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Biomedical subjects

F Vita

Publications and source records attributed to F Vita.

At least 19 recordsLinked to original sources
PubMed2004

Actin-dependent tumour cell adhesion after short-term exposure to the antimetastasis ruthenium complex NAMI-A.

Imidazolium trans-imidazoledimethylsulphoxidetrachlororuthenate (NAMI-A) was tested in vitro on the pro-adhesive properties, evaluated as resistance to trypsin treatment, which is a bona fide measure of adhesion strength, of KB and HeLa carcinoma cell lines and on human polymorphonuclear neutrophils (HPMN). NAMI-A increased the pro-adhesive activity of KB cells at 0.001 mM concentration, after few minutes incubation and this effect was not influenced by the vehicle used for cell challenge, neither did it depend on NAMI-A concentration or on temperature. The same effect occurred on HeLa cells at 0.01 mM NAMI-A. This effect, detected at concentrations up to 100 times lower than those necessary to block cells at the G(2)-M premitotic phase of cell cycle, or to inhibit matrix metalloproteinase release or cell invasion, was not related to ruthenium uptake by tumour cells. HeLa cells and healthy HPMN, following short exposure to 0.1 mM NAMI-A, assumed a different shape, with the extrusion of filopodia (HeLa) and of large lamellopodia (HPMN), which increased their interactions with the substrate. This effect was attributed to stabilisation, altered turnover and sensitivity to cytochalasin D of actin filaments. Provided that adhesion is associated with cell motility and invasion, these data suggest that NAMI-A may exert antimetastatic properties at concentrations lower than those observed in the lungs at the end of a conventional intraperitoneal treatment in vivo.

Actin Cytoskeleton↗
PubMed2004

Spectroscopic ellipsometry study of liquid crystal and polymeric thin films in visible and near infrared.

In this work, we propose spectroscopic ellipsometry as a suitable method for measuring optical properties in soft materials, polymers and liquid crystals, specially selected for use in photonics applications. We show the results of our measurements on some multilayered samples, in the range from visible to the near-IR region, of interest for telecom applications. We point out potentialities and limits of the technique and compare the obtained results with another experimental method, the m-lines spectroscopy, and/or with existing data in the literature. The results about the optical parameters for the analysed materials (the nematic liquid crystal 5CB, one commercial and one lab made optical polymer, and an Indium Tin Oxide film) are useful and interesting by themselves. In fact, as a paradigmatic example, we briefly discuss how an incomplete knowledge of this kind of data can lead to a wrong design of a Bragg grating device. However, more than in the provided data, we put the interest of the present analysis in the warnings about spectroscopic ellipsometry utilization and eventually the necessity of getting complementary information.

Journal Article↗
PubMed2004

Dynamical behaviour of holographic gratings with a nematic film--Polymer slice sequence structure.

We have studied the dynamical response of a new kind of holographic grating to a pulsed electric field. The structure, named POLICRYPS, consists of a sequence of homogeneous polymer slices separated by liquid-crystal films. We have found that both the rise and fall response times depend on the pulse duration and amplitude of the applied electric field. We propose a phenomenological explanation for this behaviour, outlining the possibility of getting response times of the order of 100 micros by properly choosing the pulse shape. Results are very interesting for developments in which POLICRYPS gratings could be proposed as basic elements in photonic devices for telecom applications, and induce to a deeper analysis of the microscopic interaction between liquid crystal and polymer interfaces in these samples.

Journal Article↗
PubMed2003

Oral and intraperitoneal acute toxicity studies of yessotoxin and homoyessotoxins in mice.

The acute toxicity of yessotoxin (YTX), homoyessotoxin (homoYTX) and 45-hydroxy-homoyessotoxin (45-OH-homoYTX) has been studied in comparison to that of okadaic acid (OA), the main diarrhogenic toxin, both after intraperitoneal (i.p.) and oral administration. After i.p. administration, homoYTX and YTX showed similar lethality (LD(50)=444 microg/kg and 512 microg/kg), higher than that of OA (LD(50)=225 microg/kg), while 750 microg/kg of 45-OH-homoYTX did not cause death. OA induced the already known toxic signs: before death, mice were motionless and cyanotic; small intestine and liver damage were shown at post-mortem. Mice treated with YTX and homoYTX were restless and jumped before death; necroscopy did not show major changes. After oral treatment, 2 mg/kg of OA induced diarrhoea and body weight loss, causing 4/5 deaths; necroscopy and/or histology revealed degenerative lesions to small intestine, forestomach and liver (confirmed by increased plasma transaminase), but no myocardium alterations. On the contrary, the oral treatment with YTX (1 and 2 mg/kg) and its derivatives (1 mg/kg) did not cause any death or signs of toxicity, except some ultrastructural myocardiocyte alterations, adjacent to capillaries, such as cytoplasmic protrusions (YTX, 1 and 2 mg/kg), fibrillar alteration (YTX, 1 mg/kg) or mitochondria assemblage (45-OH-homoYTX). Altogether, our data show that YTX and its derivatives are less toxic than OA after acute oral and i.p. treatments, at doses which may represent up to 100 times of the possible human daily intake.

