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Biomedical subjects

L Fiore

Publications and source records attributed to L Fiore.

At least 55 records · Page 3Linked to original sources
PubMed1995

Effect of chloro-, cyano-, and amidino-substituted flavanoids on enterovirus infection in vitro.

Synthetic flavans, isoflavans and isoflavenes substituted with chloro, cyano and amidino groups were tested for their in vitro activity against poliovirus type 2, Coxsackie virus B4, echovirus type 6 and enterovirus 71. Plaque-reduction assays showed that substituted 3-(2H)-isoflavenes, carrying a double bond in the oxygenated ring, possess antiviral activity higher than that of the corresponding isoflavans. The most effective compounds were 4'-chloro-6-cyanoflavan and 6-chloro-4'-cyanoflavan. Studies on the mechanism of action of these two compounds suggested an effect on the early stages of viral replication.

Amidines↗
PubMed1995

p53-dependent and p53-independent activation of apoptosis in mammary epithelial cells reveals a survival function of EGF and insulin.

The p53 tumor suppressor protein has been implicated as a mediator of programmed cell death (PCD). A series of nontransformed mammary epithelial cell (MEC) lines were used to correlate p53 function with activation of PCD. Treatment of MECs expressing mutant, inactive, or no p53 with DNA-damaging agents did not induce apoptosis. Upon introduction of temperature-sensitive p53 into HC11 cells, which lack wild-type (wt) p53, PCD was observed after mitomycin treatment at 32 degrees, when the ts p53 protein is in wt conformation. Thus, wt p53 mediates activation of PCD in response to mitomycin in HC11 cells. Treatment of the MCF10-A cells, which express wt p53, with various DNA-damaging agents led to nuclear accumulation of p53. Only mitomycin treatment led to an increase in the number of apoptotic nuclei. ErbB-2-transformed MCF10-A cells responded to mitomycin, cisplatin, and 5-Fl-uracil, suggesting that signaling from activated ErbB-2 enhances the cells ability to respond to DNA damage. A combination of high cell density and serum-free medium induces apoptosis in all MECs tested, irrespective of their p53 status. Under these conditions, EGF or insulin act as survival factors in preventing PCD. These data might elucidate some aspects of breast involution and tumorigenesis.

Animals↗
PubMed1995

Antigenicity, immunogenicity and passive protection induced by immunization of mice with baculovirus-expressed VP7 protein from rhesus rotavirus.

The major neutralization antigen VP7 of rhesus rotavirus (RRV) was expressed in a baculovirus recombinant system. The expressed VP7 showed the same molecular mass as native VP7, and was recognized by hyperimmune sera as well as neutralizing and non-neutralizing monoclonal antibodies (MAbs) raised against RRV. Intraperitoneal administration of the expressed VP7 in mice elicited the production of serum antibodies which were able to immunoprecipitate VP7 from RRV-infected cell lysates and to neutralize the virus in vitro. Sera from immunized mice competed for binding to RRV in an ELISA with both neutralizing and non-neutralizing MAbs specific for VP7. Using a passive protection model of rotavirus disease, vaccination of mice with the recombinant VP7 induced partial protection from infection. These results suggest that the baculovirus-expressed VP7 may be useful in priming a protective immune response to rotavirus infection.

Animals↗
PubMed1995

Adrenocorticotropin release is not involved in the nicotine-induced reversal of hemorrhagic shock in anesthetized rats.

