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Biomedical subjects

Philippe Bernard

Publications and source records attributed to Philippe Bernard.

34 records · Page 2Linked to original sources
PubMed2004

Pharmacognosy and reverse pharmacognosy: a new concept for accelerating natural drug discovery.

Combinatorial chemistry and high-throughput screening (HTS) have led to the identification of numerous agents that are active and selective in vitro. Identifying drugs that are active in vivo, however, remains a challenge. Traditional medicinal cures based on natural materials have proven useful for many populations worldwide, representing huge and disperse tracts of knowledge that are sometimes neglected in Western research due to differences in the concepts of illness. In this review we introduce a new approach, termed 'reverse pharmacognosy' (from diverse molecules to plants), which can be coupled with pharmacognosy (from biodiverse plants to molecules). Reverse pharmacognosy utilizes new techniques, such as HTS, virtual screening and a knowledge database containing the traditional uses of plants. Integrating pharmacognosy and reverse pharmacognosy in the research process may provide an efficient and rapid tool for natural drug discovery.

Animals↗
PubMed2003

Influence of cultured dermal fibroblasts on human melanoma cell proliferation, matrix metalloproteinase-2 (MMP-2) expression and invasion in vitro.

The dermis is the main site of melanoma invasion. Matrix metalloproteinases (MMPs), especially MMP-2, produced by melanoma or surrounding stromal cells, are essential for the destruction of dermal extracellular matrix. Here, we examined how dermal fibroblasts influenced proliferation, MMP-2 secretion and invasion of human melanoma cell lines in vitro. Human melanoma cell lines M3 Da and M1Dor were cocultured with dermal fibroblasts under non-contact and contact conditions in order to assess both soluble and insoluble factors, respectively. Zymographic analysis showed that the levels of MMP-2 and TIMP-2 in melanoma cells were not altered in non-contact cocultures when compared with those in individual cultures. However, in contact cocultures, the expression of MMP-2 in membrane extracts was enhanced. Under our coculture conditions, dermal fibroblasts failed to upregulate melanoma cell invasion through a three-dimensional type I collagen matrix. Since stromal and cancer cell contacts have been shown to occur after disruption of the extracellular matrix, we hypothesized that fibroblasts may influence melanoma cell invasion after the beginning of tumor progression through the dermis.

Cell Communication↗
PubMed2003

Protein-based virtual screening of chemical databases. II. Are homology models of G-Protein Coupled Receptors suitable targets?

The aim of the current study is to investigate whether homology models of G-Protein-Coupled Receptors (GPCRs) that are based on bovine rhodopsin are reliable enough to be used for virtual screening of chemical databases. Starting from the recently described 2.8 A-resolution X-ray structure of bovine rhodopsin, homology models of an "antagonist-bound" form of three human GPCRs (dopamine D3 receptor, muscarinic M1 receptor, vasopressin V1a receptor) were constructed. The homology models were used to screen three-dimensional databases using three different docking programs (Dock, FlexX, Gold) in combination with seven scoring functions (ChemScore, Dock, FlexX, Fresno, Gold, Pmf, Score). Rhodopsin-based homology models turned out to be suitable, indeed, for virtual screening since known antagonists seeded in the test databases could be distinguished from randomly chosen molecules. However, such models are not accurate enough for retrieving known agonists. To generate receptor models better suited for agonist screening, we developed a new knowledge- and pharmacophore-based modeling procedure that might partly simulate the conformational changes occurring in the active site during receptor activation. Receptor coordinates generated by this new procedure are now suitable for agonist screening. We thus propose two alternative strategies for the virtual screening of GPCR ligands, relying on a different set of receptor coordinates (antagonist-bound and agonist-bound states).

Adrenergic beta-2 Receptor Agonists↗
PubMed2003

Fluorescence resonance energy transfer to probe human M1 muscarinic receptor structure and drug binding properties.

Human M1 muscarinic receptor chimeras were designed (i) to allow detection of their interaction with the fluorescent antagonist pirenzepine labelled with Bodipy [558/568], through fluorescence resonance energy transfer, (ii) to investigate the structure of the N-terminal extracellular moiety of the receptor and (iii) to set up a fluorescence-based assay to identify new muscarinic ligands. Enhanced green (or yellow) fluorescent protein (EGFP or EYFP) was fused, through a linker, to a receptor N-terminus of variable length so that the GFP barrel was separated from the receptor first transmembrane domain by six to 33 amino-acids. Five fluorescent constructs exhibit high expression levels as well as pharmacological and functional properties superimposable on those of the native receptor. Bodipy-pirenzepine binds to the chimeras with similar kinetics and affinities, indicating a similar mode of interaction of the ligand with all of them. From the variation in energy transfer efficiencies determined for four different receptor-ligand complexes, relative donor (EGFP)-acceptor (Bodipy) distances were estimated. They suggest a compact architecture for the muscarinic M1 receptor amino-terminal domain which may fold in a manner similar to that of rhodopsin. Finally, this fluorescence-based assay, prone to miniaturization, allows reliable detection of unlabelled competitors.

