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Biomedical subjects

C Lebreton

Publications and source records attributed to C Lebreton.

At least 19 recordsLinked to original sources
PubMed1991

[Magnetic resonance imaging of fluorosis and stress fractures due to fluoride].

Osteocondensation of the spine and stress fractures of the appendicular bones are observed under treatment with sodium fluoride or after long-term drinking of Vichy Saint-Yorre spring water. Five patients with a mean total dose of fluoride intake of 24.7 g (9-66) were studied with MR imaging. Two of them had a diffuse osteocondensation; MRI showed a low signal intensity in the vertebrae on T1 and T2-weighted images. MRI was performed in an asymptomatic patient who was being treated with sodium fluoride for 16 months; it revealed a heterogenous low signal intensity in the pelvis and femoral metaphysis. Two patients experienced stress fractures; MRI demonstrated a linear area of very low signal intensity surrounded by an area of decreased signal intensity on T1-weighted images and high signal intensity on T2-weighted images. MRI of fluorosis shows a non specific low signal intensity linked to a densifying image on the standard radiograph or an area of high technetium-99m intake on bone scan.

Aged↗
PubMed1990

Human dermal fibroblasts modulate the effects of retinoids on epidermal growth.

We report the pharmacologic effects of retinoids in a human skin-equivalent model. This sophisticated culture system is composed, as in vivo, of a dermis and epidermis, and provides a unique in vitro system for studying dermal-epidermal interactions and thus, whether normal dermal fibroblasts influence the effects of retinoids on epidermal growth. Epidermalization was initiated on collagen substrates in which fibroblasts were either viable or lysed by osmotic shock. Retinoic acid, isotretinoin, and acitretin at 10(-6) M or 10(-7) M were added to the cultures just after epidermalization, then every two days. Epidermal growth was determined after 2 weeks in terms of the surface area, DNA content, and tritiated thymidine incorporation during the last 24 h of culture. In the absence of viable fibroblasts, retinoic acid and isotretinoin increased epidermal growth, whereas etretin inhibited it. In contrast, in the presence of viable fibroblasts, retinoic acid and isotretinoin inhibited epidermal growth, whereas etretin had no effect. Thus, retinoic acid and isotretinoin had a similar effect on keratinocyte proliferation that contrasted with that of etretin. Taken as a whole, these results show that fibroblasts, present within a collagen substrate, can modulate the pharmacologic effects of retinoids on epidermal growth.

Adult↗
PubMed1990

[Semi-invasive aspergillosis with involvement of the thoracic wall cured by itraconazole].

Pulmonary aspergillosis invading the thoracic wall is rare and of sombre prognosis. We report the case of a 49-year old man who developed a pulmonary aspergilloma some time after lung resection and radiotherapy for bronchial adenocarcinoma. Surgical excision of the aspergilloma was followed by sternal, then costal aspergillosis. Conventional surgery and antifungal therapy failed, and the lesion stubbornly followed a chronic course until itraconazole therapy was instituted, resulting in a complete cure which still persists nearly 4 years after withdrawal of any chemotherapy.

Antifungal Agents↗
PubMed1990

[Stimulation of epidermal growth in equivalent skin by tissue inhibitor of metalloproteases].

Tissue inhibitor of metalloproteases (TIMP) is a major regulator of extracellular matrix synthesis and degradation. Moreover elevated tissue inhibitor of metalloproteases levels are found in the blister fluid of many diseases, suggesting that tissue inhibitor of metalloproteases plays a role in epidermal and dermal wound healing. The aim of this work was to study the effects of human recombinant tissue inhibitor of metalloproteases in a skin equivalent model used to evaluate the effects of drugs on epidermal and dermal components. Planimetry, DNA assays, and histologic studies showed that tissue inhibitor of metalloproteases enhanced the growth of normal human keratinocytes on dermal equivalent. Thus, the extracellular matrix regulator tissue inhibitor of metalloproteases also stimulates the growth of keratinocytes. Identity of the gene encoding tissue inhibitor of metalloproteases and Erythroid Potentiating Activity (EPA) has been reported. The effects of tissue inhibitor of metalloproteases on keratinocytes described herein are reminiscent of the stimulating effect of erythroid potentiating activity on the growth of erythroid precursors.

