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Biomedical subjects

H Dumas

Publications and source records attributed to H Dumas.

7 recordsLinked to original sources
PubMed2004

[Post mortem brain MRI: an alternative for pathology examination in Bourneville tuberous sclerosis of the fetus?].

Antenatal discovery of cardiac rhabdomyomes evokes the diagnosis of Bourneville's disease. Antenatal brain exploration with ultrasonography and magnetic resonance imaging (MRI) can highlight cerebral localizations. In the event of termination of pregnancy, confirmation of the cerebral lesions can be achieved with post mortem MRI as well as pathology examination. MRI can be usefully employed in the event pathology examination is not feasible.

Adult↗
PubMed2001

Aquatic therapy in pediatrics: annotated bibliography.

"Aquatic therapy" refers to therapeutic intervention taking place in water. The purpose of this review is to summarize the published articles in the rehabilitation literature from 1979 through 1999 that relate to the use of aquatic therapy as an intervention for children and adolescents with neuromuscular and musculoskeletal diagnoses. Despite the trend toward evidence-based practice, a paucity of literature exists related to aquatic therapy for children. Most of the available articles are case reports and other descriptions of clinical practice. The research reports are limited in design and scope, and subjects had a wide variety of ages and diagnoses.

Exercise Therapy↗
PubMed1991

In vitro and post-transplantation differentiation of human keratinocytes grown on the human type IV collagen film of a bilayered dermal substitute.

Using human type IV and type I + III collagens and a new, nontoxic cross-linking procedure, we have developed a cell-free bilayered human dermal substitute for organotypic culture and transplantation of human skin keratinocytes. We have studied the formation of the basement membrane, and the differentiation of keratinocytes grown on the type IV collagen layer of this dermal substitute, in vitro and after grafting onto nude mice. These studies demonstrated the formation of essential constituents of the basement membrane in culture: hemidesmosomes and deposition of extracellular matrix on the top of the type IV collagen were observed as early as 6 days after plating of human keratinocytes. Although the keratinocytes formed a well-organized multilayered epithelium, they exhibited limited differentiation when grown submerged in liquid medium. However, the multilayered sheet obtained after 14 days in submerged culture was composed of a regular basal cell layer, several nucleated suprabasal cell layers containing granular cells, and several dense, anucleated cell layers. The grafting experiments have shown a good biocompatibility of the dermal substitute. It is repopulated by fibroblasts, newly synthesized collagen, vessels, and a few mononuclear cells. At Day 14 after grafting, the type IV collagen layer was still present and very dense, and the basement membrane appeared as in culture, with numerous well-structured hemidesmosomes and deposition of extracellular matrix resembling lamina densa. At Day 55 after transplantation, even if the epidermal graft did not exhibit all the characteristics of the normal epidermis in vivo, it was very close to it. At this stage, the basement membrane was complete, with structures clearly indicative of anchoring fibrils. This new dermal substitute offers many advantages. It is stable and easy to handle. Its production is standardized. The oxidation induced by periodic acid led to a nontoxic cross-linked matrix. This dermal substitute is the first one entirely composed of human collagens. The type I + III collagen underlayer is reorganized when grafted. It supports a type IV collagen top layer which offers an excellent substrate for keratinocytes, favors their anchorage, and favors the formation of the basement membrane in vitro. This dermal substitute could be useful for wound coverage or as an in vitro model for toxicological and pharmacological studies.

Basement Membrane↗
PubMed1990

Fibroblast behavior on gels of type I, III, and IV human placental collagens.

Various collagens were extracted and purified from human placenta after partial pepsin digestion. We prepared type III + I (57:43), enriched type I, type III, and type IV collagens on an industrial level, and studied their biological properties with MRC5 fibroblast cells. Using the process of contraction of a hydrated collagen lattice described by Bell, we found tha the contraction rate was dependent on collagen type composition. The contraction was faster and more pronounced with pepsinized type I collagen than with pepsinized type III + I (57:43) collagen; the lowest rate was obtained with the pepsinized type III collagen. Using a new technique of collagen cross-linking, a gel was made with type IV collagen. This cross-linking procedure, based on partial oxidation of sugar residues and hydroxylysine by periodic acid, followed by neutralization, resulted in an increased number of natural cross-link bridges between oxidized and nonoxidized collagen molecules, without internal toxic residues. The fibroblasts were unable to contract type IV/IVox collagen gels. The type IV/IVox collagen gel was transparent and its amorphous ultrastructure lacked any visible striated fibrils. Fibroblast cells exhibited atypical behavior in these type IV/IVox collagen gels as evidenced by optical and electron microscopy. The penetration of fibroblasts could be measured. Fibroblasts penetrated faster in type IV/IVox collagen gels than in untreated type III + I collagen gels. The lowest rate of penetration was obtained with cross-linked type III + I gels. Fibroblast proliferation was similar on untreated or cross-linked type III + I collagen gels and slightly increased on type IV/IVox collagen gels, suggesting that this cross-linking procedure was not toxic.

Cell Division↗
PubMedDate not supplied

[Collagen and its technological possibilities].

Collagen enjoys a privileged position as a biomaterial in its cosmetic applications. It exists under different forms and is more particularly able to reticulate. The process which is used allows a modulated reticulation. This means that a collagenous matrix having a varying degree of solubility can be obtained, which can lend itself to different applications. The prilling technique consists in producing microspheres consisting of a more or less reticulated collagenous matrix being able or not to imprison an insoluble or lipophilic active substance having previously been incorporated in the original solution. In this way, it is possible to obtain either strongly reticulated and mechanically resistant microspheres of particles which dissolve when crushed. The cosmetic significance of these new products is connected with the biocompatibility characteristics of the collagenous material and with the characteristics relating to the modulated reticulation of the obtained product.

Collagen↗