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Biomedical subjects

F Bonté

Publications and source records attributed to F Bonté.

At least 19 recordsLinked to original sources
PubMed2003

Decreased expression of keratinocyte beta1 integrins in chronically sun-exposed skin in vivo.

BACKGROUND: Chronic exposure to ultraviolet (UV) radiation induces changes in the skin structure which are mostly found in the superficial dermis and at the dermal-epidermal junction. Keratinocytes and fibroblasts contribute both to the synthesis and to the degradation of the molecules important for the integrity of this skin site. While several studies have reported on alterations of dermal components and of the functions of fibroblasts in vivo and in vitro after UV exposure, recent data suggested that keratinocytes could be the main skin cell type involved in the photoageing process. OBJECTIVES: In this study, we analysed the expression of two keratinocyte molecules namely, beta1 integrin (a proliferation marker) and involucrin (a differentiation marker) in sun-exposed and sun-protected facial skin of 16 healthy patients undergoing facial lifting. METHODS: Methods included histology, immunohistochemistry and quantitative reverse transcriptase-polymerase chain reaction analysis. RESULTS: Sun-exposed skin displayed the characteristic morphological and molecular features of dermal photoageing, compared with sun-protected skin, including dermal elastosis, diminished fibrillin and type VII collagen expression. Analysis of the epidermis in sun-exposed vs. sun-protected skin showed no histological differences, but dramatic changes in the expression of beta1 integrin and involucrin. In sun-exposed skin, expression of beta1 integrin protein by epidermal basal cells was reduced, paralleling a downregulation of beta1 integrin mRNA, whereas involucrin protein expression was greatly enhanced in the superficial epidermal cell layers. Interestingly, the ratio between involucrin and beta1 integrin protein expression was consistently increased in sun-exposed skin sites. CONCLUSIONS: Collectively these results demonstrate that epidermal homeostasis is impaired by chronic UV exposure, and define beta1 integrin expression as a molecular marker of the epidermal photoageing process.

Aged↗
PubMed2000

Efficacy of the bisbenzylisoquinoline alkaloids in acute and chronic Trypanosoma cruzi murine model.

We have shown previously that daphnoline and cepharanthine are active against Trypanosoma cruzi and inhibited trypanothione reductase. The effects of oral treatments with daphnoline, cepharanthine and benznidazole were examined in Balb/c mice infected with T. cruzi acutely and chronically. In acute infections, parasitaemia was significantly reduced in the daphnoline-treated mice compared with controls and benznidazole-treated mice. The parasitological cure rate was increased in mice treated with daphnoline. Fifty days after infection, the negative serological response in both models was significantly different for the three tested drugs. Daphnoline showed the highest negative serological rate (48%). In chronically infected mice treated with daphnoline, we were unable to detect parasites in 70% of mice. The results obtained of oral treatment of daphnoline suggest that this bisbenzylisoquinoline may be useful in the treatment of acute and chronic Chagas' disease. This was not seen with cepharanthine, an excellent trypanothione reductase inhibitor.

Acute Disease↗
PubMed1998

Age-related functional and structural changes in human dermo-epidermal junction components.

Cultured normal human keratinocytes obtained from 14 facial skin biopsies of donors aged 9-79 y were used to study the influence of donor age on the integrin receptors, cell adhesive properties in vitro, and type VII collagen synthesis. Immuno-spectrofluorimetric quantitation of integrins showed a decrease in the beta1- and beta4-subunits in low (0.08 mM) and high (1.8 mM) calcium conditions with aging. Calcium ions decreased the fluorescence intensity by relocating integrins at cell boundaries. Measurements of adhering cells showed that adhesion to bovine serum albumin-, type IV collagen- or laminin 1-coated plastic surfaces initially increased until donor age reached 30 y and then decreased. Specific adhesion to type IV collagen and laminin 1 did not vary with age, but the increase in adhesion to type IV collagen produced by manganese ions increased with age, suggesting an age-dependent feature of beta1 integrin. Synthesis of type VII collagen, increased or not by TGFbeta1 (10 ng per ml), did not vary with the donor age. Global normalized principal component analysis showed that variables related to integrins were strongly correlated, as were those of adhesion. Pre-embedding immunoelectron microscopy of freshly isolated keratinocytes showed that certain hemidesmosomes from aged cells had little or no reaction with anti-beta4-chain antibody. Post-embedding type IV collagen immunostaining and image analysis showed less type IV collagen in adult dermo-epidermal junctions. These findings indicate that there are structural and functional changes in the dermo-epidermal junction components with aging, probably giving a less effective epidermal anchoring system.