Amino Acid Sequence↗
PubMed2003

Chronic pemphigoid gestationis: comparative clinical and immunopathological study of 10 patients.

BACKGROUND: Pemphigoid gestationis (PG) is a rare autoimmune bullous disorder occurring during the last trimester of pregnancy and usually regressive within 3 months after delivery. Prolonged forms of the disease lasting more than 6 months after delivery have been reported as chronic PG. OBJECTIVE: The aim of the present study was to compare the clinical and immunopathological findings between 4 patients presenting a normal regression of the disease after delivery and 6 patients with a chronic course. METHODS: All patients were evaluated and studied by clinical patterns (age, mucosal and cutaneous involvement, obstetrical history, duration of the blistering disease and response to treatment), by direct and indirect immunofluorescence and Western blot. Eight patients were studied by immunoelectron microscopy (IEM) and 3 patients had an indirect IEM. RESULTS: Patients with chronic PG were older, had multigravidity, a history of PG during previous pregnancies, widespread cutaneous eruption and mucosal involvement. Subclass analysis of circulating autoantibodies showed an IgG1 anti-BP180 response in all patients except 1 with disease of 7 years' duration. Direct IEM was positive in 6/8 patients showing a labeling of the lamina lucida, and indirect IEM using colloidal gold probes confirmed the localization of the target antigens to the proximal part of the anchoring filaments in the lamina lucida. CONCLUSION: This study suggests that, even in chronic long-lasting PG, IgG1 remains the predominant subtype of IgG. Therefore no biological and predictable marker of chronicity can be ascertained from this series.

Adult↗
PubMed2003

[Paraneoplastic urticarial vasculitis and renal carcinoma].

Paraneoplastic syndromes have been described in various types of tumours, but are rarely associated with renal cancer. Paraneoplastic cutaneous manifestations, consisting of urticarial vasculitis are exceptional and can sometimes constitute the presenting sign of a completely asymptomatic renal cancer. This vasculitis resolves after curative treatment of the tumour, confirming its paraneoplastic nature. The authors report a case of a paraneoplastic urticarial vasculitis associated with the discovery of an asymptomatic renal carcinoma in a 37-year-old man and discuss paraneoplastic cutaneous syndromes that must be recognised to allow earlier diagnosis of renal tumours.

Adult↗
PubMed2002

Oral pristinamycin versus standard penicillin regimen to treat erysipelas in adults: randomised, non-inferiority, open trial.

OBJECTIVE: To assess the efficacy and safety of oral pristinamycin versus intravenous then oral penicillin to treat erysipelas in patients in hospital. DESIGN: Multicentre, parallel group, open labelled, randomised non-inferiority trial. SETTING: 22 French hospitals. PARTICIPANTS: 289 adults admitted to hospital with erysipelas. RESULTS: At follow up (day 25-45) the cure rate (primary efficacy end point) for the per protocol populations was 81% (83/102) for pristinamycin and 67% (68/102) for penicillin. The planned interim analysis (global one sided type I error 5%) showed that the one sided 97.06% confidence interval of the observed difference (pristinamycin-penicillin) between cure rates (3.3% to infinity ) exceeded the -10% non-inferiority threshold. For the intention to treat populations the cure rate at follow up was 65% (90/138) for pristinamycin and 53% (79/150) for penicillin, with the one sided 97.06% confidence interval of the observed difference between cure rates (1.7% to infinity ) exceeding the -10% non-inferiority threshold. That the lower limit of the confidence interval exceeded the -10% threshold and was also >0 supports the hypothesis that pristinamycin is significantly superior at the 5% level. More adverse events related to treatment, as assessed by the investigators, were reported in the pristinamycin group than in the penicillin group. Most adverse events involved the gastrointestinal tract (nausea, vomiting, and diarrhoea) but were minor and usually did not require discontinuation of treatment. CONCLUSION: Pristinamycin could be an alternative to the standard intravenous then oral penicillin regimen used to treat erysipelas in adults in hospital, with the advantages of oral first line therapy.

