Search PubMed⌕ Search

Biomedical subjects

L Lombardi

Publications and source records attributed to L Lombardi.

At least 127 records · Page 7Linked to original sources
PubMed1975

In vitro production of lymphocyte and granulocyte proliferation inhibitors (chalones?) from living cells.

Media conditioned with viable rat and calf spleen lymphocytes were seen to be able to inhibit 3H-thymidine uptake by rat thymocytes and the mitogenic response of human lymphocytes to PHA but not bone marrow cells proliferation. The inhibitor appeared to have a molecular weight greater than 50,000 daltons, as determined by Amicon Diaflo ultrafiltration. Media conditioned with rat granulocytes had a similar tissue specific but species non-specific inhibitory action. Also human leukemic cells appeared able to produce in vitro an inhibitor of cell proliferation when a certain degree of differentiation was present.

Animals↗
PubMedDate not supplied

The influence of in vivo pretreatment of cyclophosphamide on phagocytic activity of mouse macrophages in vitro.

The action of cyclophosphamide on phagocytosis by macrophages from mouse peritoneal exudate cultured in vitro was studied. The mice were pretreated with cyclophosphamide administered for seven days. The experiments were carried out in the presence of serum (with or without complement) from untreated animals or without serum. A significantly increased phagocytic activity was shown in experiments without serum and when decomplemented serum was used. No significant variation was found when macrophages from treated mice were tested with serum with complement from untreated animals. It is tentatively assumed that low dosage administration in vivo of cyclophosphamide does not affect macrophage phagocytic activity while several findings suggest an inhibitory effect of cyclophosphamide on T and B lymphocytes.

Animals↗
PubMedDate not supplied

Development of a multigenic plasmid vector for HCV DNA immunization.

HCV viral nucleocapsid protein (C), non-structural protein 3 (NS3) and the envelope glycoproteins E1 and E2 are candidate immune targets for developing anti-HCV DNA vaccine. Nevertheless, the immune response elicited by these antigens often appears weak and/or transient. Different approaches have been studied for enhancing and/or modulating the immune response of the DNA vaccine. On the basis of a prototype multigenic plasmid vector constituted of two different transcription cassettes (pRC100), we have developed a plasmid vector that allows the independent and simultaneous expression of murine IL2 and of an antigenic domain of the HCV NS3 C terminus (pRC112-HCV). The highly conserved NS3 region spans from nt 4403 to nt 4829 and contains two putative B and T epitopes. The development of this multigenic plasmid vector may combine the expression and local production of an immunomodulatory molecule (mIL2) together with the possibility of addressing the host immune response to the most immunogenic and conserved epitopes, specifically tailored in the plasmid vector.

Animals↗
PubMedDate not supplied

Influence of dopamine on cyclic nucleotide enzymes in bovine retinal membrane fractions.

Dopamine is a major neurotransmitter and neuromodulator in vertebrate retina. Although its pharmacological and physiological actions are well understood, the biochemical mechanisms of its signal transduction are less clear. Acting via D1 receptors, dopamine was shown to increase cyclic AMP levels in intact retina and to activate adenylate cyclase in retinal homogenates. The action via activation of D2 receptors is controversial: it was reported to decrease cyclic AMP levels in intact retina but inhibition of cyclase could not be demonstrated in retinal homogenates; also it was reported to activate rod outer segment cyclic GMP phosphodiesterase in vitro but did not decrease cyclic GMP levels in aspartate-treated retinas. We made an attempt to fractionate bovine retinal membranes and to investigate the effects of dopamine, via D1 and D2 receptors, on the synthesis and hydrolysis of cyclic AMP and cyclic GMP. Activation of cyclic AMP synthesis was noted in all fractions, but no effects were evident on cyclic nucleotide hydrolysis or cyclic GMP synthesis in any fraction. Also, D2 agonist did not inhibit cyclic AMP synthesis. These observations suggest that D2 receptors may not be directly coupled to cyclic nucleotide metabolizing enzymes in bovine retina.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMedDate not supplied

Phagocytosis of hemozoin (native and synthetic malaria pigment), and Plasmodium falciparum intraerythrocyte-stage parasites by human and mouse phagocytes.