Adolescent↗
PubMed1997

Existence of a lipid gradient in the upper stratum corneum and its possible biological significance.

The internal stratum corneum lipid composition was investigated in relation to depth in vivo in healthy human volunteers by extraction following one, three or five strippings. Automated multiple development high-performance thin-layer chromatography (AMD-HPTLC) and gas chromatography (GC) followed by normalized principal component analysis showed a decrease in the amount of lipids extracted after one, three and five strippings. Between levels 0, 1, 3 and 5 the stratum corneum lipid composition showed an increase in phospholipids and cholesterol-3-sulphate at level 3, a decrease in ceramide, cholesterol and free fatty acids after level 1, and a slight decrease in sterol esters at level 3. Lipids extracted after three strippings displayed a characteristic composition with an increase in the proportion of phospholipids and cholesterol-3-sulphate. Free fatty acid analysis in relation to depth revealed a decrease in the amounts of C14:0, C16:0, C16:1, C18:0 and C18:1 between levels 1 and 5 and an increase in the C24:0. A decrease in the unsaturated/saturated chain ratio with depth was also observed, reflecting a greater decrease in unsaturated than saturated free fatty acids. A decrease in the ratios of free fatty acids to cholesterol and free fatty acids to ceramides after three and five strippings, respectively, and previously reported results, confirm the importance of this level of stratum corneum lipids in skin barrier properties.

Adult↗
PubMed1997

Thermotropic phase behavior of in vivo extracted human stratum corneum lipids.

The thermotropic phase behavior of lipids extracted either in vivo from inner forearm (SCLE) or plantar callus (PC) was investigated by differential scanning calorimetry and small angle X-ray diffraction. PC composition was chromatographically modified (MPC) by eliminating the more polar lipids in order to evaluate their role. Analysis of composition confirms the potential use of PC as a source of stratum corneum lipids. MPC and SCLE exhibit similar differential scanning calorimetry (DSC) profiles with a main transition around 50 degrees C attributed to the solid-to-liquid phase transition of the ceramides. The absence of a transition around 50 degrees C for PC suggests the possible perturbation of ceramide packing by the significantly high proportion of phospholipids. X-ray data suggest a high miscibility of sebum components in stratum corneum lipids with possible modification of chain packing. The MPC patterns show a lipid phase separation which underscores the role of polar lipids in cholesterol/free fatty acids/sterol esters/ceramides structural cohesion.

Adult↗
PubMed1997

Protective effect of curcuminoids on epidermal skin cells under free oxygen radical stress.

Curcuminoids from Curcuma longa L. (Zingiberaceae) protected normal human keratinocytes from hypoxanthine/ xanthine oxidase injury. Since curcuminoids synergistically inhibited nitroblue tetrazolium reduction, a decrease in superoxide radical formation leading to lower levels of cytotoxic hydrogen peroxide was proposed as an explanation for this protective effect.

Antioxidants↗
PubMed1997

Expression of Bcl-2 and Bax in cultured normal human keratinocytes and melanocytes: relationship to differentiation and melanogenesis.

Keratinocyte differentiation and melanogenesis are two major cellular processes by which the epidermal compartment of the skin acquires its protective properties. Bcl-2; an oncoprotein involved in the regulation of apoptosis, has been shown to be expressed by keratinocytes and melanocytes. To determine whether Bcl-2 and Bax, a protein which heterodimerizes with Bcl-2, may control these epidermal functions, we investigated the expression of these two oncogenes in cultivated human keratinocytes and melanocytes from the same donors, respectively induced to differentiate and to produce melanin. As determined by cytometry, we observed that these two cell types constitutively express the two proto-oncogenes. Quantification of Bcl-2 antigen sites per cell showed that Bcl-2 expression is higher in keratinocytes than in melanocytes. An increase in transglutaminase activity, a marker of keratinocyte terminal differentiation initiating cornified envelope formation, was accompanied by a decrease in Bcl-2 levels without significant modification of Bax expression. In melanocyte cultures, stimulation of the dopa-oxidase pool, a key enzyme in melanin synthesis, paralleled Bcl-2 down-regulation and Bax up-regulation. This led us to conclude that the expression of these two oncogenes and their cellular ratio are closely involved in keratinocyte differentiation and melanogenesis.

