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Biomedical subjects

G Rivara

Publications and source records attributed to G Rivara.

12 recordsLinked to original sources
PubMed1997

Phytosterol compounds having antiviral efficacy.

The present study is focused on the antiviral action patterns obtained in vitro with synthetic sterolester comprising compositions on virus-bearing host cell-lines. Appropriate cell-lines were infected with HIV-1, human Cytomegalovirus (HCMV) and Herpes simplex virus (HSV). There appears to exist a clear anti-infective efficacy for a selected number of such ester compounds, provided they are formulated into spontaneously dispersible concentrates, which in aqueous dilution engender ultramicro-emulsions having micelles in the lowest nanosize region. A significant protection against HIV-induced cytopathogenic effect was demonstrated employing a methyltetrazolium salt reduction assay on HIV-infected MT4 cells when they were incubated with such concentrates. A similar effect was evidenced with the same concentrates, when preincubating concentrated virus, but not the target cells. Antiviral activity appeared to be remarkable also on HCMV infections in vitro, where a blocking effect on immediate-early antigen expression in fibroblast monolayers could be observed. Similarly, HSV-associated glycoprotein antigen in VERO cells also suggests that virus-cell interaction and/or virus multiplication could have been blocked at a very early point of time. This would be quite different from antiviral action-patterns studied so far and imputed into the current models of explanation. Proper solubilization of the employed phytosterol compounds is essential for achieving the described activity modes. The often recommended liposome formulations would not be well suited for such compounds and such purpose, since after dilution they produce aqueous macro-emulsions, only. Furthermore, liposome formulations tend to coalesce and exhibit Marangoni effects.

Antiviral Agents↗
PubMed1996

Marigenol-concentrates comprising Taxol and/or Taxan esters as active substances.

Marigen is a Swiss Research Company based in Riehen (Canton of Basle). It has developed and tested a Solubilization System for its phytosteryl ester compounds having antitumor and antiviral/virucidal activity. By formulating spontaneously dispersible concentrates, which comprise such compounds, it is now possible to produce thermodynamically stable, aqueous ultramicroemulsions which achieve outstanding bioavailability and bio-reactivity for the active principles comprised in these Marigenol-Concen-trates. As a consequence, unwanted side-effects are drastically reduced in therapeutical use or even completely absent, and the economy of the system permits a remarkable optimization of the dose-efficacy relationship and hence also of drug safety.

Alkaloids↗
PubMed1995

Phytosterols as growth regulators.

Starting from squalen and gonan structures, nature produces by enzymatic transformation a great variety of P--and subsequently also of "animal" sterols. This wonderful chain of biosyntheses comprises a number of provitamins such as beta-carotene and ergosterol and has an endpoint in the vitamin D compounds ergocalciferol (ercalciol, vit D2) and cholecalciferol (calciol, vit D3). On the other hand, we have has an endpoint the most important compound cholesterol and its derivatives, like androsterone, testosterone and 17 beta-estradiol. The members of this family of chemical compounds perform the most diverse biological functions, if properly "directed" or transported to their respective sites of action. Since all of these compounds are hardly soluble in water, we concentrated our research work on their solubilization and thus on enhancing their bioavailability and bioreactivity. The bioreactivity of P was taken as guiding principle for an investigation into understanding the ways of nature as closely as possible-and, at same time-to interpret the findings in comprehensive context. An effort at integrated system's thinking was made throughout.

Biological Availability↗
PubMed1989

Allergic contact dermatitis from topical corticosteroids.

22 cases of allergic contact dermatitis from topical corticosteroids were observed in Strasbourg and previously published. 7 further cases are reported here and the vehicle and concentration of corticosteroids for patch tests are discussed. A 0.1% concentration in petrolatum seemed adequate for testing the 4 molecules (triamcinolone acetonide, dexamethasone, desonide and amcinonide) responsible for the 7 new cases. In 1 case, several cross-reactions were seen. A corticosteroid screening series permits patch testing of the suspected molecule(s) in a selective way. Without this series, long delays are required to make the correct diagnosis by patch testing. We have reviewed more than 60 papers on corticosteroid allergy published up to now.

Administration, Topical↗
PubMed1987

Contact dermatitis after ultrasonography and electrocardiography.

We report 4 patients who developed allergic contact dermatitis after ultrasound investigations. Patch testing was positive with conducting gels, and in 2 cases with propylene glycol. Contact dermatitis to gels is also seen in electrographic practice and after transcutaneous electrical analgesia.

Aged↗
PubMed1987

Pityriasis lichenoides et varioliformis acuta and acquired toxoplasmosis.

A patient presented with a typical pityriasis lichenoides et varioliformis acuta (PLEVA) and disclosed serological evidence of an active and recent toxoplasmosis. Specific treatment of toxoplasmosis promptly and definitively resolved PLEVA lesions. Serological tests for Toxoplasma gondii should be performed in all PLEVA patients.

Female↗