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Biomedical subjects

M Del Monte

Publications and source records attributed to M Del Monte.

8 recordsLinked to original sources
PubMed1991

Extracellular matrix mediated growth and differentiation in human pigment epithelial cell line 0041.

Efforts to grow differentiated pigment epithelial cells have led to a characterization of the growth kinetics of spontaneously established, continuously growing, human retinal pigment epithelial (PE) cell line 0041 on several biomatrices. These substrates were prepared from (a) placental and amniotic membrane, (b) commercially available basement membrane matrix (Matrigel), (c) dishes coated with extracellular matrix secreted by endothelial cells (ECM), (d) dishes coated with collagen IV and/or laminin, (e) dishes coated with collagen I and/or fibronectin. Our findings suggest that tissue culture plastic and dishes coated with collagen IV alone promote higher cell densities, while highest plating efficiency (24 hrs) was seen on tissue culture plastic and Matrigel. The highest degree of differentiation (epithelioid appearance, apical villi and junctional complexes) was seen in cells plated on dishes coated with collagen IV and extracellular matrix secreted by endothelial cells. Cells were epithelioid and polarized on those two substrates; they expressed fine finger-shaped villi and the highest degree of cell contact (in the form of junctions). Cells grown on Matrigel looked like fibroblasts and became deeply pigmented; however, the nature of the pigment remains to be determined. Collagen IV and ECM coated dishes, therefore, are most suitable for cultures of human PE cell line 0041 because they provide higher cell densities while retaining the differentiated state. This is the first report where an established pigmented epithelial cell line has been induced to become differentiated by use of extracellular matrices and extracellular matrix components.

Adolescent↗
PubMed1990

Ganglion-blocking agents enhance neurally mediated bronchoconstriction in the guinea-pig: possible role of sensory neuropeptides.

The effect of ganglion blockade by hexamethonium bromide (0.1-100 mumol.kg-1) and pentolinium tartrate (0.01-3 mumol.kg-1) on the bronchoconstriction induced by vagal nerve stimulation (15 Hz, 0.2 ms, 3 s, 7-20 V) was evaluated in the anaesthetized guinea-pig. Both ganglion-blocking agents potentiated this response dose dependently. When the neural bronchoconstriction was suppressed by atropine, hexamethonium restored this response dose dependently. Hexamethonium produced inhibitory effects on vagally induced bronchoconstriction in capsaicin-desensitized and in propranolol- or reserpine-pretreated guinea-pigs. Propranolol (0.03-3 mumol.kg-1) produced a marked dose-dependent increase of neural bronchoconstriction (which was markedly reduced, about 10 times) in capsaicin-desensitized animals. Our results show that ganglion-blocking agents potentiate neural bronchoconstriction in the guinea-pig and that sensory neuropeptides may have a role in this effect. Moreover, beta-adrenergic modulation of the release of neuropeptides from vagal sensory fibers is suggested.

Anesthesia↗
PubMed1990

Mechanism of the potentiation of neurally-induced bronchoconstriction by gallamine in the guinea-pig.

1. Electrical stimulation of the cervical vagi (15 Hz, 0.2 ms, 3 s, 7-15 V) produced a slight bronchoconstriction in the anaesthetized guinea-pig. This effect was fully abolished by atropine, while gallamine (0.1-10 mumol kg-1) produced a dose-dependent increase up to ten fold. 2. Gallamine-induced potentiation of neurally-mediated bronchoconstriction was not inhibited by depletion of sensory neuropeptides with capsaicin or by pretreatment with pyrilamine. In propranolol-pretreated guinea-pigs the potentiation induced by gallamine 3 and 10 mumol kg-1 was inhibited by 40 and 46%, respectively. 3. Physostigmine (0.5 mg kg-1) produced a very slight and slowly developing bronchoconstriction in the anaesthetized guinea-pig, which was also potentiated dose-dependently by gallamine (0.1-10 mumol kg-1). 4. Gallamine (10 mumol kg-1) potentiated the bronchial anaphylactic response induced by aerosol challenge with ovalbumin in actively sensitized guinea-pigs. 5. These results suggest that neither sensory neuropeptides nor histamine are involved in the gallamine-induced potentiation of neurally-mediated bronchoconstriction, while inhibition of the sympathetic nervous system may play a minor role. They are in general agreement with the hypothesis that gallamine antagonizes acetylcholine selectively at prejunctional muscarinic receptors in the guinea-pig airways, thus increasing its release from parasympathetic nerve terminals. These autoreceptors appear to be operant during anaphylactic bronchoconstriction.

