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Biomedical subjects

P Valenti

Publications and source records attributed to P Valenti.

At least 109 records · Page 6Linked to original sources
PubMed1990

Interaction of lactoferrin with Escherichia coli cells and correlation with antibacterial activity.

It has been established that the antimicrobial activity of lactoferrin towards Escherichia coli is enhanced by a direct contact between the protein and the microbial cell and that, in the case of E. coli K-12 strains, an antibacterial activity of lactoferrin unrelated to iron withdrawal is present. Evidence is now reported that lactoferrin binds to surface structures expressed in E. coli K-12 strains grown in either an "excess" or "stress" of iron. Under the experimental conditions used, lactoferrin binding both in the apo and in the iron-saturated form yields a maximum of 1.6 X 10(5) bound molecules/E. coli K-12 cell; the amount of lactoferrin bound does not depend on the expression of the iron-regulated outer membrane proteins. In contrast, lactoferrin does not bind to E. coli clinical isolates. Apo-lactoferrin (at 500 micrograms/ml in a chemically defined medium) inhibits the growth of E. coli K-12 strains but not of clinical isolates. These findings suggest that the antibacterial activity of the protein could be associated to its binding to the cell surface.

Absorption↗
PubMed1990

Anatomic basis of a dorso-commissural flap from the 2nd, 3rd and 4th intermetacarpal spaces.

This study relates to an island skin-flap constructed on the dorsal aspect of the hand, between the heads of the 2nd, 3rd, 4th and 5th metacarpals. The vascular pedicle consists of the subcutaneous fatty tissue of the dorsal aspect of the proximal phalanx. This fatty tissue is richly vascularized by the dorsal branches of the proper palmar digital artery and by the periarticular circle of the proximal interphalangeal joint. The point of rotation of the flap is situated at the level of the proximal interphalangeal joint. The length of the pedicle allows the skin flap to cover losses of substance of the dorsal aspect of the middle and distal phalanges. Its chief advantage is that it does not sacrifice the proper palmar digital artery.

Blood Vessels↗
PubMed1990

Effect of polyelectrolytes on entry of Escherichia coli HB101 (pRI203) into HeLa cells.

The role of charged molecules in the entry mechanism of enteroinvasive bacteria was studied using Escherichia coli HB101 harboring a plasmid (pRI203) containing the Yersinia pseudotuberculosis invasion region as an experimental model. We investigated the effect of several anionic and cationic polyelectrolytes on the initial steps of infection of HeLa S3 cells by E. coli HB101 (pRI203). Experiments in which the polyions were added to cell monolayers together with bacteria showed that invasion was only slightly influenced by anions whereas cations strongly enhanced bacterial entry. DEAE-dextran, histone and poly-L-lysine were the most effective enhancers producing an up to five-fold increase in the number of both infected cells and internalized bacteria. Moreover, addition of the active polycations at different stages of infection demonstrated that their action took place during the attachment step, whereas internalization was not affected.

Cell Division↗
PubMed1990

Effect of desferrioxamine B, a metal chelating agent, on rhabdovirus multiplication.

It has been suggested that the antiviral activity shown by chelating agents towards different viruses is probably related to the action on viral nucleic acid polymerases which require metal ions as essential cofactors. Desferrioxamine B, a metabolite from Streptomyces pilosus which chelates ions (Fe3+, Al3+, Cu2+, Zn2+, Co2+) from intracellular and external compartments, has been tested for its activity on the multiplication of VSV and rabies virus in CER cells. While desferrioxamine B was ineffective on rabies virus multiplication, it was shown to reduce plaque formation, cytopathic effect and viral yield by VSV at both low and high multiplicity of infection. The activity of the drug was not due to a direct action on virions outside the cells, but was probably related to an alteration in the delicate balance of intracellular ions which could in turn be critical for VSV multiplication.

Animals↗
PubMed1990

[Transrectal echography and simultaneous uroflowmetry in the study of male urination. Considerations on 254 consecutive cases].

The authors report on a series of 254 consecutive male patients who underwent transrectal US, sometimes combined with uroflowmetry, for the study of micturitonal phase. 170 patients were studied with both techniques. In 118 patients, there was complete agreement between the two methods about presence and degree of flow obstruction; partial disagreement was observed in 48 patients and complete disagreement in 4. On 44/52 patients with partial/complete disagreement diagnostic cystouretrography was performed. Our results demonstrate high agreement between the two techniques, except in case of micturition deficit with columnar hypertrophic bladder and in obstructive pathologic conditions of anterior urethra.

Adult↗
PubMed1989

Synthesis and quantitative structure-activity relationships of analeptic agents related to dimefline.