DNA↗
PubMed1989

Influence of human dermal fibroblasts on epidermalization.

Using a method that allowed the reconstruction of simplified living human skin in vitro, we investigated the effects of collagen texture and dermal fibroblasts on epidermal growth. Like in vivo skin, our in vitro model comprised two tissues: a dermal equivalent and an overlying epidermis. It permitted measurement of epidermal growth and therefore evaluation of the effect of the dermal equivalent on this growth. Epidermal growth was enhanced when the collagen matrix had previously been reorganized by fibroblasts, and was greatest when living fibroblasts persisted in this matrix. On cell-free collagen gel and on collagen matrices containing dead fibroblasts, epidermal growth increased when the medium was conditioned by fibroblasts grown in monolayers. We conclude that the function of the fibroblasts is not only to synthesize and degrade the extracellular matrix, but also to regulate epidermalization; on the one hand by remodeling the collagen fibers, and on the other by secreting diffusible factors that promote epidermal growth. These results underline the importance of fibroblasts in dermo-epidermal interactions, and show that the skin equivalent culture model provides a way to quantitatively study these interactions.

Adult↗
PubMed1989

Rapid localization of carbon 14-labeled molecules in biological samples by ion mass microscopy.

We report here on the ability of secondary ion mass spectrometry (SIMS) to provide rapid imaging of the intracellular distribution of 14C-labeled molecules. The validity of this method, using mass discrimination of carbon 14 atoms, was assessed by imaging the distribution of two molecules of well-known metabolism, [14C]-thymidine and [14C]-uridine, incorporated by human fibroblasts in culture. As expected, 14C ion images showed the presence of [14C]-thymidine in the nucleus of dividing cells, whereas [14C]-uridine was present in the cytoplasm as well as the nucleus of all cells, with a large concentration in the nucleoli. The time required to obtain the distribution images with the SMI 300 microscope was less than 6 min, whereas microautoradiography, the classical method for mapping the tissue distribution of 14C-labeled molecules, usually requires exposure times of several months. Secondary ion mass spectrometry using in situ mass discrimination is proposed here as a very sensitive method which permits rapid imaging of the subcellular distribution of molecules labeled with carbon 14.

Carbon Radioisotopes↗
PubMed1989

[Desmoid tumors of the mesentery in Gardner's syndrome. Value of x-ray computed tomography].

3 cases of desmoid tumours of the mesentery occurring as part of Gardner's syndrome are reported. In 2 cases, CAT scanning was carried out. We underline the value of this examination compared to other imaging methods. It allows the establishment of a diagnosis, investigation for complications, the operability to be assessed and is useful for monitoring patients. Its major value is in avoiding an unnecessary laparotomy, a factor certain to produce recurrence, in certain patients. Other alternative therapy may then be proposed.

Adult↗
PubMed1987

[Functions of neutrophils in vivo on the human skin. Applications to the study of psoriasis and anti-inflammatory agents].

A reproducible method for sequential study of migration out of human skin, phagocytosis and bactericidal activity of neutrophils is described. Untreated psoriatics exhibit an early increase of chemotactic activity (0-8 h, p less than 0.02) and subsequently a strong inhibition of chemotaxis (8-24 h, p less than 0.01), a slight decrease of phagocytosis and a decrease in bactericidal activity (20 mn, p less than 0.02; 30 mn, p less than 0.003); 60 mn, p less than 0.001; 120 mn, p less than 0.001) as compared with controls. After clearing of skin lesions, the early increased chemotactic activity returned to normal values but the subsequent chemotactic inhibition remains as strong as before treatment. Phagocytosis increased to normal values (p less than 0.02) and bactericidal activity also increased but remained significantly low. The abnormalities were more evident in migrating than in circulating neutrophils, underlining the sensitivity of the described method. Using the same method we have shown that the aromatic retinoid etretinate (Ro 10-9359) and its main metabolite (Ro 10-1670) significantly inhibit the migration of neutrophils from the blood to tissues when applied into skin chambers (0.1 mg/ml) or when given orally (1 mg/kg/day) for 8 days to normal volunteers. This pharmacological property could be closely linked to the antipsoriatic properties of these drugs.