In a model of volume-controlled hemorrhagic shock causing the death of all control animals within 30 min, the intravenous injection of nicotine produced a rapid, sustained and dose-dependent restoration of cardiovascular and respiratory functions, with 60 and 100% survival 2 h after the administration of 3 and 12 micrograms/kg, respectively. An effect similar to that of the highest dose of nicotine were obtained with the intravenous bolus injection of ACTH(1-24) at the dose of 160 micrograms/kg. However, the ACTH plasma levels of hemorrhage-shocked rats treated with nicotine was not different from that of hemorrhage-shocked rats treated with saline, thus excluding the possibility that nicotine-induced shock reversal may be due to the massive release of ACTH. Since in rats pretreated with cycloheximide at a dose (20 mg/kg intraperitoneally) causing an 82% inhibition of protein synthesis, and then bled to hemorrhagic shock, the effect of nicotine was greatly reduced (only the dose of 50 micrograms/kg producing 100% survival 2 h after treatment), protein synthesis, however, seems to be important for the effect of nicotine in hemorrhagic shock, at least at the lowest doses.

Adrenocorticotropic Hormone↗
PubMed1994

Induction of multidrug resistance (MDR) by transfection of MCF-10A cell line with c-Ha-ras and c-erbB-2 oncogenes.

To investigate the relationship between oncogene activation and appearance of multidrug resistance (MDR) we transfected the human breast epithelial cell line MCF-10A, negative for the expression of the P-glycoprotein, with c-Ha-ras and/or c-erbB-2 oncogenes. The appearance of the MDR phenotype was then studied by evaluating mdr-1 mRNA expression, the presence of P-glycoprotein on the cell membrane and the onset of doxorubicin resistance, together with the effect of the reversing agent verapamil. We found that only MCF-10A transfected with both c-Ha-ras and c-erbB-2 oncogenes acquired the MDR phenotype.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Response of normal and oncogene-transformed human mammary epithelial cells to transforming growth factor beta 1 (TGF-beta 1): lack of growth-inhibitory effect on cells expressing the simian virus 40 large-T antigen.

The relationship between the expression of selected oncogenes having different modes of action and the loss of the capacity to respond in vitro to transforming growth factor-beta I (TGF-beta I) was analyzed in human mammary epithelial cells (MEC). Primary MEC cultures from healthy donors and the spontaneously immortalized MCF-10A cell line were used as normal controls. Various assays (employing both complete and chemically defined media) were used: short-term DNA synthesis, long-term cell proliferation under anchorage-dependent and -independent conditions, expression of surface-differentiation molecules. Whereas primary MEC and the MCF-10A cell line were fully responsive to the growth-inhibitory activity of TGF-beta I under different test conditions, MEC transformed by c-Ha-ras, c-erbB2, int-2, or SV40-large-T antigen were not inhibited by TGF-beta I in a short-term DNA-synthesis assay. However, in anchorage-dependent conditions TGF-beta I inhibited the proliferation of all lines investigated, with the exception of SV40-T-antigen-transformed MEC. The colony-formation assay in soft agar revealed that all lines, but not those expressing the int-2 or the SV40-T-antigen genes, were inhibited by TGF-beta I. Neutralizing antibody to TGF-beta had no significant effects on oncogene-transformed lines, suggesting that the endogenous production of an active form of this growth factor is not a major determinant in MEC transformation by the oncogenes investigated. The only observed effect of TGF-beta I on selected surface-differentiation molecules was that normal MEC produced increased levels of the human milk fat globule antigen-I. Thus it appears that the response of MEC to TGF-beta I is consistently attenuated by the insertion of a variety of oncogenes and that it is abolished only by the expression of the SV40-large-T antigen. Whereas no single in vitro assay was capable of accurately reflecting the actual responsiveness of different lines, the growth-curve assay in anchorage-dependent conditions was the best single predictive test.

Antigens, Surface↗
PubMed1993

Normal breast epithelial cells produce interleukins 6 and 8 together with tumor-necrosis factor: defective IL6 expression in mammary carcinoma.