Cell Culture Techniques↗
PubMed1996

Simarouba amara extract increases human skin keratinocyte differentiation.

An aqueous extract of Simarouba amara was studied for its activity on the differentiation of human skin keratinocytes. Submerged and air-exposed treated keratinocyte cultures displayed a more highly differentiated histoarchitecture, with presence of ultrastructural differentiated elements, than untreated controls. Immunohistochemistry of involucrin and activation of transglutaminase activity provided further evidence for the increase in corneocyte envelope formation observed ultrastructurally. Lipid analysis of air-exposed cultures revealed an increase in the cholesterol sulphate, cholesterol and ceramide contents. After 4 weeks of treatment on the hemiface of volunteers, the capacitance and transepidermal water loss evaluation revealed the potential interest of this extract for improvement of skin hydration. Electron microscopic examination of the corneocyte envelope on tape strips confirmed its actions. Taken together these data demonstrated that an aqueous extract of S. amara increases human keratinocyte differentiation.

Cell Differentiation↗
PubMed1996

[Antoine Auguste and Louis Deriard, pharmacists and numismats from Lyon].

Antoine Auguste Deriard (1796-1873), was a pharmacist having a pharmacy, place des jacobins in Lyon then a store of raw materials for pharmacy. He gathered more than 3000 biographical notes on VIP from Lyon, was a famous numismat and collector of rare books. His son Louis (1825-1891) also a great collector of coins, medals and autographs ran its drugstore rue Dubois then rue Tupin in Lyon from 1854 to 181. Its sales figures with the well known Guilliermond pharmacy was between 400-1200 F a year (between 1858-1860). A. A. and L. Deriard struck each a personnal token (cupper, 32 mm diameter) whose description is given.

France↗
PubMed1996

Age-related response of human dermal fibroblasts to L-ascorbic acid: study of type I and III collagen synthesis.

Stimulation of the synthesis of type I and III collagens by 0.15 mM L-ascorbic acid (AA) was investigated in primary cultures of dermal fibroblasts form 30 females aged between 19 and 70 years. At this concentration allowing maximal stimulation, fibroblast cultures responded to this agent by an increase in collagen secretion, but to a lower extent for type III compared to type I, leading to an increase in the type I/III collagen ratio. We showed that AA stimulation of type I and III collagen secretion decreased in a statistically significant linear manner with donor age (slope = 1.9; p = 0.0014 and slope = -0.5; p = 0.0164, respectively). We also observed an age-related AA stimulation of the cell-associated collagen pool for type I collagen but not for type III (slope = 0.29; p = 0.015). This might indicate that a reduced ability of fibroblasts to secrete the newly synthesized type I collagen is involved in loss of the cellular response to AA stimulation. Analysis of AA stimulation as a function of body site showed that during aging, the loss of AA stimulation of type I and III collagen synthesis was more for periauricular (slope = 2.7; p = 0.0280 and slope = -0.8; p = 0.0309, respectively) than for mammary skin (slope = 2.1; p = 0.0071 and slope = 0.1; p = 0.7337, respectively). This led us to consider that UV-exposed cutaneous sites may accelerate cellular dermal aging in terms of response to AA, making this parameter a quantitative indicator of human dermal cell aging.

Adult↗
PubMed1995

Analysis of all stratum corneum lipids by automated multiple development high-performance thin-layer chromatography.

An optimized gradient enabling the separation of all stratum corneum lipids by automated multiple development on HPTLC plates is presented. An initial isocratic step separates sebum lipids. This is followed by a 25-step development using a gradient with a polarity range of methanol-water to hexane. Application to in-vivo extracted and isolated stratum corneum lipids demonstrates the possible quantification of the lipid classes with a "one-experiment" separation.

