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Biomedical subjects

G E Pierard

Publications and source records attributed to G E Pierard.

16 recordsLinked to original sources
PubMed1992

A comparison of intraperitoneal prostheses for the repair of abdominal muscular wall defects in rats.

We compared the tissue response to the intraperitoneal implantation of three different prostheses (Gore-Tex, Mersilène, Vicryl-Mersilène) used to repair abdominal wall defects in rats. Vicryl-Mersilène is a new experimental prosthesis made of Dacron (Mersilène) coated with absorbable polyglactin (Vicryl). The least amount of adhesions to omentum and gut was found with Mersilène. Gore-Tex was responsible for the accumulation of neutrophils rather than macrophages mostly collected in close contact with Mersilène and Vicryl-Mersilène. Fibrosis, evaluated by histology and computerized morphometry, was mostly found with Vicryl-Mersilène. This should allow a better incorporation of Mersilène and a tighter anchorage to the abdominal wall, after Vicryl resorption.

Abdominal Muscles↗
PubMed1979

Histopathology of remodelling induced by PUVA in the superficial dermis.

The histopathological alterations induced by PUVA within the skin are reported in a patient treated for psoriasis. The main impact is located at the site of former psoriatic plaques in which the target is the microvasculature. A residual coating sheath is present around vessels and fibrosis appears in the superficial dermis. These remodellings interfere with the normal dermo--epidermal relationships; the epidermis contains atypical keratinocytes, and melanocytes are no longer recognizable.

Adult↗
PubMed1979

Phenytoin dependent fibrosis in polyfibromatosis syndrome.

We have followed up the evolution of a polyfibromatosis syndrome in a 20-year-old male treated with diphenylhydantoin for epileptic convulsions. The main symptoms were attributable to fibrosis of the adventitial dermis associated with camptodactyly, knuckle pads, tendinous calcification, osseous hypoplasia of the face, scoliosis with thoracic deformation, and osteolytic changes of wrists, hands and feet. Quantitative variations of the mechanical properties of skin measured in vivo suggested a reversible fibrosing action of diphenylhydantoïn in a genetically predisposed patient.

Adult↗
PubMed1979

Toxic effects of metals from the environment on hair growth and structure.

Diffuse alopecia related to ingestion of toxic metals from the environment has been observed in 36 patients. Copper, arsenic, mercury and cadmium were involved and the intensity of disturbance of the hair cycle, heralded by presence of dystrophic hairs, was proportional to the amount of toxic material detected in blood and urine. Toxicity can be observed in vitro by measuring labeled cells on squash preparations after incorporation of tritiated uridine and thymidine in plucked hairs. The labeling indexes, as well as the ratio between cells entering the S phase and the viable cells were always lower in toxic alopecia than in normal hair. Toxic metals do not seem to affect the morphology of the hair shaft.

Arsenic Poisoning↗
PubMed1979

Cell proliferation in a malignant angioendothelioma during sequential chemotherapy.

The rate of cellular proliferation was studied in the neoplastic cells of a malignant angioendothelioma and in its inflammatory infiltrate by means of optical radioautography after incorporation ex vivo of tritiated thymidine. One third of the normal looking, as well as the atypical, endothelial cells were engaged in the cell cycle of proliferation. This large pool has been effectively suppressed during subsequent chemotherapy which resulted in partial regression of the neoplasm. The proliferative activity of the infiltrate was higher inside the neoplasm than at its periphery.

Aged↗
PubMed1977

Physiopathological variations in the mechanical properties of skin.

An evaluation of the rheological properties of skin is provided by measuring "in situ" the ability of skin to withstand vertical forces of extension. In physiological conditions the biomechanical parameters are reproducible and related to age, sex, skin thickness and the microarchitecture of the connective tissue studied by scanning electron microscopy. These observations shed some light on the structure-function relationship of the fibrous framework of the connective tissue. Variation in the biomechanical parameters can be used to substantiate clinical diagnosis and to monitor the evolution and the therapy of various diseases of the connective tissue.

Adolescent↗
PubMed1977

Traumatic alopecia in trichotillomania: a pathogenic interpretation of histologic lesions in the pilosebaceous unit.

Ten patients with traumatic alopecia (trichotillomania) were being investigated histologically and, in five of them, hairs from the affected scalp area were plucked out for direct microscopic examination. Some histologic features appear to be specific markers for traumatic alopecia: empty hair ducts, plucked out hair bulbs, clefts in hair matrix, catagen involution of empty outer root sheaths, Miescher's trichomalacia in the deep dermis and torn-off sebaceous glands. Other signs are unspecific, such as presence of catagen and anagen VI hairs, infundibular plugging, melanin in keratin plugs and in the dermal papilla. The relative frequency of the different histopathologic features was evaluated. When little clinical information is available, a diagnosis of traumatic alopecia can be supported by skin biopsy. The histologic picture of trichotillomania is always incomplete, depending upon factors such as intensity of pulling or/and time of biopsy after plucking.