Virtually pure primary cultures of normal mammary epithelial cells (MEC) obtained from healthy women were shown to release interleukin 6 and 8 (IL6, IL8) and to produce a nonsecreted form of tumor-necrosis factor (TNF). No interferon (IFN), whether alpha, beta, or gamma, or IL1-alpha or -beta could be detected. Analysis of cellular RNA confirmed these findings and showed that MEC also express IL6 receptor and TNF-alpha-related mRNAs. Epithelial cells were selectively stained by antibodies to IL6, IL8 and TNF-alpha both in primary cultures and in the normal mammary gland. Samples of human milk contained sizable amounts of IL6, IL8 and IFN-gamma; yet the liquid phase was consistently negative for other cytokines (i.e., TNF-alpha, IFN-alpha/-beta, IL1-alpha/-beta). Expression of IL6 (but not of IL8 and TNF-alpha) was abolished in ductal infiltrating carcinomas and greatly reduced in cultures of oncogene-transfected mammary cells, suggesting that alterations of IL6 expression are associated with pathogenesis in breast cancer.

Adolescent↗
PubMed1993

Growth-stimulating activity of interleukin 6 on human mammary epithelial cells transfected with the int-2 gene.

We have shown recently that normal human mammary epithelial cells do produce interleukin 6 (IL6), interleukin 8, and a nonsecreted form of tumor necrosis factor. Here we report that ductal infiltrating mammary carcinomas fail to express immunoreactive IL6. Since abnormalities of cytokine genes are a frequent event in cancer, we investigated the production of and the response to cytokines of mammary cells using a panel of oncogene-transformed cells derived from the spontaneously immortalized MCF-10A cell line. We found that only the parental line and the int-2-transformed cells responded to exogenous IL6 and/or were suppressed by IL6-neutralizing antibody. In contrast to highly transformed cells, these two lines, which were either nontransformed (MCF-10A) or weakly transformed (int-2), were found to express IL6 receptors. These data suggest that loss of IL6 pathways can be a marker of mammary cell transformation.

Animals↗
PubMed1992

Regulation of surface-differentiation molecules by epidermal growth factor, transforming growth factor alpha, and hydrocortisone in human mammary epithelial cells transformed by an activated c-Ha-ras proto-oncogene.

Spontaneously immortalized human mammary epithelial cells MCF-10A were transfected with an activated c-Ha-ras oncogene. Transfected cells (MCF-10T) acquire a malignant phenotype, as already reported. Studies of 125I-2'-deoxyuridine incorporation in cultures given graded doses of hydrocortisone (HC), cholera toxin (CT), epidermal growth factor (EGF), and transforming growth factor alpha (TGF-alpha) showed that though MCF-10T had become almost independent on exogenous EGF and TGF-alpha, they continued to respond to the synergistic effect of HC and CT plus EGF. Both lines were phenotypically characterized with an immunoradiometric assay in live cells. Expression of MHC class-I molecules, human milk-fat-globule-I antigen, and EGF receptor was reduced in ras-transfected cells, although other differentiation markers were unchanged. Exogenous EGF down-regulated the expression of functional EGF-R, selectively in transformed cells. TGF-alpha failed to modulate EGF-R. In contrast, HC strongly stimulated the expression of EGF-R while depressing MHC class-I molecules. Thus, it appears that in vivo HC may co-operate with TGF-alpha and EGF in promoting the growth of transformed mammary cells. This hormone might also favor the escape from immune surveillance by reducing the expression of surface differentiation markers.

Antigens, Differentiation↗
PubMed1992

Humoral immune responses to VP4 and its cleavage products VP5* and VP8* in infants vaccinated with rhesus rotavirus.