Adult↗
PubMed1995

[Comparative activity of asiaticoside and madecassoside on type I and III collagen synthesis by cultured human fibroblasts].

Type I and III collagens are the major components of skin dermis. Skin aging is related mainly to a decrease in type I collagen levels. Collagen I also plays an important role in wound healing. An enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of secretion of type I and III collagen in human fibroblast cultures with or without asiaticoside and madecassoside. Normal adult dermal fibroblast cultures were established using the explant method from a skin (lifting) sample obtained from a 50 year-old woman. Fibroblasts were grown to confluence in supplemented E 199 medium and after 24 hours of growth, products were added in serum free medium containing 0.15 mM sodium ascorbate. The media were then collected and type I and III collagen secretion levels determined. Kinetics of type I and III collagen secretion led to determine the effects to asiaticoside and madecassoside after 48 hours for collagen I secretion and 72 hours for collagen III. Two triterpenes with an ursenoic skeleton, asiaticoside and madecassoside, were shown to stimulate collagen secretion. Type I secreted collagen (for 10(4) fibroblasts per 48 hours) was increased for 25-30% with asiaticoside and madecassoside. Interestingly, only Madecassoside was able to increase significantly collagen III secretion.

Anti-Infective Agents↗
PubMed1994

Human epidermal cells progressively lose their cardiolipins during ageing without change in mitochondrial transmembrane potential.

Mitochondria dysfunction is considered to be a major cause of the modifications that occur during cell ageing. For this reason, cardiolipin, a suitable marker of the chondriome, as well as the mitochondrial transmembrane potential were examined in keratinocytes obtained from 9- to 75-year-old women. The study was carried out by flow cytometry using two fluorescent mitochondria probes: nonyl acridine orange, which binds specifically to cardiolipin, and rhodamine 123, which is incorporated mainly in response to transmembrane potential. Cardiolipin levels in cells from elderly donors (75 years old) would be 57% lower (r = 0.540; P = 0.0002) than those in children (9 years old), while the inner transmembrane potential remained unchanged (r = 0.0394; P = 0.8017). The stability of the membrane potential may be explained by either or both of the following hypotheses: (i) the same pool of organelles able to maintain membrane potential is conserved even when cardiolipin levels decrease (ii) mitochondria membrane potential does indeed decrease with age but is compensated by glycolysis energy production. Finally, it may be stated that the fluorescent probes nonyl acridine orange and rhodamine 123 might be of interest in testing the phenotype of senescent cells and would be useful in screening the role of certain specific genes in cell ageing.

Adolescent↗
PubMed1994

In vitro biosynthesis of type I and III collagens by human dermal fibroblasts from donors of increasing age.

A quantitative study of type I and type III collagen production was carried out on primary cultures of human dermal fibroblasts. Cultures were initiated from facial and mammary skin of 29 women aged between 19 and 68 years. Secreted and cell-associated collagen levels were determined by an enzyme linked immunosorbent assay (ELISA). We found that the secretion of type I and type III collagen decreased linearly with age (r = 0.432; P = 0.0193 and r = 0.502; P = 0.0147, respectively). There was a 29% loss in secretion ability for type I and type III collagen over the 49-year period studied. Furthermore, no significant linear age-related decrease was observed for type I and type III collagen associated with the cellular fraction. The influence of body site was also analysed. We observed a significant linear age-related decrease in type I collagen secretion by mammary skin cells (P = 0.0183 and r = 0.618) as well as facial skin cells (P = 0.0037 and r = 0.699). Furthermore, only mammary skin fibroblasts showed a significant linear age-related decrease in secreted type III collagen (P = 0.106 and r = 0.513). No age-related variations in cell-associated collagen were found.

Adult↗
PubMed1994

[Two prize medals from the "Société de Pharmacie de Paris"].

The author describes two medals from the "Société de Pharmacie de Paris", proving that the medal engraved by Brenet was also used as an award by the Société at the beginning of the 19th century. It also describes for the first time the use of a medal with the effigy of Lavoisier engraved by Caqué as a thesis award from 1871 to at least 1914.

Awards and Prizes↗