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Biomedical subjects

G Ori

Publications and source records attributed to G Ori.

5 recordsLinked to original sources
PubMed2002

Inhibitory effect of synthetic histatin 5 on leukotoxin from Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans is a gram-negative bacterium strongly implicated in the pathogenesis of juvenile periodontitis. This periodontal pathogen synthesizes a leukotoxin that destroys human polymorphonuclear leukocytes (PMNs), and this toxin is thought to be responsible for the virulence of A. actinomycetemcomitans. It was therefore of interest to assess whether major virulence factors of periodontal pathogens were neutralized by salivary components. This study focuses on the effect of histatins, components of the nonimmune oral defense system, on leukotoxin activity. Leukotoxin was extracted with polymyxin B from freshly grown anaerobic cultures of A. actinomycetemcomitans strain Y4. PMNs isolated from blood of healthy human volunteers were incubated in a cytotoxicity assay containing PMNs (10(7) cells/ml) and leukotoxin preparation (0-500 microg/ml) in Hanks' balanced salt solution at 37 degrees C for 0-120 min with or without synthetic histatin 5 (0-500 microM). Cytotoxicity was measured by release of lactate dehydrogenase (LDH) at different time intervals. Histatin 5 neutralized the toxic effect of the leukotoxin preparation in a concentration-dependent manner, with an IC(50) value of 150 microM. When PMNs were preincubated with histatin 5 (300 microM), washed and subsequently exposed to leukotoxin, no protective effect was observed. This observation suggests a mechanism of inhibition whereby histatin 5 either directly neutralizes the leukotoxin or interferes with the leukotoxin-PMN interaction. The inhibitory effect of histatin 5 on leukotoxic activity may suggest a new biological function of histatins in the oral cavity as a naturally occurring secondary antibiotic.

Adult↗
PubMed1999

The effects of nicotine and age on replication and viability of human gingival fibroblasts in vitro.

The aim of the present study was to examine: (1) the effects of nicotine on human gingival fibroblasts (HGF); (2) differences between smokers (> or = 10 cigarettes/day at least for 5 years) and non-smokers; (3) differences between patients of different age. HGF were obtained, through biopsies during periodontal surgical procedures, from 15 patients which were divided in 4 groups: 4 patients, smokers aged < or = 25 years; 4 patients, non-smokers aged < or = 25 years; 3 patients, smokers aged > or = 40 years; 4 patients, non-smokers aged > or = 40 years. Nicotine has been tested in 3 different concentrations: 6 microg/ml; 60 microg/ml; 600 microg/ml. To assess cells viability, the neutral red (NR) test was used; to evaluate cell proliferation, the Hoechst test was employed. After 48 h of nicotine exposure, it was found that 600 microg/ml nicotine was strongly cytotoxic to HGF of all groups, with a significant reduction of both proliferation and viability of cells versus control. Comparison between groups of the same age: when comparing untreated HGF (i.e., control values) of smokers < or = 25 years versus non-smokers < or = 25 years, cell proliferation, but not viability, was found to be increased in smokers. Both viability and proliferation of control cells of smokers > or = 40 years were increased versus non-smokers > or = 40 years. HGF of non-smokers < or = 25 years, when exposed to nicotine 600 microg/ml, have less viability and proliferation than HGF of smokers of the same age. Comparison between groups of different age: In the smoker group, untreated HGF (i.e., control values) had similar viability and proliferation, irrespective of age, but nicotine 600 microg/ml kills more HGF in smokers < or = 25 years than in smokers > or = 40 years. In non-smokers, untreated HGF < or = 25 years replicate less, but are not less viable than HGF > or = 40 years. When challenged with nicotine 600 microg/ml, HGF < or = 25 years were less viable than HGF > or = 40 years. From this study, it appears that the smoking history and the patient age could be relevant for final evaluation of the results, since HGF from smokers are less sensitive to nicotine than HGF from non-smokers, and cells from older donors are more resistant to nicotine than cells from younger donors.

Adult↗
PubMed1998

Search for life on Mars.

A multi-user integrated suite of instruments designed to optimize the search for evidence of life on Mars is described. The package includes: -Surface inspection and surface environment analysis to identify the potential Mars landing sites, to inspect the surface geology and mineralogy, to search for visible surficial microbial macrofossils, to study the surface radiation budget and surface oxidation processes, to search for niches for extant life. -Subsurface sample acquisition by core drilling -Analysis of surface and subsurface minerals and organics to characterize the surface mineralogy, to analyse the surface and subsurface oxidants, to analyse the mineralogy of subsurface aliquots, to analyse the organics present in the subsurface aliquots (elemental and molecular composition, isotopes, chirality). -Macroscopic and microscopic inspection of subsurface aliquots to search for life's indicators (paleontological, biological, mineralogical) and to characterize the mineralogy of the subsurface aliquots. The study is led by ESA Manned Spaceflight and Microgravity Directorate.

Europe↗