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S Grimaldi

Publications and source records attributed to S Grimaldi.

54 records · Page 3Linked to original sources
PubMed1982

Effects of thyroxine binding on the stability, conformation, and fluorescence properties of thyroxine-binding globulin.

The effects of thyroxine (T4) on several molecular properties of human thyroxine-binding globulin (TBG) have been evaluated. Changes in the sedimentation constant and relaxation time indicate that TBG becomes more symmetric and compact when T4 is bound. This modification in structure is associated with an increase in the stability of TBG to denaturation by either acid or guanidinium chloride. T4 binding also produces changes in the emission and excitation spectra of TBG, reflecting different environments of the four tryptophanyl residues. T4 preferentially quenches residues in a less polar environment. In addition, it alters the effect of the collisional quencher, acrylamide, so as to indicate a shift in the environment of some of the exposed tryptophanyl residues.

Acrylamides↗
PubMed1982

Effect of thyroxine on molecular properties of native and dansylated thyroxine-binding globulin.

The effect of thyroxine (T4) on the stability of thyroxine-binding globulin (TBG) was investigated by examining intrinsic (tryptophan) or extrinsic (DNS) fluorescence as structural probes to demonstrate the presence of an induced conformation change. A thermal transition was observed at 55 degrees C for TBG by Trp fluorescence, which is evidence for heat denaturation, whereas no transition was observed in the same temperature range for TBG-T4. Acidification of DNS-TBG at pH 4.4 produced a decrease in both Trp and DNS fluorescence whereas DNS-TBG-T4 at the same pH showed a large change in DNS fluorescence but no change in Trp fluorescence. Low guanidinium chloride concentration unfolded the unliganded molecule as indicated by a decrease of Trp and DNS fluorescence, whereas the fully occupied TBG showed only a decrease of DNS fluorescence. Exposure of TBG and TBG-T4 to trypsin showed a twofold increase in the rate of tryptic hydrolysis for TBG-T4 indicating that T4 binding either increased the exposure to the solvent of some lysyl or arginyl residues or increased their susceptibility to the trypsin action. These data provide additional evidence that T4 binding enhances the molecular stability of TBG. An effect on TBG conformation which was previously described probably explains the increased stability. The decrease in dansyl fluorescence of DNS-TBG-T4 probably is due to a local effect of acid or GdmCl unrelated to protein unfolding.

Alpha-Globulins↗
PubMed1980

[Gestalt therapy of complaints].

People can express their suffering voicing it, complaining with their body, with gestures, movements; for alerts eyes it is even more comprehensive and true than words. Complaints that human beings are capable of expressing are not so many, there are only a handful, and this work intends to be exhaustive in its exposition. It is possible to complain against third persons. It is also possible to do so against oneself assuming either the intransigent attitude of a father who judges a son who does not fulfill his expectancies, or as a son who resents the paternal demands which he feels he cannot comply. Other kind of complaints include physical symptoms, either isolated (cephalea, dysnea, urticaria) or constituting syndromes or illnesses. Losses suffered are also a source of complaints, whatever the lost object might be (person, situation, material things or a part of oneself). It can be mourned because of its absence, or else by feeling guilty of the real or imaginary damage inflicted or else by feeling indisolubly linked to it with a phantom tie. Other types of complaints are the feeling of dependancy towards something oppressive, be it a substance, such as alcohol, smoking, drugs or overeating, or it may be a person or a situation. In view of the compulsive addiction characteristics with which the subject lives, it is possible to assimilate this dependancy and the feeling of oppression and damage to the link with a toxic.

Female↗
PubMed1975

Defective thyroglobulin synthesis in an experimental rat thyroid tumor: iodination and thyroid hormone synthesis in isolated tumor thyroglobulin.

Purified rat tumor thyroglobulin from the experimental rat thyroid tumor, line 1-1C2, was studied for its thyroid hormone content after in vivo and in vitro iodination and compared with normal and desialylated normal rat thyroglobulin. Tumor thyroglobulin had a very low sialic acid and iodine content; after in vivo iodination it contained only small amounts of triiodothyronine (T3) and no detectable thyroxine (T4). After in vitro iodination with 125I it showed a distribution of T3 and T4 very similar to that of normal and desialylated normal thyroglobulin iodinated in vitro. In vitro iodination dissociated tumor and desialylated normal thyroglobulin to a greater extent than normal thyroglobulin. Tumor tissue, on the other hand, showed considerable iodinating activity in the 105,000 X g pellet when studied with exogenous acceptors. These results are compatible with a role for sialic acid in the maturation and migration of thyroglobulin to the iodination site, rpovided that the intracellular distribution of the iodinating enzymes are normal.

