Biomedical subjects

François Malecaze

Publications and source records attributed to François Malecaze.

9 recordsLinked to original sources

PubMed2006

Iris-supported phakic lenses (rigid vs foldable version) for treating moderately high myopia: randomized paired eye comparison.

PURPOSE: To compare refractive performance of Artisan (Ophtec, Groningen, The Netherlands) or Verisyse phakic intraocular lens and its foldable version, Artiflex (Ophtec), for the correction of moderately high myopia. DESIGN: Randomized pilot study. METHODS: setting: Institutional practice. patient population: Thirty-one patients with myopia that ranged from -6 to -14 diopters (D). interventional procedure: One eye was implanted with an Artisan phakic intraocular lens (PIOL) and the other with an Artiflex PIOLs. main outcome measures: Primary outcome measure was the percentage of eyes with uncorrected visual acuity (UCVA) of >20/40 at one year after the operation. Main secondary outcome measures were the safety index, the change of two lines or more of best spectacle-corrected visual acuity (BSCVA) and the endothelial cell count. RESULTS: No intraoperative complications were noticed. One year after surgery, the percentage of eyes with UCVA of >20/40 was 51.6% (16/31 patients) for Artisan-treated eyes and 77.4% (24/31 patients) for Artiflex-treated eyes (P = .033). One month after surgery, this same percentage was 42.9% (13/31 patients) and 77.4% (24/31 patients), respectively (P = .004). The safety index at one year was 1.13 +/- 0.24 for Artisan-treated eyes and 1.12 +/- 0.21 for Artiflex-treated eyes, which is a difference that was not statistically significant (P = 0.742). At one year after surgery, the changes of two lines or more of BSCVA and the endothelial cell loss were similar for both groups. CONCLUSION: To correct moderately high myopia, the Artiflex lens provides a faster visual recovery and a better UCVA than does the Artisan lens. The safety of the lens should be supported by an enlarged sample size and a longer follow-up period.

Adult↗

PubMed2006

Soluble HLA-G1 inhibits angiogenesis through an apoptotic pathway and by direct binding to CD160 receptor expressed by endothelial cells.

HLA-G is a major histocompatibility complex class Ib molecule whose constitutive tissue distribution is restricted mainly to trophoblast cells at the maternal-fetal interface during pregnancy. In this study, we demonstrated the ability of the soluble HLA-G1 (sHLA-G1) isoform to inhibit fibroblast growth factor-2 (FGF2)-induced capillary-like tubule formation. Using a rabbit corneal neovascularization model, we further showed that sHLA-G1 inhibits FGF2-induced angiogenesis in vivo. We also demonstrated that sHLA-G1 induces endothelial cell apoptosis through binding to BY55/CD160, a glycosylphosphatidylinositolanchored receptor expressed by endothelial cells. Furthermore, we showed that the specific CL1-R2 anti-CD160 monoclonal antibody mimics sHLA-G1-mediated inhibition of endothelial cell tube formation and induction of apoptosis. Thus, the engagement of CD160 in endothelial cells may be essential for the inhibition of angiogenesis. sHLA-G1/CD160-mediated antiangiogenic property may participate in the vascular remodeling of maternal spiral arteries during pregnancy, and, given that we found that CD160 is strongly expressed in the vasculature of a murine tumor, it offers an attractive therapeutic target for preventing pathologic neovascularization.

Amino Acid Sequence↗

PubMed2006

Extracellular signal-regulated kinase-dependent proliferation is mediated through the protein kinase A/B-Raf pathway in human uveal melanoma cells.

Mutated B-Raf-mediated constitutive activation of ERK1/2 is involved in about 66% of cutaneous melanoma. By contrast, activating mutations in B-RAF are rare in ocular melanoma. This study aimed to determine the role of wild-type B-Raf ((WT)B-Raf) in uveal melanoma cell growth. We used cell lines derived from primary tumors of uveal melanoma to assess the role of (WT)B-Raf in cell proliferation and to characterize its upstream regulators and downstream effectors. Melanoma cell lines expressing (WT)B-Raf and (WT)Ras grew with similar proliferation rates, showed constitutive activation of ERK1/2, and had similar levels of B-Raf expression and B-Raf kinase activity as melanoma cell lines expressing the activating V600E mutation ((V600E)B-Raf). They were equally as sensitive to pharmacological inhibition of MEK1/2 for cell proliferation and transformation as (V600E)B-Raf cells. siRNA-mediated depletion of Raf-1 did not affect either ERK1/2 activation, whereas siRNA-mediated depletion of B-Raf reduced cell proliferation by up to 65% through the inhibition of ERK1/2 activation, irrespective of the mutational status of B-Raf. Pharmacological inhibition of cAMP-dependent protein kinase (PKA) and siRNA-mediated depletion of PKA greatly reduced B-Raf activity, ERK1/2 activation, and cell proliferation in (WT)B-Raf cells, whereas it did not affect (V600E)B-Raf cells, demonstrating a key role of PKA in mediating (WT)B-Raf/ERK signaling for uveal melanoma cell growth. Moreover, inactivation or depletion of PKA did not affect Rap-1 activity, and Rap-1 depletion did not affect either B-Raf activity or ERK1/2 activation. This ruled out a role for Rap1 in the PKA-mediated B-Raf/ERK activation in (WT)B-Raf cells. Finally, we demonstrated the importance of cyclin D1 in mediating PKA/(WT)B-Raf signaling for cell proliferation. Altogether, our results suggest that the PKA/B-Raf pathway is a potential target for therapeutic strategies against (WT)B-Raf-expressing uveal melanoma.