Some new dimefline-type derivatives have been synthesized and their pharmacological activity, as well as their distribution coefficients have been determined. The distribution coefficients of a number of previously published analogue compounds have also been measured and the QSAR analysis of the whole set has been carried out. The results of such analysis allow to point out which factors are influencing the biological activity of this group of compounds.

Animals↗
PubMed1989

Growth and adsorption of Streptococcus mutans 6715-13 to hydroxyapatite in the presence of lactoferrin.

The growth of Streptococcus mutans 6715-13 in a rich medium (Todd Hewitt broth) was drastically reduced by addition of apo-lactoferrin (apo-Lf); this effect was bacteriostatic and reversible by saturation of Lf with iron. The influence of Lf, salivary proteins (SP) and bovine serum albumin (BSA) on the attachment of Streptococcus mutans to hydroxyapatite (HA) was successively investigated. Sorption of Lf, SP, and BSA to HA was dependent on the protein concentration and reached the end-point at about 80 mg of proteins per gram of HA. Similarly, the number of streptococci adsorbed to HA was correlated to the amount of cells available up to at least 10(7) cells per mg of HA. The adsorption of Lf, SP and BSA on HA reduced the number of attaching S. mutans cells. In particular, SP reduced the adsorption of S. mutans by 30%, whereas pre-coating of HA with apo- or iron-saturated Lf resulted in a three orders of magnitude reduction of S. mutans adsorption to HA, as demonstrated by means of different experimental procedures. The powerful adherence-inhibiting effect of apo-Lf together with its noticeable antibacterial activity towards S. mutans points to a biological significance of these phenomena also in vivo.

Adsorption↗
PubMed1989

[Post-traumatic dislocation of the upper tibiofibular joint. Review of the literature apropos of 6 cases].

This study reviewed 6 cases of post-traumatic dislocation of the superior tibia-fibular joint. It was associated 5 times over six to a tibial fracture or major ligament lesion of the knee. The authors have made a review of the literature on this rare injury. The purpose of this paper is to insist on the necessity of an early diagnosis allowing a simple treatment and good results.

Adolescent↗
PubMed1989

[Ultrasound-guided prostatic biopsy using biplanar transrectal probe. Our experience].

In the last three years we performed more than 200 echo-guided prostatic biopsies using different probes. Recently, thanks to the availability of a bi-planar transrectal probe we have developed a technique that resulted simple rapid well accepted by the patients and above all able to center small prostatic nodules. We have studied with this technique 96 patients performing 120 biopsies. For the biopsy we used a 19 G cutting-needle introduced under local anaesthesia parallel to the probe (linear array) when the needle is on the target we turn on the axial view and we check the position with respect to the center of the lesion, then, returning to the sagittal view we perform 1 to 3 biopsies for microhistological and cytological examination. With this method we have reached a better accuracy of diagnosis.

Biopsy↗
PubMed1988

Bivalent ligand type beta-adrenolytics related to practolol.

The synthesis and pharmacological evaluation of a number of symmetrical bivalent ligand type beta-adrenolytics related to practolol are reported. The best results have been observed with N,N'-bis[3-[2-hydroxy-3-[1-methylethyl)amino]propoxy]phenyl] ethanediamide.

Adrenergic beta-Antagonists↗
PubMed1988

Bis-arenoxypropanolamines as potential beta-adrenolytics: a reinvestigation.

A number of symmetrical as well as asymmetrical bis-arenoxypropanolamines have been synthesized and evaluated for their beta-adrenolytic properties. The pharmacological characterization of these compounds was performed in vitro by direct studies (3H-dihydroalprenolol was used as the specific ligand for beta-receptors), and by determining the beta-blocking capacity on isoproterenol (ISO)-induced increased heart rate (isolated guinea-pig atrium); and in vivo by evaluating the antagonism on ISO-induced hypotension and tachycardia, as well as the intrinsic sympathomimetic activity (ISA) on reserpinized and vagotomized rats. The best result was observed with the simplest derivative, i.e. the bis-phenoxypropanolamine compound, which shows in vitro and in vivo potencies almost comparable to propranolol and, moreover, significant bronchodilating activity.

Adrenergic beta-Antagonists↗
PubMed1988

Enhanced antimicrobial activity of lactoferrin by binding to the bacterial surface.

In order to elucidate the mechanisms involved in the antibacterial activity of lactoferrin, quantitative determinations of siderophore production and lactoferrin adsorption on various bacterial species were performed. The binding of lactoferrin took place both on Gram-positive and Gram-negative species and occurred with bacterial cells grown in stress or in excess of iron. The different degrees of sensitivity to lactoferrin observed could not be directly related to the type and amount of siderophores produced. However, it was possible to find a correlation between the capacity of some strains to bind lactoferrin and their sensitivity to this protein. These data suggest that the binding of lactoferrin on the cell surface can result in an antibacterial activity additional to iron witholding.

Adsorption↗