Administration, Oral↗
PubMed2002

A comparison of oral and topical corticosteroids in patients with bullous pemphigoid.

BACKGROUND: Bullous pemphigoid is the most common autoimmune blistering skin disease of the elderly. Because elderly people have low tolerance for standard regimens of oral corticosteroids, we studied whether highly potent topical corticosteroids could decrease mortality while controlling disease. METHODS: A total of 341 patients with bullous pemphigoid were enrolled in a randomized, multicenter trial and stratified according to the severity of their disease (moderate or extensive). Patients were randomly assigned to receive either topical clobetasol propionate cream (40 g per day) or oral prednisone (0.5 mg per kilogram of body weight per day for those with moderate disease and 1 mg per kilogram per day for those with extensive disease). The primary end point was overall survival. RESULTS: Among the 188 patients with extensive bullous pemphigoid, topical corticosteroids were superior to oral prednisone (P=0.02). The one-year survival rate was 76 percent in the topical-corticosteroid group and 58 percent in the oral-prednisone group. Disease was controlled at three weeks in 92 of the 93 patients in the topical-corticosteroid group (99 percent) and 86 of the 95 patients in the oral-prednisone group (91 percent, P=0.02). Severe complications occurred in 27 of the 93 patients in the topical-corticosteroid group (29 percent) and in 51 of the 95 patients in the oral-prednisone group (54 percent, P=0.006). Among the 153 patients with moderate bullous pemphigoid, there were no significant differences between the topical-corticosteroid group and the oral-prednisone group in terms of overall survival, the rate of control at three weeks, or the incidence of severe complications. CONCLUSIONS: Topical corticosteroid therapy is effective for both moderate and severe bullous pemphigoid and is superior to oral corticosteroid therapy for extensive disease.

Administration, Oral↗
PubMed2002

Severity and phenotype of bullous pemphigoid relate to autoantibody profile against the NH2- and COOH-terminal regions of the BP180 ectodomain.

Bullous pemphigoid, the most common autoimmune subepidermal bullous disorder, is associated with autoantibodies targeting antigenic sites clustered within the extracellular domain of BP180. To investigate epitope and subclass specificity of autoantibodies in bullous pemphigoid, we developed an enzyme-linked immunosorbent assay utilizing baculovirus-expressed recombinant forms of the NH2- and COOH-terminal regions of the extracellular domain of BP180 and examined sera obtained from patients with active bullous pemphigoid (n=116) and controls (n=100). Ninety-three (80%) and 54 (47%) of the 116 bullous pemphigoid sera recognized the NH2- and COOH-terminal regions, respectively, of the extracellular domain of BP180. Detailed analysis demonstrates that (i) this novel enzyme-linked immunosorbent assay is highly specific (98%) and sensitive (93%) as 108 of 116 bullous pemphigoid sera reacted with at least one of the baculovirus-derived recombinants, (ii) in active bullous pemphigoid, autoantibodies against the NH2-terminus of the extracellular domain of BP180 were predominantly of the IgG1 class, whereas a dual IgG1 and IgG4 response to this region was related to a more severe skin involvement, (iii) autoreactivity against both the NH2- and COOH-terminal regions was more frequently detected in patients with mucosal lesions, and (iv) levels of IgG (and IgG1) against the NH2-terminal, but not against the COOH-terminal portion of the extracellular domain of BP180, reflected disease severity indicating that autoantibodies against the NH2-terminus are critical in the pathogenesis of bullous pemphigoid. In conclusion, this novel enzyme-linked immunosorbent assay represents a highly sensitive and specific assay for rapid diagnosis of bullous pemphigoid and related disorders and may provide predictive parameters for the management of bullous pemphigoid patients.

Autoantibodies↗
PubMedDate not supplied

Beneficial and detrimental influences of tissue inhibitor of metalloproteinase-1 (TIMP-1) in tumor progression.

Tissue inhibitor of metalloproteinase-1 (TIMP-1) is one representative of the natural matrix metalloproteinase (MMP) inhibitor family, encompassing four members. It inhibits all MMPs, except several MT-MMPs, and a disintegrin with a metalloproteinase domain (ADAM)-10 with Kis < nM. Unexpectedly, its upregulation was associated to poor clinical outcome for several cancer varieties. Such finding might be related to the growth-promoting and survival activities of TIMP-1 for normal and cancer cells. In most cases, such properties are MMP-independent and binding of TIMP-1 to an unknown receptor system can trigger JAK (or FAK)/PI3 kinase/Akt/bad-bclX2 (erythroid, myeloid, epithelial cell lines) or Ras/Raf1/FAK (osteosarcoma cell line) signaling pathways. The relationship between viral infection and TIMP-1 expression is here underlined. Thus, TIMP-1 might display a dual influence on tumor progression; either beneficial by inhibiting MMPs as MMP-9 and by impairing angiogenesis or detrimental by favoring cancer cells growth or survival. We consider that the proMMP-9/TIMP-1 balance is of critical importance in early events of tumor progression, and might show promise as diagnostic and prognostic marker of malignancy.