Hemozoin, the detoxification product of hemoglobin heme, piles up as electron-dense material in the food vacuole (FV) of intraerythrocytic malaria parasites (malaria pigment). In infected individuals, pigment is internalized by both circulating and resident phagocytes, thus modulating their functions. Synthetic beta-hematin, prepared in vitro from hematin (ferriprotoporphyrin IX hydroxide) in acidic condition, is spectroscopically identical to hemozoin. In this electron microscopy study, native and synthetic hemozoin also prove to be morphologically indistinguishable (large polygonal crystals with apparent transverse banding) and to undergo the same process when internalized by phagocytes (primarily a direct uptake of crystals, similar to what is described for asbestos fibers). On the contrary, whole parasites appear to follow a classical endocytic pathway. This suggests that there may be differences between the ingestion of free particles and whole parasites in terms of modulation of phagocytes' functions.

Animals↗
PubMedDate not supplied

The ultrastructure of malignant fibrous histiocytoma (case report).

A soft tissue malignant fibrous histiocytoma was studied by light and electron microscopy. The presence of fibroblast-like cells, histiocyte-like cells, undifferentiated stem cells, and xanthomatous cells was confirmed. Fibroblast- and histiocyte-like multinucleated giant cells were also observed. The observation of lysosomes in some fibroblast-like cells, the features of undifferentiated stem cells, and the presence of cells and intermediate characteristics common to xanthomatous, histiocytic, and stem cells suggest a strict relationship among these cellular types.

Adolescent↗
PubMedDate not supplied

The aid of electron microscopy in the diagnosis of osteosarcoma of the bone (case report).

Osteogenic sarcoma with marked cellular anaplasia and little or no osteoid formation may present major problems in histologic identification. The application of electron microscopy is demonstrated in a case of a poorly differentiated osteosarcoma of the tibia. Unequivocal electron microscopic diagnostic findings are described in relation to light microscopic data.

Adolescent↗
PubMedDate not supplied

Production of a monoclonal antibody directed against the high-affinity nerve growth factor receptor.

The high-affinity nerve growth factor receptor corresponds to the tyrosine protein kinase encoded by the proto-oncogene trkA. Different findings suggest that nerve growth factor (NGF) can be operative in the growth modulation of tumor cell lines possessing high-affinity binding sites for this molecule. Using as immunizing material the SKNBE neuroblastoma cell line transfected with proto-trkA we produced a monoclonal antibody (MAb) able to recognize the high-affinity nerve growth factor receptor. The selected MAb, designated MGR12, is directed against an epitope present on the extracellular domain of the receptor since it showed reactivity on living trkA-expressing cells and was able to immunoprecipitate the proto-trkA molecule. The MGR12 MAb is directed against a non-functional epitope since it neither inhibited NGF binding nor induced receptor internalization. This new reagent appears to be an appropriate tool for analyzing the expression of high-affinity nerve growth factor receptor in tumors of different origin and for elucidating its involvement in tumor progression.

3T3 Cells↗
PubMedDate not supplied

The use of fixed-frozen tissue in routine ultrastructural evaluation and immunogold labeling.

A method of freezing fixed surgical tissue specimens for long-term storage and subsequent resin embedding was developed. The method entails fixation of the specimens in Karnowsky's liquid, cryoprotecting with 10% sucrose, freezing in melting Freon gas, and storage at -80 degrees C. When needed, even after years, the frozen tissue pieces are thawed in lukewarm (37 degrees C) buffer and embedded in resin (Epon or Lowicryl). Ultrastructural detail as well as immunocytochemical reactivity of a wide variety of cellular constituents are well preserved. The method is practical and allows retrospective embedding in Lowicryl resin (a technique not easily applicable in everyday routine) for subsequent ultrastructural immunolocalization studies.

Acrylic Resins↗
PubMedDate not supplied

Ultrastructural characterization of poorly differentiated rhabdomyosarcomas.

Twenty-five rhabdomyosarcomas, histopathologically and immunocytochemically classified as embryonal (12 cases), alveolar (11 cases), and pleomorphic (two cases), were studied by routine and immunogold electron microscopy, to identify, in poorly differentiated cells, reproducible markers useful for diagnostic purposes. Rhabdomyoblasts with rudimentary sarcomeres were observed in 12 cases (48%). Large cells (named oval cells) with an oval shape and an eccentric nucleus, like rhabdomyoblasts but lacking organized myofilaments, were observed in 20 cases (80%). By immunogold electron microscopy, performed on four of 25 cases, both oval cells and rhabdomyoblasts showed abundant intermediate filaments positive for desmin. Oval cells may be used as markers of poorly differentiated rhabdomyosarcomas.

Adolescent↗