Cell Proliferation↗

PubMed2006

Corneal ectasia after photorefractive keratectomy for low myopia.

OBJECTIVE: To alert ophthalmologists of the possibility of an aggravation of forme fruste keratoconus after photorefractive keratectomy (PRK). DESIGN: Clinical case report. INTERVENTION: Standard bilateral PRK for low myopia. MAIN OUTCOME MEASURES: Corneal topography, corneal thickness, and visual acuity. RESULTS: Corneal ectasia occurred bilaterally after PRK. Retrospective analysis of preoperative videokeratography indicated the existence of forme fruste keratoconus on the left eye. CONCLUSIONS: This article is the first case report of a bilateral corneal ectasia after PRK for low myopia. Even if there is no direct proof to demonstrate that PRK has worsened the evolution of keratoconus, the safety of the PRK procedure in forme fruste keratoconus must be considered.

Adult↗

PubMed2005

The xenobiotic-metabolizing enzymes arylamine N-acetyltransferases in human lens epithelial cells: inactivation by cellular oxidants and UVB-induced oxidative stress.

The human arylamine N-acetyltransferases NAT1 and NAT2 are important xenobiotic-metabolizing enzymes involved in the detoxification and metabolic activation of numerous drugs and chemicals. NAT activity depends on genetic polymorphisms and on environmental factors. It has been shown that low NAT-acetylation activity could increase the risk of age-dependent cataract, suggesting that NAT detoxification function may be important for lens cells homeostasis. We report here that the NAT acetylation pathway may occur in human lens epithelial (HLE) cells. Functional NAT1 enzyme was readily detected in HLE cells by reverse transcription-polymerase chain reaction, Western blotting, and enzyme activity assays. NAT2 mRNA and enzymic activity were also detected. We investigated whether oxidants, known to be produced in HLE cells during oxidative stresses and involved in age-dependent cataract formation, decreased endogenous NAT1 and NAT2 activity. The exposure of HLE cells to peroxynitrite led to the dose-dependent irreversible inactivation of both NAT isoforms. Exposing HLE cells to continuously generated H(2)O(2) gave a dose-dependent inactivation of NAT1 and NAT2, reversible on addition of high concentrations of reducing agents. UVB irradiation also induced the reversible dose-dependent inactivation of endogenous NAT1 and NAT2, reversible on addition of reducing agents. Thus, our data suggest that functional NAT1 and NAT2 are present in HLE cells and may be impaired by oxidants produced during oxidative and photooxidative stresses. Oxidative-dependent inhibition of NATs in these cells may increase exposure of lens to the harmful effects of toxic chemicals that could contribute to cataractogenesis over time.

Arylamine N-Acetyltransferase↗

PubMed2003

Opposite long-term regulation of c-Myc and p27Kip1 through overactivation of Raf-1 and the MEK/ERK module in proliferating human choroidal melanoma cells.

Although there is no current evidence for ras gene mutation in choroidal melanoma, there is an increasing body of evidence indicating that deregulated intracellular signalling pathways are involved in choroidal melanoma pathogenesis. The various components of the linear Raf/MEK/ERK signalling pathway have been implicated in various tumours. We therefore investigated the role of Raf-1 and the MEK/ERK module in the proliferation of human normal choroidal melanocytes (NCM) and cells from the ocular choroidal melanoma (OCM-1) cell line. OCM-1 cells proliferated four times faster than NCM. High basal activation of the MEK/ERK module was observed in unstimulated OCM-1 cells, whereas rapid and persistent activation was detected after serum stimulation, throughout the 24-h period of culture. In contrast, the activation of MEK/ERK was barely detectable in unstimulated NCM and occurred late (6 h) after the stimulation of cell proliferation. Inhibition of Raf-1 and MEK1/2 activation by pharmacological approaches and of the production of Raf-1 and ERK1/2 by antisense oligonucleotide approaches demonstrated that Raf-1 and the MEK/ERK module controlled proliferation in OCM-1 cells, but not in NCM. OCM-1 cells produced very low levels of p27Kip1, whereas NCM produced constant, high levels of p27Kip1. The inhibition of Raf-1 or MEK1/2 induced a large increase in p27Kip1 in OCM-1 cells, associated with an arrest of cell proliferation. Levels of c-Myc production were high and constant in OCM-1 cells and low in NCM, in contrast to what was observed for p27Kip1. The inhibition of both Raf-1 and MEK1/2 induced a decrease in c-Myc production and downregulated c-Myc activity by preventing c-Myc phosphorylation in OCM-1 cells. We conclude that Raf-1 and the MEK/ERK module control the production of both p27Kip1 and c-Myc, and the activation of c-Myc for OCM-1 cell proliferation.