Angiogenesis Inhibitors↗
PubMedDate not supplied

Chronic infantile neurological, cutaneous, and articular syndrome with severe early articular manifestations.

We report an 11-month-old boy of French origin who had chronic, infantile, neurological, cutaneous, and articular syndrome with a particularly severe joint involvement with early onset. The diagnosis was based on the association of neurologic, cutaneous (urticarial skin eruption), and articular manifestations accompanied by recurrent bouts of fever. No mutation of the CIAS1 gene could be identified. Skeletal involvement was particularly severe, leading to considerable limitation of motion.

Abnormalities, Multiple↗
PubMedDate not supplied

The metalloprotease-directed shedding of BP 180 (collagen XVII) from human keratinocytes in culture is unaffected by ceramide and cell-matrix interaction.

The constitutive shedding of BP180 (collagen XVII) from human keratinocytes in culture was totally prevented by batimastat (5 microM), a wide spectrum matrix metalloprotease (MMP) inhibitor. However, keratinocytes did not express active MMP and generation of active Gelatinase A (MMP-2) and Gelatinase B (MMP-9) at the cell plasma membrane by increasing the ceramide content of keratinocytes did not influence BP180 processing to a 120 kDa species. A disintegrin and metalloprotease (ADAM) is probably involved in such a shedding event since release of 120 kDa polypeptide was inhibited by Decanoyl-Arg-Val-Lys-Arg CH2Cl (30 microM), a specific furin convertase inhibitor; culturing cells on to several matrix substrata i.e. type I collagen, type IV collagen, laminin-1 or laminin-5 had no effect on BP180 processing. Overall our data indicated that the metalloprotease-mediated shedding of BP180 from keratinocytes in culture is insensitive either to agents which activate MAP kinase pathway (ceramide) or to cell-matrix interactions.

Adult↗
PubMedDate not supplied

P16 is overexpressed in cutaneous carcinomas located on sun-exposed areas.

BACKGROUND: Recently, an increased expression of P16, a cell cycle regulatory tumor suppressor protein, has been demonstrated in cervical squamous neoplasms as a marker of malignancy. In contrast, studies performed in skin carcinomas led to contradictory results. OBJECTIVES: Our first aim was to evaluate P16 expression in different types of non-melanoma skin cancers compared with normal skin and benign tumors. The second aim was to evaluate the relationship between P16 expression and the location of skin tumors (i.e. exposed versus non exposed sites). Finally, we also studied Ki67 expression in skin carcinomas and control biopsies. METHODS: Skin biopsy specimens with typical histologic features of squamous cell carcinoma (SCC; n = 30), Bowen's disease (BD; n = 17), basal cell carcinoma (BCC; n = 10), seborrheic keratosis (SK; n = 10) and normal human skin (NHS; n = 9) were obtained from 76 patients seen at our institution between 2001 and 2003. In all cases, P16 and Ki67 expression were evaluated by immunohistochemistry and image analysis. RESULTS: P16 overexpression was observed in 58% of cutaneous carcinomas (SCC: 60%; BD: 58%; BCC: 50%) versus 0% of SK or NHS (0%) (p = 0.006). Ki67 expression in over 5% of tumour cells was observed in 69% of cutaneous carcinomas (SCC: 54%; BD: 76%; BCC: 80%) versus 16% in the group including SK (30%) and NHS (0%) (p = 0.04). Overexpression of P16 was associated with a high rate of Ki67 positive tumour cells in 23/57 malignant skin tumors (40%). Both P16 was associated and Ki-67 were negative in 7/57 cases (12%). Sixty-eight percent of tumors located on sun-exposed areas versus 23% of those located on non sun-exposed areas overexpressed P16 (p = 0.02). CONCLUSION: Our study demonstrated that the expression of P16 and Ki67 is associated with skin carcinomas. No difference was observed according to histological types of carcinomas, suggesting that P16 and Ki67 expression did not correlate with the degree of proliferation and malignancy. Within cutaneous carcinoma specimens, P16 overexpression was significantly associated with the location on sun-exposed areas, suggesting a possible induction of P16 overexpression by UV radiation.

Adult↗