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Biomedical subjects

A Fraysse

Publications and source records attributed to A Fraysse.

6 recordsLinked to original sources
PubMed2006

An interdisciplinary approach to investigate the impact of cobalt in a human keratinocyte cell line.

Since in nuclear power plants, risks of skin contact contamination by radiocobalt are significant, we focused on the impact of cobalt on a human cutaneous cell line, i.e. HaCaT keratinocytes. The present paper reports an interdisciplinary approach aimed at clarifying the biochemical mechanisms of metabolism and toxicity of cobalt in HaCaT cells. Firstly, a brief overview of the used instrumental techniques is reported. The following parts present description and discussion of results concerning: (i) toxicological studies concerning cobalt impact towards HaCaT cells (ii) structural and speciation fundamental studies of cobalt-bioligand systems, through X-ray absorption spectroscopy (XAS), ab initio and thermodynamic modelling (iii) preliminary results regarding intracellular cobalt speciation in HaCaT cells using size exclusion chromatography/inductively coupled plasma-atomic emission spectroscopy (SEC/ICP-AES) and direct in situ analysis by ion beam micropobe analytical techniques.

Cell Line↗
PubMed2006

Micro-chemical imaging of cesium distribution in Arabidopsis thaliana plant and its interaction with potassium and essential trace elements.

Cesium as an alkali element exhibits a chemical reactivity similar to that of potassium, an essential element for plants. It has been suggested that Cs phytotoxicity might be due either to its competition with potassium to enter the plant, resulting in K starvation, or to its intracellular competition with K binding sites in cells. Such elemental interactions can be evidenced by chemical imaging, which determines the elemental distributions. In this study, the model plant Arabidopsis thaliana was exposed to 1 mM cesium in the presence (20 mM) or not of potassium. The quantitative imaging of Cs and endogenous elements (P, S, Cl, K, Ca, Mn, Fe, and Zn) was carried out using ion beam micro-chemical imaging with 5 microm spatial resolution. Chemical imaging was also evidenced by microfocused synchrotron-based X-ray fluorescence (microXRF) which presents a better lateral resolution (<1 microm) but is not quantitative. Cesium distribution was similar to potassium which suggests that Cs can compete with K binding sites in cells. Cesium and potassium were mainly concentrated in the vascular system of stems and leaves. Cs was also found in lower concentration in leaves mesophyll/epidermis. This late representing the larger proportion in mass, mesophyll/epidermis can be considered as the major storage site for cesium in A. thaliana. Trichomes were not found to accumulate cesium. Interestingly, increased Mn, Fe, and Zn concentrations were observed in leaves at high chlorosis. Mn and Fe increased more in the mesophyll than in veins, whereas zinc increased more in veins than in the mesophyll suggesting a tissue specific interaction of Cs with these trace elements homeostasis. This study illustrates the sensitivity of ion beam microprobe and microfocused synchrotron-based X-ray fluorescence to investigate concentrations and distributions of major and trace elements in plants. It also shows the suitability of these analytical imaging techniques to complement biochemical investigations of metallic stress in plants.

Arabidopsis↗
PubMed1988

[Not Available].

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France↗
PubMed1986

[Dysmorphic syndrome and vascular dysplasia: an atypical form of type IV Ehlers-Danlos syndrome].

A 29 year old woman was hospitalized for the successive onset of extremely serious vascular accidents: rupture of the gastro-duodenal artery, aneurysm of the posterior tibial artery, discovery of bilateral carotid and vertebral aneurysm with development of a carotid-cavernous fistula. The patient had a very unusual morphotype with dwarfism, white hair and alopecia. Histological investigations failed to reveal atheromatous lesions and by contrast showed involvement of the skin (dermal atrophy) and in the blood vessels fibro-dysplasia of the media. This picture was suggestive of a vascular form of Ehlers-Danlos disease (Sack's syndrome or type IV Ehlers-Danlos disease). This syndrome is characterized by minor skin or joint manifestations replaced by arterial accidents (arterial rupture or development of aneurysms). The etiology is faulty maturation of procollagen III and the diagnosis is based upon fibroblast culture.

Abnormalities, Multiple↗
PubMedDate not supplied

In vivo effects of the GH-releasing heptapeptide GHRP-1 in lambs.

The novel synthetic growth hormone-releasing heptapeptide GHRP-1 is reported to be more potent than growth hormone-releasing hormone (GHRH) in eliciting GH release in vivo in rats and man. However, in ovine pituitary cells in primary culture in a perifusion system, GHRP-1 was 10-fold less active than GHRH. The purpose of this work was to study the effect of GHRP-1 in sheep in vivo. Ovine GH release stimulated by either GHRP-1 or GHRH(1-29)NH2, in eight pre-ruminant lambs, was determined. GHRP-1 was administered at doses of 1.2, 2.4 and 6 nmole/kg by i.v. bolus, and GHRH(1-29)NH2 at 0.3 nmole/kg. Mean+/-s.e.m. peak GH levels in the plasma after injection of saline, 1.2, 2.4, 6 nmole/kg GHRP-1 and 0.3 nmole/kg GHRH were 2.2+/-0.9, 9.3+/-2.5, 8.8+/-2.4, 35.1+/-5.8 and 51.6+/-10.5 ng/mL, respectively. As spontaneous 20 ng/mL peaks were observed, only peaks above this level can be considered as significant. The highest dose of GHRP-1 (6 nmole/kg) elicited oGH release, but its action was surpassed by GHRH 0.3 nmole/kg. Furthermore GHRP-1 and GHRH appear to behave inversely when response amplitudes are considered. Animals exhibiting a strong reaction to GHRH-1, show a correspondingly weak reaction to GHRH and vice-versa. This may reflect differences in intracellular mechanisms at the pituitary level. Our data support the results in vitro that in sheep GHRP-1 is a weaker stimulant of GH secretion than GHRH.

Animals↗