performed on a number of the sections. The 44K BPP appears to be synthesized and secreted by chondrocytes only in the areas of cartilage-to-bone transition; these cells could participate indirectly in the process of bone formation by providing a suitable scaffold onto which primary marrow osteoblasts attach and spread. During osteogenesis, 44K BPP is found in bone-forming cells almost concomitantly with the appearance of alkaline phosphatase and before osteoid deposition, whereas BGP is still absent during early stages of mineralization. We hypothesize that this dramatic difference between the developmental appearance of 44K BPP and BGP reflects the delayed expression of the BGP gene relative to that of 44K BPP. In long-term cultures of bone marrow from adult mice, some fibroblastic cells expressed the 44K BPP phenotype; these cells could represent early osteogenic progenitor cells. Some experiments also suggested that, as with BGP, 44K BPP or an immunologically related protein is synthesized by some odontoblasts and secreted into predentin, prior to the onset of mineralization.     

Lipid detection by malachite green-aldehyde in the dental basement membrane in the rat incisor

Summary Developing rat incisors were treated with malachite green-aldehyde fixative solution (MGA), which retains and stains lipids. We observed positive staining occurring as dots in the basement membrane. Most of these dots (2–3.5 nm in diameter) were grouped in the lamina densa but some were also present in the lamina lucida and the lamina fibroreticularis. These data provide evidence for the existence of lipids in the dental basement membrane and suggest that they are distributed together with the various groups of proteins so far detected.     

Epithelial-mesenchymal interactions: effects of a dental biomatrix on odontoblasts

The functional differentiation of odontoblasts requires specific interactions between these cells and the extracellular matrix. To further analyze these phenomena we studied the effects of a "dental papillae biomatrix" on isolated dental papillae cultured in vitro. The dental papillae biomatrix was extracted from EDTA-dissociated day-18 mouse dental papillae by homogenization, NaCl and enzymatic treatments, and deposited on Millipore filters. This biomatrix was studied by means of transmission electron microscopy and indirect immunofluorescence: it contained collagen fibrils, type IV collagen, fibronectin and laminin; cellular residues were also observed. The dental papillae were isolated by trypsin treatment of homologous tooth germs and cultured on uncoated (control) and coated filters. As shown by histological and cytological data, odontoblast-like cells never differentiated in control cultures. In presence of biomatrix and serum, polarized functional cells were observed. The functional state of these cells was enhanced by the addition of ascorbic acid to the culture media. Study of the incorporation of 3H-proline in cultured dental papillae and in macromolecules secreted into the culture media corroborated the morphological findings.     

Sarcolemmal Na+-Ca2+ exchange during the development of genetically determined cardiomyopathy

The UM-X7.1 myopathic and control hamsters at 40, 120 and 280 days of age were employed for the examination of heart sarcolemmal Ca2+-transport activities. Na+-dependent Ca2+ uptake activities were significantly depressed in myopathic animals at 120 and 280 days of age in comparison to the control values. No difference in Na+-induced Ca2+ release activities was found between control and experimental sarcolemmal vesicles. ATP-dependent Ca2+ binding and Ca2+-stimulated, Mg2+ ATPase activities were depressed in the experimental animals at 120 and 280 days of age. Similar alterations in the sarcolemmal Na+-dependent Ca2+ exchange and Ca2+-pump activities were seen upon treating the control hamsters with 40 mg/kg isoproterenol for 24 hr. It is suggested that a depression in the sarcolemmal Ca2+ transport activities may contribute to the development of intracellular Ca2+ overload in the genetically determined cardiomyopathy in hamsters and such a defect may be due to excessive amount circulating catecholamines in these animals.     

Further glaucolides from south african Vernonia species

The investigation of three South African Vernonia species afforded minute amounts of five new glaucolides, two monoepoxides and three diepoxides. The structures were elucidated by ¹H NMR spectroscopy. The roots of Vernonia sutherlandii contain, in addition to vernonataloide, bergamotene and santalene, minute amounts of the corresponding acetoxy derivatives.     

Correlation between structure of polyoxotungstates and their inhibitory activity on polymerases

The 21-tungsto-9-antimonate (TA, HPA 23), a polyoxotungstate, has shown a significant antiviral activity in vivo and in vitro. It inhibits viral and bacterial DNA polymerases. In this paper, several compounds of two polyoxotungstic families, tungstoantimonates and tungstoarsenates, have been used to specify the mechanism of polymerase inhibition. It has been demonstrated that the inhibitory activity of polyoxotungstates is not related to the occupation of their coordinative sites by cations, nor to the nature of these bound cations. Kinetic studies and binding assays have shown that polyoxotungstates bind to the polymerases in competition with the nucleic acid template. This result seems to be related to their polyanionic nature. Furthermore, the size and charge of these compounds may play a prominent part in their affinity for the polymerases.     

Bone Marrow Graft in Man after Conditioning by Antilymphocytic Serum

Allogeneic bone marrow grafts carried out after previous administration of antilymphocytic serum alone were attempted in 16 patients. Of these, six had acute myeloblastic leukaemia, four acute lymphoblastic leukaemia, and one a blast cell crisis in polycythaemia vera. Ten of these patients were in an overt phase of the disease and resistant to chemotherapy, while nine had complete agranulocytosis. In five of these patients erythrocyte and leucocyte antigenic markers demonstrated the establishment of the graft. One patient had thalassaemia major, and four others had aplasia of the bone marrow, in one case due to chloramphenicol poisoning and in another to virus hepatitis. The grafts were successful in the last two patients and transformed their clinical condition.No signs of early acute secondary disease were noted in any of the patients, either when the donor had been given antilymphocytic serum or when he was untreated. The grafts had no adoptive immunotherapeutic effect on the acute leukaemia. These observations have clearly shown that antilymphocytic serum has an immunosuppressive effect in man when it is used alone.