Animals↗
PubMedDate not supplied

Engineered liposomes and virosomes for delivery of macromolecules.

In order to utilize virosomes or proteoliposomes for the delivery of drugs or macromolecules to specific pathologic target cells we elaborated a system to shuttle drugs to solid tissue (liver) as well as to the macrophages, a crucial cellular compartment of the immune system. Using virosomes prepared from the P3HR1 strain of Epstein-Barr virus, we demonstrated that these particles fused with human hepatocarcinoma cell line Li7A and therefore might be used as drug vectors. Furthermore, we report that proteoliposomes prepared by reconstituting in a cocktail of phosphatidylserine-phosphatidylcholine the anion transporter band 3 protein markedly increased the phagocytic activity of macrophages in culture. This could represent a new device to be used as a drug delivery system to enhance specific macrophagic functions.

Anion Exchange Protein 1, Erythrocyte↗
PubMedDate not supplied

Fusion of EBV with the surface of receptor-negative human hepatoma cell line Li7A permits virus penetration and infection.

Our preliminary data suggest that Epstein-Barr virus (EBV) is able to bind to and fuse with the surface membranes of hepatoma cell line Li7A. In order to obtain further evidence, we utilized the relief of rhodamine fluorescence to monitor whether fusion would also take place when Li7A cells were exposed to experimental conditions such as neutral or low pH. It is well known that for some viruses, protonation in the endosomal compartment is needed to trigger the fusion. We show, furthermore, that the rate and extent of fusion are not affected by pretreatment of the cells with agents known to elevate the lysosomal and ensodomal pH, such as chloroquine or NH4Cl (lysosomotropic agent). By indirect immunofluorescence assay, in addition, we confirmed the binding of the EBV to the Li7A cell surface membrane. We attempted finally to correlate the above processes with successful infection of Li7A cells by EBV detected using the polymerase chain reaction technique. In spite of the apparent lack of viral receptor CD21, these nonlymphoid cells appeared susceptible to EBV penetration and infection through fusion with the plasma membrane at the surface of the cells.

Antibodies, Monoclonal↗
PubMedDate not supplied

Role of Akata cell membrane fluidity in susceptibility to Epstein-Barr virus infection.

Infection by Epstein-Barr virus (EBV), a B lymphotropic human herpesvirus, of its target cells is initiated by the binding of the viral envelope glycoprotein gp350/220 to a 145-kDa cell membrane glycoprotein (CD21, CR2) which also serves as the receptor for the complement fragment C3d (Fingeroth et al., 1984; Nemerow et al., 1987). We used the fluorescent probe 1-6-diphenyl-1,3,5-hexatriene (DPH), extremely sensitive to the polar environment, in order to analyse the membrane viscosity distribution in single cells of two lymphoid cell lines, Raji and Akata. Lipid analysis on both cell lines showed a slightly lower cholesterol:phospholipid molar ratio on Akata than on Raji cells. Measurements of cell fluidity by DPH polarization in native cells and after cholesterol enrichment indicated that the apparent Akata membrane viscosity was lower than the viscosity of Raji cells. To examine the possibility that this difference could be correlated to a difference in the behaviour of Akata and Raji cells in expressing EBV early antigens, both lines were superinfected with the EBV non-transforming P3HR1 strain. We report here evidence that lipid composition can regulate EBV entry into cells.

Antigens, Viral↗
PubMedDate not supplied

Early steps in fusion between Epstein-Barr virus and a human hepatoma cell line (Li7A).

Epstein-Barr virus, the causative agent of mononucleosis and several human cancers, infects cells via complement receptor type 2 (CR2). Expression of this receptor is restricted to B lymphocytes, some epithelial cells and immature thymocytes; expression of CR2-like proteins has been also found on T cells. In the present report, we identified the presence, on the membrane of Li7A cells, of a novel EBV receptor distinct from CR2 capable of triggering fusion with EBV virions with more rapid kinetics than that found with lymphoblastoid cells (Raji).