Administration, Oral↗
PubMed1996

Subcellular localization of the small GTPase Rab5a in resting and stimulated human neutrophils.

The evidence that small GTPases of the Rab family are regulators of vesicle traffic which can influence various cell functions prompted us to investigate the potential role of one of these proteins, Rab5a, in human neutrophils. In this paper we show that a large amount of Rab5a is present in the cytosol of peripheral blood mature neutrophils. The remaining protein was found to be membrane and azurophilic granule associated. Upon neutrophil challenge with PMA for 10 min the amount of membrane-associated Rab5a was upregulated while the cytosolic content of the protein concomitantly decreased. These findings support the hypothesis that Rab5a could be involved in the mechanism of neutrophil activation by modulating the rate of endocytosis and/or vesicle fusion.

Cytoplasmic Granules↗
PubMed1995

A role for eosinophils in the pathogenesis of skin lesions in patients with food-sensitive atopic dermatitis.

BACKGROUND: Atopic dermatitis is associated with skin and blood eosinophilia, but the role of eosinophils in the pathogenesis of the skin lesions is poorly understood. METHODS: To determine whether eosinophils play a role in the pathogenesis of the skin lesions in atopic dermatitis, we studied the relationship between the severity of the disease and both the number and the extent of activation of eosinophils in 15 patients with food-sensitive atopic dermatitis. Furthermore, this relationship was re-evaluated in eight of these patients who, after a period of elemental diet or total parenteral nutrition, showed significant clinical improvement. RESULTS: A clear relationship was found between the number of light-density eosinophils and the severity of the disease both during the active disease and after clinical improvement. Furthermore, we describe an adhesion-stimulating activity for eosinophils in patients' plasma, which does not change after recovery. CONCLUSIONS: Taken together, these observations strongly indicate that eosinophils play a pivotal role in the pathogenesis of the skin lesions in atopic dermatitis. In particular, the light-density phenotype seems to be an essential feature of eosinophils involved in this process. The adhesion-promoting activity that we observed in the patients' plasma could be important in the recruitment of eosinophils from the blood into the skin.

Adult↗
PubMed1994

[Applications of digital radiology to pediatric uroradiology].

The authors report their 4 years' experience with a computerized digital radiographic system based on photostimulable phosphor plates which was used mostly in pediatric radiology. Major protection advantages were observed for uroradiology where high kV (90-95 kV) and very low exposure times (0.02-0.010s) were used. With this radiographic technique reduced exposure parallels increased graininess due to quantum mottle: the two variables must therefore be balanced not to decrease diagnostic accuracy. During our 4 years' experience, 368 examinations were performed on pediatric patients: 252 micturition cystourethographs, 81 urograms and 35 retrograde pyelographs. None of these examinations needed to be repeated due to over/under-exposure and image quality was always high, in spite of a light "noise". Digital radiography in pediatric urology allows radiation dose to be reduced and high quality images to be acquired and is therefore likely to take over conventional radiologic techniques.

Adolescent↗
PubMed1993

[Cephalometry and digital radiography. Technical note].

Conventional and digital lateral teleradiographs of the skull were performed on 6 consecutive patients (3 men and 3 women). The study was aimed at comparing the diagnostic capabilities of the two imaging techniques to measure points and angles, as derived from different cephalometric analyses (see text for details). These variables were analyzed by three different operators: for both techniques, 18 cephalometric tracings were made, including a total of 414 points and 36 angles. Correlation coefficients between the two types of measurements (points and angles) were calculated; Wilcoxon's non-parametric test was also used. This study demonstrates digital radiography to be superior to conventional radiography to detect cephalometric landmarks, which is especially evident in the evaluation of the so-called "questionable" landmarks: the latter were 15 of 23 with conventional radiography and 9 of 23 with digital radiography. On the other hand, correlation coefficients and significance of the values of the considered angles were in close agreement with the two techniques. Therefore, its simultaneous demonstration of anatomical structures of different thickness--i.e., bone and soft tissues--and its lower exposure dose make digital radiography the diagnostic procedure of choice in cephalometrics, especially in the pediatric age, as well as in monitoring the patients.