Acetylcholine↗
PubMed1990

Establishment of human retinal pigment epithelial cell lines by oncogenes.

The primary human retinal pigment epithelial cells were transfected with oncogenic sequences derived from viruses and cellular homologues of retroviral oncogenes 'protooncogenes' linked to simian virus 40 (SV-40) and retroviral promoters. Foci of cells were noted between 2 to 4 weeks after transfection. Individual colonies of cells were expanded from cultures transfected with SV-40 virion DNA, SV-40 large T antigen gene, Ha-ras oncogene, human and mouse c-myc and adenovirus E1A gene. Established cell lines tested were positive for the specific oncogene sequences by Southern hybridization and also expressed the protein as assayed by immunofluorescence and immunoblot analysis. Cell lines established with SV-40 large T antigen, and SV-40 virion DNA, exhibited epithelioid morphology up to the 25th passage and later became more rounded. However, all cell lines established with other oncogenes continued to retain epithelial morphology. Functional analysis of the cell lines demonstrated the presence of polarity and the ability to phagocytize rod outer segments, characteristics of retinal pigment epithelial cells. The use of oncogenes with immortalization/transformation potential may allow the establishment of cell lines from ocular tissues for analysing the biochemical basis of a disease like retinitis pigmentosa.

Antigens, Polyomavirus Transforming↗
PubMed1989

In vitro phenotypic and functional characterization of human pigment epithelial cell lines.

We have characterized human retinal pigment epithelium (HRPE) for the expression of cell surface antigens. Primary HRPE cultures, established cell lines, and freshly brushed pigment epithelial cells all express HLA-ABC but not HLA-DR antigens. However, both primary cultures and established cell lines can be induced by gamma interferon stimulation to express HLA-DR in a dose dependent manner. Only freshly brushed HRPE cells express Fc, and no cells demonstrated the presence of C3b. Our results show that HRPE cells change in culture, as reflected by the loss of Fc receptors, but retain the ability to synthesize HLA-ABC spontaneously and HLA-DR upon stimulation.

Adolescent↗
PubMedDate not supplied

Octylonium bromide, an antagonist of platelet-activating factor.

Octylonium bromide, a spasmolytic agent in clinical use for the treatment of increased tone and/or motility of the gastrointestinal tract, was examined for its ability to antagonize some biological actions of platelet-activating factor. It was found capable of inhibiting, in a concentration- or dose-dependent fashion, the platelet-activating factor-induced platelet aggregation of rabbit platelet-rich plasma, bronchoconstriction in guinea-pigs, hypotension in rats and lethality in mice, its potency being between 1/15 and 1/50 that of WEB 2086. On the other hand, octylonium bromide was not capable of inhibiting the platelet-activating factor-induced contraction of guinea-pig lung parenchymal strips, an effect which is inhibited by WEB 2086 only at high concentrations. It is worth mentioning that octylonium bromide antagonized endotoxin-induced gastrointestinal damage, known to be due to platelet-activating factor release, at doses comparable to those which exert a spasmolytic effect in man. The role of platelet-activating factor in human gastrointestinal disorders has not yet been clearly established and, therefore, the clinical implications of this property of octylonium bromide are at the moment unknown.

Animals↗