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D Forciniti

Publications and source records attributed to D Forciniti.

8 recordsLinked to original sources
PubMed2000

Cold cataracts: a naturally occurring aqueous two-phase system.

The cytoplasm of the eye lenses shows a liquid-liquid phase transition similar to the one observed in aqueous two-phase systems. This phenomenon is known as cold cataracts. We have studied the solution behavior of the main protein fractions that constitute the lenses' cytoplasm using small-angle neutron scattering and dynamic light scattering. Our results provide evidence that an intricate balance of forces underlines the physical phenomena responsible for the optical properties of the lenses and for the phase transition that is observed as the temperature is lowered below some critical value. These forces include solvent-mediated forces besides the more conventional Coulombic and dispersion forces. This study suggests that solvent mediated forces must be included to successfully model liquid-liquid phase transitions like the ones observed in cold cataracts or in aqueous two-phase systems.

Animals↗
PubMed2000

Effects of Cosolvents and pH on Protein Adsorption on Polystyrene Latex: A Dynamic Light Scattering Study.

Dynamic light scattering was used to study the adsorption of two proteins with different surface properties (IgG and HSA) on negatively charged polystyrene latex. The proteins were adsorbed from water and from water/methanol and water/glycerol mixtures at various pH. Some striking differences between the adsorption behaviors of the proteins were observed. Whereas the thickness of the adsorbed layer of HSA was extremely sensitive to pH and solvent composition, that of IgG was not. IgG mainly showed an end-on orientation on polystyrene whereas several different surface orientations are suggested for HSA under different conditions. The addition of methanol inhibited the adsorption of HSA on the latex, but it did not affect the adsorption of IgG. In contrast, the addition of glycerol increased the thickness of the adsorbed layers of both proteins. So, the orientation of IgG on the latex is insensitive to pH but is a function of the kind of solvent whereas both pH and solvent strongly affect the adsorption of HSA. This is a puzzling result since both cosolvents should equally affect the adsorption of both proteins if the dominant forces for adsorption are the same. Therefore, we concluded that, whereas hydrophobic interactions are the dominant force in the adsorption behavior of HSA, van der Waals forces are the main forces involved in the attachment of IgG to the lattices. Copyright 2000 Academic Press.

Journal Article↗
PubMed1997

A small-angle neutron scattering study of gamma-crystallins near their isoelectric point.

In this paper, a small-angle neutron scattering study of gammaII-crystallins near their isoelectric point is presented. The experiments were carried out using protein concentrations of 5.7-85.7 mg/ml at temperatures in the range 11 -60 degrees C. The experimental data were analyzed using an ellipsoidal model for intraparticle correlations and the mean spherical approximation for interparticle correlations. Our studies revealed that gammaII-crystallins have a thick hydration layer, which is possibly due to the special arrangement of polar and ionic groups on their surface. The temperature scan shows that, as a result of relatively strong attractive forces, clusters of two, three, or higher oligomers are present below 20 degrees C. Our results suggest that protein clusters, with a distinctive hydration layer, form a protein-rich phase that separates from a protein-lean phase as the temperature is decreased below some threshold value.

Animals↗
PubMed1991

Analysis of polymer molecular weight distributions in aqueous two-phase systems.

The partitioning of proteins and other biomaterials between two aqueous phases containing polyethyleneglycol and dextran is a strong function of the molecular weight of the two polymers. Although both polymers are polydispersed (especially Dx) most theoretical treatments refer only to the average molecular weight (number or mass) and assume that the molecular weight distribution of each polymer is the same in both phases. In this work the molecular weight distribution of each polymer is the same in both phases. In this work the molecular weight distributions of four stock solutions of PEG (4000, 6000, 10,000 and 20,000) and four stock solutions of Dx (10,000, 40,000, 110,000 and 500,000) were measured using High Performance Gel Chromatography. The measurements were repeated on the phases formed by the polymer solutions after they were mixed and allowed to equilibrate. The molecular weight distribution of the Dx differed in the top and bottom phase; both differed from that of the stock solution. Although we believe that the molecular weight distribution for PEG also differs in the top and bottom phases, we were unable to determine this within the resolution of our instruments.

Dextrans↗
PubMed1991

Temperature dependence of the partition coefficient of proteins in aqueous two-phase systems.

We report the partition coefficients of lysozyme, chymotrypsinogen-A, albumin and catalase in sixty four Polyethyleneglycol/Dextran/Water systems at 4, 25 and 40 degrees C. We found that the partition coefficients of the four proteins generally increase with increasing temperature. The influence of temperature on the partition coefficient seems to be highly dependent on the kind of protein which is partitioned and on the total polymer concentration, but does not, in general, depend on the molecular weight of the polymers. The partition coefficients of small and hydrophilic proteins like lysozyme and chymotrypsinogen-A are only slightly affected by changes in temperature, while the partition coefficients of bigger and more hydrophobic proteins like albumin and catalase are strongly affected by changes in temperature. The results suggest the incorporation of attractive forces (possible electrostatic) into a model previously reported by us.

Albumins↗
PubMed1990

Investigation of affinity partition chromatography using formate dehydrogenase as a model.

The enzyme formate dehydrogenase (FDH) was purified from the crude extract of Candida boidinii by affinity partition chromatography. The partition coefficient, K, of the enzyme was selectively increased by adding polyethylene glycol-Procion Red HE3b as an affinity ligand to the mobile phase in the chromatographic column. The increased K value led to early elution of the enzyme-ligand complex and separated the target protein from the main peak of the contaminants.

Candida↗
PubMedDate not supplied

[Acute respiratory obstruction caused by laryngo-tracheal candidiasis in a HIV-positive patient].

The authors report a case presenting highly complex symptomatology. In fact, when the patient came under observation he had had a cough, dyspnea, dysphagia and dysphonia for approximately three months. The biopsy, taken by direct laryngoscopy, indicated the presence of candidiasis in the subglottic and tracheal areas. Laboratory tests indicated complete anergy and patient tested serum positive to HIV. During hospitalization acute dyspnea arose requiring emergency tracheostomy.

Acquired Immunodeficiency Syndrome↗