Adolescent↗
PubMed1986

In vitro interactions of opioid peptides with phospholipids. II. Additional spectral evidence.

The interaction of leu-enkephalin with phosphatidylserine has been studied with ultraviolet and circular dichroism spectroscopy methods as well as with fluorescence anisotropy techniques. The data reported hereunder confirm the existence of binding between the two species, and also support the hypothesis that not only the tyrosine, but also the phenylalanine residue in the leu-enkephalin molecule is involved in peptide-lipid interaction. In addition, ultraviolet and CD evidence, taken together, tend to suggest that both aromatic residues are bound, with a different degree of involvement, to the same region of the lipid molecule. The data reported are discussed in terms of the interaction model previously proposed by us.

Binding Sites↗
PubMed1986

In vitro interaction of opioid peptides with phospholipids. III. The role of lipid.

The binding of tritiated Leu-enkephalin to phosphatidylserine and phosphatidylcholine vesicles, both unmodified and modified by the incorporation of free fatty acid, has been studied by steric exclusion chromatography, ultraviolet difference spectroscopy and fluorescence anisotropy. The results obtained tend to confirm that both ionic and hydrophobic interactions are important in the binding phenomena. On the other hand, it seems likely that steric factors play a very limited role in the recognition of the phospholipid by the opioid peptide. Finally, these results confirm the existence of three complexes of different size, as already demonstrated. But, unlike the previously presented results, they stress the importance of the larger of the three complexes formed through binding.

Chromatography, Gel↗
PubMed1985

Peripheral enkephalin hydrolysis in different animal species: a comparative study.

Using column and thin layer chromatography, plasma hydrolysis of leu-enkephalin has been studied in man and several laboratory animals. The hydrolysis kinetics determined in the various species examined are considerably different. In addition, also the enzyme forms evidentiated, their molecular weight distribution and relative ratios have been found to vary greatly in the animals under test. Our data suggest that the widely different hydrolysis kinetics reported by various authors are attributable to the differences between species, rather than to differences in the analytical techniques employed.

Aminopeptidases↗
PubMed1985

Enkephalin binding systems in human plasma. II: Leu-enkephalin serum albumin interaction.

Enkephalins are released into the bloodstream of mammals by the adrenal medulla. Once they are in the blood, these peptides undergo a fairly rapid hydrolysis by several plasma-contained enzymes. However, a fraction of the enkephalins present in the plasma are bound to the serum albumin, and the bound peptides are almost completely intact even after a long incubation in the presence of serum enzymes. Therefore, it seems possible that the interaction with serum albumin can maintain the functional integrity of the circulating enkephalins. Moreover, serum albumins are extremely well characterized proteins and, therefore, a suitable model for the study of protein-enkephalin interaction in general. The present work is a first step in the study of the mechanism of serum albumin-enkephalin interaction. Apparently, ionic parameters are important in the binding phenomenon. Furthermore, the serum albumin conformational status seems to be relevant in the binding. Finally, the binding is followed by a limited rearrangement of the protein molecule.

Acylation↗
PubMedDate not supplied

Isolation of a murine metastatic cell line and preliminary test of sensitivity to the anti-metastasis agent NAMI-A.

We have isolated a new cell line (metGM) obtained from the spontaneous lung metastases of the mouse MCa mammary carcinoma. MetGM is a stable cell line which, after one year from its isolation, grows in vitro in suspension, forming cell aggregates, with cells that show irregular blabbing borders, active protein synthesis and convoluted nuclei and which have the capacity of invading matrigel membranes on which they give rise to a network of branching colonies. The preliminary study of the effects of the anti-metastasis ruthenium complex NAMI-A on metGM showed no direct cytotoxicity, with a mild reduction of cell proliferation, independent of the concentration of the ruthenium complex and not evident before 24 hours from treatment. A 10% DNA fragmentation was also measured on metGM cells 24 hours after challenge for 1 hour with 10(-5)M NAMI-A, suggesting that this compound is probably capable of apoptosis in a metastasis-derived cell line. Besides these effects on a limited percent of the cell population, NAMI-A changed the shape of the metGM cells and these alterations might account for the non-cytotoxic anti-metastatic properties of this innovative ruthenium complex. Thus MetGM appears to be a novel cell line suitable for the in vitro study of compounds endowed with anti-metastatic properties and for the development of new drugs with this activity.

Animals↗