Cell Cycle Proteins↗

PubMed2003

Impaired killing of HCMV-infected retinal pigment epithelial cells by anti-pp65 CD8(+) cytotoxic T cells.

PURPOSE: Host defense against infection by human cytomegalovirus (HCMV) is ensured in great part by cytotoxic CD8(+) T lymphocytes (CTLs) directed against the tegument protein pp65. The hyperimmediate release of incoming pp65 into the major histocompatibility complex (MHC) class I pathway after fusion of the virus with the cell membrane provides a very early mechanism of defense. In retinal pigment epithelial (RPE) cells HCMV is known to enter through endocytosis. This study was conducted to determine whether this means of penetration into the cells would allow the virus to elude immune surveillance. METHODS: Infection of RPE cells with HCMV AD169 was performed for 6 hours, 48 hours, and 8 days. Expression of intracellular pp65 in RPE cells and in the astrocytoma reference cell line U373MG was evaluated by flow cytometry, fluorescence microscopy, and Western blot analysis. Killing of both HCMV-infected cell lines by HLA-A2-restricted CD8(+) CTLs directed against pp65 was monitored by (51)Cr-release assays. RESULTS: RPE cells were not lysed by CTLs directed against incoming pp65, contrary to U373MG. Moreover, both cell lines were not killed by anti-pp65 CTLs later after infection, because of the MHC class-I-downregulating effect of HCMV unique short (US2-11) proteins. CONCLUSIONS: In RPE cells, both HCMV entry through endocytosis and the immunosuppressive effect of US proteins could allow the virus to evade immune surveillance at any stage of infection, which could promote viral spreading within the retina.

Blotting, Western↗

PubMed2002

Screening of blood from potential organ and cornea donors for viruses.

Prospective nucleic acid tests were carried out for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) using the COBAS Amplicor HIV-1 and HCV tests (Roche Diagnostics, Meylan, France) on potential organ (n=113) and cornea (n=368) donors in France to evaluate their performance and suitability for use as a complement to routine serological tests. Blood samples were collected from organ donors with preserved cardiac function after verification of cerebral death. Blood samples were collected from cornea donors post-mortem within 48 hr after death. An internal control was added to the samples before extraction to monitor each individual polymerase chain reaction (PCR). The nucleic acid tests were always interpretable in organ donors and negative in all except in 2 anti-HCV positive patients. One had an indeterminate HIV p24 antigen but was negative for HIV RNA. HIV and HCV RNA were not found in cornea donors with a negative serology but indeterminate molecular results were frequent in this group (17.6%). Cornea donors also gave significantly more (14.4%) indeterminate serological results than organ donors (1.8%) (P<0.001). This was due to the poor quality of the blood samples collected post-mortem. However, there was no correlation between indeterminate results of serological and molecular tests. There were 16/19 (84%) indeterminate serological results for HIV and 4/4 (100%) for HCV that were negative by PCR. Thus, nucleic acid tests could be useful for qualifying a donor whose serological results are indeterminate. The extraction procedures on post-mortem specimens and/or blood collection must be changed to improve the performance of nucleic acid tests.

Cornea↗

PubMed2002

Expression of the murine msr/apj receptor and its ligand apelin is upregulated during formation of the retinal vessels.

We have recently identified a new G protein-coupled receptor, msr/apj, whose transcripts are detected in the endothelium of the primary blood vessels and the newly forming heart (Mech. Dev. 1999;84:199). Its expression during formation of the embryonic vasculature incited us to investigate whether expression of the receptor also increased during the formation of retinal vessels, which occurs postnatally in the mouse. Interestingly, msr/apj transcripts are indeed associated with the forming vessels and trace the centrifugal extension of the superficial vasculature. We also show that expression of the endogenous ligand apelin is upregulated at the leading edge of vessel formation.

Adipokines↗