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Biomedical subjects

B Ferrand

Publications and source records attributed to B Ferrand.

At least 19 recordsLinked to original sources
PubMed2004

Laser oscillation with low quantum defect in Yb:GdVO4, a crystal with high thermal conductivity.

A Yb:GdVO4 single crystal was grown by the Czochralski process. Its thermal conductivity was measured by photothermal analysis and reached 8.1 and 7.1 W m(-1) K(-1) along and perpendicular to the c axis, respectively. These values are in good agreement with the predicted ones. The optical spectroscopy of the crystal, such as its absorption and emission cross sections under the two polarizations, its fluorescence lifetime, and its laser parameters, is investigated. Cw laser oscillation is obtained for what is to our knowledge the first time in this material under titanium sapphire pumping at 984 nm. We obtain 420 mW of output power for a 2% output coupler at 1029 nm. With a thin sample, the laser wavelength decreases to 1015 nm. In this case the quantum defect is as small as 2.9%. The weak heat release of the material suggests good prospects for its use in high-power applications.

Journal Article↗
PubMed2003

Two-frequency Er-Yb:glass microchip laser passively Q switched by a Co:ASL saturable absorber.

Passive Q switching of a two-frequency Er3+-Yb3+:glass laser at 1.55 microm with a new Co2+:La(x)Sr(1 - x)Mg(x - y)Co(y)Al(12 - x)O19 crystal as a saturable absorber is demonstrated. We show that, with an extended cavity setup, the beat frequency between the orthogonally polarized laser eigenstates is continuously tunable by adjustment of the retardance of an intracavity birefringence. A similarly built microchip laser emits two-frequency pulses of 6-ns duration with a beat frequency of as much as 19 GHz. Moreover, two-frequency pulses at 777 nm are obtained by second-harmonic generation in a periodically poled lithium niobate crystal. Such pulses can be useful for applications such as Doppler lidar radar.

Journal Article↗
PubMed1990

Post marketing surveillance of zopiclone: interim analysis on the first 10,000 cases in a clinical study in general practice.

The tolerance of zopiclone, a hypnotic belonging to a new chemical group, the cyclopyrrolones, was studied in a follow-up trial in 23,000 insomniac outpatients treated for 3 weeks. The results from the interim analysis of the first 10,000 cases confirm the efficacy and safety of zopiclone under usual prescribing conditions. The average daily dose of zopiclone was 0.97 +/- 0.21 tablet (7.275 +/- 1.575 mg). The study population included 63.1% of female and 36.9% of male patients; the mean age was 52.3 +/- 16.6 years. 93.1% of the patients completed the trial. 8.2% of the patients experienced adverse reactions which resulted in drug discontinuation in only 2.8% of cases. In the global evaluation, the efficacy was rated excellent or good in more than 80% of the patients.

Adolescent↗
PubMed1987

Chronic liver iron overload in the baboon by ferric nitrilotriacetate. Morphologic and functional changes with special reference to collagen synthesis enzymes.

Two baboons receiving intramuscular injections of ferric nitrilotriacetate over a two-year period were compared with two control baboons. The results indicate that in iron-overloaded animals: liver iron excess was major (maximal liver iron concentration values of 42 mumol/100 mg dry weight for both animals vs 1.3 +/- 0.2 (mean +/- SD) in controls) and chronic (for 15 months liver iron concentrations were higher than 15); iron deposition, although less abundant than in sinusoidal cells, was pronounced within parenchymal cells; serum transaminase activities were markedly increased; rare foci of perisinusoidal fibrosis were observed in areas of massive iron overload; and a dramatic decrease in hepatic 4-prolyl-hydroxylase activity was found, in contrast with unchanged glucosyltransferase and galactosyltransferase activities. In conclusion these findings suggest that, in our model, chronic liver iron overload: exerts a marked biochemical cytolytic effect; and does not produce significant hepatic fibrosis, possibly related to an inhibiting effect of ferric nitrilotriacetate complex on 4-prolyl-hydroxylase activity.

Animals↗
PubMed1983

Experimental hepatic iron overload in the baboon: results of a two-year study. Evolution of biological and morphologic hepatic parameters of iron overload.

Four baboons receiving intramuscular iron for 15 months were compared with two control baboons. From the overall two-year observation period the following data emerge: (1) The baboon is a suitable animal for obtaining a massive and chronic iron overload. Liver iron concentrations reached very high levels (ranging from 41.3 to 180.6 mumol/100 mg dry weight vs 1.7 +/- 0.5, mean +/- SEM, in controls), and a major liver iron overload (ie, with concentration values greater than or equal to 18) was present in all four animals for an average period of 16.5 months (range 14-19). (2) When compared with human hepatic iron-overload disorders, iron distribution was similar to that observed in secondary (transfusional) hepatic siderosis since iron deposits were found primarily in sinusoidal cells. However, a marked parenchymal siderosis was also obtained close to that observed in primary (genetic) siderosis. Iron toxicity was present biologically as indicated by an increase in serum transaminases. Histologically, a slight fibrosis was observed in the most heavily iron-overloaded baboon. On the whole, this study of subhuman primates brings new evidence that iron per se has only a minor hepatic damaging effect. It also suggests that the iron-overloaded baboon liver provides a promising tool for the study of liver cell disturbances in human iron overload.

Animals↗
PubMed1982

Comparative study between biochemical and histological methods and image analysis in liver iron overload.

Iron overload has been measured in 100 hepatic biopsies by three different methods: (i) biochemical assay of the liver iron concentration (LIC), (ii) histological grading (HISTO) and (iii) automated image analysis with a Leitz Texture Analysis System by estimating two parameters, (a) the total iron area (TIA) and (b) the first grey level step (FGLS) at which the iron is detected. Image analysis appears as a specific, sensitive, quick, reproducible and valid method.

Autoanalysis↗