Adult↗
PubMed1987

[Sclerodermatomyositis. Apropos of 13 cases].

13 cases of sclero (dermato)myositis are reported with cutaneous signs specific of dermatomyositis in 6 cases. Scleroderma was rather benign, without any visceral involvement. In contrast, myositis was much more severe that usually encountered in systemic sclerosis, threatening the vital prognosis and requiring aggressive therapeutic measures to be controlled. In 6 cases, the axial musculature was involved. Occurrence of each component was not simultaneous. No case was paraneoplastic. Antinuclear antibodies were present in all cases. Antibodies against soluble nuclear antigens, specifically found by others in sclerodermatomyositis, were absent. The very peculiar clinical spectrum of this syndrome associated with immunologic abnormalities, elsewhere described, confirm the individualization of sclerodermatomyositis.

Adult↗
PubMed1986

A new method for studying epidermalization in vitro.

A new method for studying epidermalization in vitro is described. It consists of inserting a punch biopsy that serves as a source of epidermis into dermal equivalent freshly made up, with fibroblasts mixed in a collagen matrix. Fibroblasts cling to collagen fibrils and contract the matrix, leading in 3 days to a resistant dermal equivalent holding the punch biopsy firmly in place. At day 5, a culture medium favouring epidermal growth was used and a fringe of a new epidermis appeared around the punch, the area of which grew linearly with time. This new epidermis showed a pattern of differentiation similar to epidermis in vivo, with cuboidal basal cells, keratohyalin granules, membrane coating granules and the expression of the 65-67 kd keratin subset. The method seems to combine the advantages of the explant technique and of classical keratinocyte cultures, providing the researcher with a large quantity of differentiated epidermis, the pharmacologist with simple and quantitative system in which to study modifications of growth and differentiation of epidermis, and the plastic surgeon with a possible material for skin grafting.

Biopsy↗
PubMed1986

[Pulmonary digital subtraction angiography. A comparative study of 2 technics. Electrocardiographic servo-assistance versus 3 images per second].

A prospective study in 60 consecutive patients evaluated gain in quality of image using ECG servo-assistance during pulmonary digital subtraction angiography (PDSA). Two groups of 30 comparable patients were randomly allocated to examination with ECG servo-assistance or three images per second technique. Criteria for assessment of quality of image were defined and used to compare results. No significant difference were noted and ECG servo-assistance failed to improve images during PDSA.

Adolescent↗
PubMed1986

[Plication of the hip synovium above the femur neck].

A 23 year old man, expert in karate, complained of sudden movements of right hip during "circular kicks", followed by persistent pain. Arthrography showed synovial plication in joint at upper border femoral neck, with a tongue-like projection from upper recess extending to head/neck junction and provoking bone erosion visible on standard images. Recovery followed resection of the fold. This is probably the first case of this type to be published. The lesion recalls the internal synovial plica of knee but differs from "frenula capsulae" and does not appear to have been described by anatomists. As in the knee it is probably an embryonic relic.

Adult↗
PubMed1985

Psoriatic fibroblasts induce hyperproliferation of normal keratinocytes in a skin equivalent model in vitro.

A skin equivalent model has been used to fabricate tissues with psoriatic and normal cells. Psoriatic fibroblasts can induce hyperproliferative activity in normal keratinocytes. The psoriatic epidermis from lesions continues to proliferate at high rates for at least 15 days in this model, and normal fibroblasts are unable to suppress this hyperproliferation. The primary defect in psoriatic skin may reside in the dermal fibroblast.

Adult↗