Alopecia↗
PubMed1977

Interaction between collagen type I and type III in conditioning bundles organization.

Type I and type III collagen extracted from skin was purified by differential salt precipitation and chromatography. By heating to 37 degrees, type I formed after a lag phase a floppy and opalescent gel of high optical density and type III formed more rapidly a translucent and rigid gel of low optical density. Addition of type III to type I resulted in formation of gels of reduced optical density and lag phase related to the proportion of type III added. Phase contrast and scanning electronmicroscopy demonstrated the formation of thick bundles of type I, thin fibers of type III and bundles of intermediate size related to the proportion of type III. The relationship between collagen type and bundle architecture might prove most significant in conditioning the mechanical properties of the connective tissues in normal and pathological conditions.

Amino Acids↗
PubMed1976

Cell renewal in discoid lupus erythematosus.

Cell proliferation has been evaluated in four patients with discoid lupus erythematosus after in vivo incorporation of tritiated thymidine. Numerous epidermal cells are in S phase or in mitosis. The acceleration of cell renewal is paralleled by a shortening of the transit time of completely differentiating keratinocytes. Remodellings of the vascular belt are evidenced by the labeling of many endothelial cells. There is no sign of lymphoblastic transformation in the dermis since the mononuclear infiltrate remains unlabeled.

Adult↗
PubMed1975

Cellular activity in the dermis surrounding the hair bulb in alopecia areata.

The metabolic activity of the cells in the connective tissue surrounding the hair bulb has been studied by radioautography in alopecia areata and in normal scalp, using in vitro incorporation of tritiated thymidine, uridine, histidine, leucine and proline. In alopecia areata, the hair bulbs are blocked in the anagen IV stage and DNA, RNA and protein synthesis are restrained. Cells in the papilla, as well as the cellular infiltrate, display a very low rate of metabolic activity. During regrowth in alopecia areata, the activity of endothelial cells is increased in the papillary and peribulbar layers before DNA, RNA and protein synthesis are restored in the epithelial cells of the hair bulb. The dermal and epithelial labelling patterns eventually reach levels comparable to those observed in an induced anagen IV state of a normal scalp. It is concluded that the progression from anagen IV to a further stage represents a critical period in the growth of hair that would closely depend upon an adequate metabolic function of the connective tissue. It is impaired in alopecia areata.

Alopecia Areata↗
PubMed1975

Modulation of dermal cell activity during hair growth in the rat.

Interaction between connective tissue cells and hair growth in the rat has been studied by radioautography after in vivo and in vitro pulse labelling with thymidine, uridine, histidine, leucine and proline. The connective tissue, which surrounds and integrates the hair bulbs as a unit, contains cells of various types which have a cyclic metabolic activity. This cyclic activity is coordinated with the hair growth cycle. The number of nuclei which actively synthesize DNA in the dermal cells, mainly those of endothelial and migratory cells, significantly increases during the short and transient anagen 4 substage. RNA and protein synthesizing activities are also present in all cell types and seem modulated by the hair cycle although to a lesser degree. This data provides an important basis for the interpretation of similar studies in alopecia areata.

Animals↗
PubMed1975

[Structure and pathogenic interpretation. Acquired dystrophies of the hair].

The size and form of a segment of a hair are two relatively constant parameters. Their homeostasis reflects precise regulation of the size and form of the matrix (therefore of the papilla), of the proportion of cells normally involved in the cycle of cell division and of the duration of this cycle and of the increase in the average volume of cells during differentiation. Any disturbance in this precise pattern causes dystrophies. Some of these acquired abnormalities in hair structure have been examined by scanning electron microscopy. Two malformations arising from indentation of the papilla were compared: pili gemini and pagothrix. Their cuticular organisation does not appear to be impaired and remains independent of the fusion and separation of the hair shafts. In addition to these dystrophies due to abnormal formation of the matrix, there are other malformations, bayonet hair and the Pohl-Beau line, which are secondary to temporary disturbances in other volumetric control parameters. Their pathogeny appears similar and their varying aspect is the result of graduated cellular response to the inductor. The structure of the cuticlar of these hairs varies according to their volume: a narrow segment shows a corresponding decrease in the free surface of the cuticular cells; on the other hand, an increase in the volume of the hair causes less overlapping of cuticle cells. The hair generally breaks where there is constriction. These fractures are transversal due to concentration of normal constraint and resemble trichoclasia or trichoschisis in normal or peladic hair. They never occur in the form of a trichoptilosis affecting normal or permed hair.

Hair↗