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Attempts to use liposomes and RBC ghosts as vectors in drug and antisense therapy of virus infection.

Selective targeting of drugs or oligonucleotide for the treatment of viral diseases or cancer is the objective of new strategies that pursue therapy optimization and reduction of toxicity. In this work we report two protocols based on encapsulation of anti-human immunodeficiency virus drugs within targeted liposomes or erythrocytes. Both have been shown to be effective for the specific delivery of drugs or oligonucleotide in the treatment of viral infection.

Adenine↗
PubMedDate not supplied

Early events of fusion between Epstein Barr virus and human lymphoblastoid cells (Raji) detected by R18 fluorescence dequenching measurements.

Relief of fluorescence self-quenching was used to monitor fusion (14) of Epstein Barr virus (EBV) with Raji cells after exposure of the virus to a variety of experimental conditions such as neutral or low pH, enzymatic modification of the viral spike glycoproteins, or inhibition of the protein kinase C (PKC) activity. Incubation of the virus at pH 5.9 prior to the binding to the cell membrane led to a significant enhancement of fusion with the plasma membrane. Treatment of Raji cells with an agent known to elevate the endosomal and lysosomal pH (lysosomotropic agent) (3, 12) partially prevented fusion at neutral pH. Desialylation of EBV significantly reduced the extent of fusion with Raji cells. Protein kinase C inhibitor reduced EBV fusion with Raji cells, while treatment with the tumor promotor and the PKC activator TPA caused an increase in the final extent of fusion. Our results suggest that EBV fuses with lymphoblastoid cells in the endocytic vesicles after being rapidly internalized and that protein kinase C is involved in the process of viral entry into cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMedDate not supplied

Use of the fluorescent probe Laurdan to investigate structural organization of the vesicular stomatitis virus (VSV) membrane.

We have used 6-dodecanoil-2-dimethylaminonaphtalene (Laurdan) to study the membrane fluidity of Vesicular Stomatitis Virus (VSV) during virus activation at acidic pH 5.8). The fluorescence properties of Laurdan provide a unique possibility to study lipid organization because of the different excitation and emission spectra of this probe in the gel and liquid crystalline phase. Acidification to pH 5.8 (the pH which triggers VSV fusion with target membranes) generates a decrease in VSV membrane fluidity that could be reversed perfectly after neutralization. We conclude that lipid reorganization of the VSV membrane in the endocytic vesicles is needed for virus activation.

2-Naphthylamine↗
PubMedDate not supplied

Immunohistochemical evaluation of CD31 in human cystic radicular lesions and in keratocysts.

Platelet-endothelial cell adhesion molecule-1 protein (PECAM-1/CD31) is expressed in numerous physiological and pathological processes characterized by an increase of vascular permeability, and in normal and tumour tissues. CD31, member of the immunoglobulin super-family that mediates cell-to-cell adhesion, is a transmembrane glycoprotein, 130-140 kDa, also know as platelet-endothelium cell adhesion molecule (PECAM-1). CD31 is a ligand for CD38 and plays a role in thrombosis and angiogenesis. CD31 is strongly expressed in endothelial cells and weakly expressed in megakaryocytes, platelets, occasional plasma cells, lymphocytes (marginal zone B-cells, peripheral T-cells) and neutrophils. The present study evaluates the angiogenetic processes which are accompanied by an expansion of cystic radicular and keratocystic lesions of the jaw bone. Twelve subjects with maxillary cysts (8 males and 4 females) with an average age of 43 years were selected by the Chieti University Oral Surgery Department. The surgical samples taken were subjected to histological and immunohistochemical analysis. The histological evaluation confirmed the diagnosis of radicular cystisis and keratocystisis. The immunohistochemical analyses were positive for CD31 protein in all the lesions analysed, even though they had different intensities. Using a semiquantive analysis it was possible to highlight, in the radicular cyst samples, an intense expression of the vascular component both in the inflamed area and the adjacent stroma. The lesions with cheratin content showed newly-formed, rather modest, vascularity both in the area showing slight inflammation, where the cellular component is prevalent, and in the adjacent areas showing no sign of inflammation. Therefore, in our observations, angiogenesis could take on a primary role in the development of cystic lesions of the jaw bones. The differences of CD31 expression, in all samples, would advise for a wider monitoring able to evaluate the possible use of such a protein as a diagnostic marker.

Adult↗