The humoral immune response to rhesus rotavirus (RRV) VP4 and its cleavage products VP5* and VP8* was determined in paired serum samples from 44 infants vaccinated with RRV or human rotavirus-RRV reassortants and 5 placebo recipients. Our aim was to try to measure the response to those regions of VP4 most closely related to protection. An enzyme-linked immunosorbent assay (ELISA) was used to measure the immunoglobulin G immune response to baculovirus-expressed full-length RRV VP4, full-length VP8*, and the amino-terminal polypeptide of VP5* called VP5*(1) (amino acids 248 to 474). The two antigenic regions of VP4 selected for study, VP5*(1) and VP8*, have previously been shown to contain most of the cross-reactive and strain-specific neutralization epitopes, respectively, while the remaining carboxy-terminal half of VP5* (amino acids 475 to 776) has not been clearly associated with neutralization. All three recombinant proteins were antigenically conserved, since they reacted with a library of neutralizing monoclonal antibodies directed at VP4. There was a high percentage of seroresponders to VP4 (61%) or to VP8* (52%), but fewer infants seroresponded to VP5*(1) (11%). In addition, infants responding to VP5*(1) had considerably lower titers than to VP4 or VP8*. Immune response to VP4 correlated strongly with the responses detected by the plaque reduction neutralization assay but did not correlate with the responses detected by the ELISA to whole RRV. These data imply that the VP5*(1) region is less immunogenic than the VP8* region of VP4 in infants immunized with RRV or RRV reassortants. The low immunogenicity of VP5* might adversely affect the efficacy of RRV vaccine candidates.

Animals↗
PubMed1992

Bidirectional transmission in the cerebrobuccal connective of Aplysia during feeding.

The neuronal activity of the cerebrobuccal connective (CBC) of Aplysia was recorded, using 2 implanted electrodes, under three conditions; 1) in the absence of feeding behaviour, 2) during appetitive feeding behaviour and 3) during consummatory feeding behaviour. Cross-correlation analysis of the recordings was then performed to subdivide spikes on the basis of their direction and speed of propagation. This revealed differences in the neuronal activity during the 3 conditions. There was little activity in the CBC when animals were not feeding. During appetitive and consummatory feeding behaviour the activity in the CBC increased. Units travelling in each direction were present, but with differential activity during the 2 behavioural patterns.

Animals↗
PubMed1992

Trophic action of acetyl-L-carnitine in neuronal cultures.

Daily addition of acetyl-L-carnitine (100 microM) to cultured cerebellar granule cells since the first day of maturation led to an increased rate of expression of D-[3H]aspartate uptake (an established marker of maturation of glutamatergic neurons) and of N-methyl-D-aspartate (NMDA) receptors linked to large conductance ion channels permeable to Ca2+. Acetyl-L-carnitine treatment also increased neuronal survival, as reflected by a greater percentage of cultures retaining functional NMDA receptors after 15 days of maturation. These results support the view that acetyl-L-carnitine exerts neuronotrophic activity and prevents age-dependent neuronal degeneration.

Acetylcarnitine↗
PubMed1991

Estrogen modulates stimulation of inositol phospholipid hydrolysis by norepinephrine in rat brain slices.

The influence of estrogen on stimulation of inositol phospholipid hydrolysis by norepinephrine and carbamylcholine has been studied by measuring the accumulation of [3H]inositol-monophosphate ([3H]InsP) in cortical, hippocampal and striatal slices from ovariectomized rats. Repeated (but not a single) subcutaneous injections of estradiol benzoate (EB) (2 micrograms/animal once every 2 days for 10 days) markedly reduced stimulation of inositol phospholipid hydrolysis by norepinephrine in hippocampus and corpus striatum. Conversely, the efficacy of norepinephrine was increased in cortical slices. Estrogen treatment did not affect basal or carbamylcholine-stimulated [3H]InsP formation. In vitro addition of 17 beta-estradiol (1-100 nM) failed to modify norepinephrine- or carbamylcholine-induced [3H]InsP production in all regions examined. An increased density of alpha 1-adrenergic binding sites in cortical membranes paralleled the enhanced responsiveness of inositol phospholipid hydrolysis to norepinephrine induced by EB treatment in this area, whereas no significant changes in [3H]prazosin binding were found in membranes from hippocampus and corpus striatum. These results indicate that estrogen may affect inositol phospholipid hydrolysis in discrete brain areas, suggesting a complex role for estradiol in modulating noradrenergic receptor activity in the central nervous system.

Animals↗