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Biomedical subjects

G Duport

Publications and source records attributed to G Duport.

At least 19 recordsLinked to original sources
PubMed2005

[Four-layer laryngotracheoplasty to repair an anterior tracheal wall defect induced by a Montgomery T-tube].

A 37-year old patient was referred in 2000 for reconstruction of the anterior tracheal wall eroded by a Montgomery T-tube. A four-layer laryngotracheoplasty was proposed to the patient. The endotracheal plane was reconstructed by a bilateral random pattern quadrangular skin hinge flap raised from both sides of the defect. The chondral plane was realized with conchal cartilage. This cartilage graft was covered with an inferiorly based sternocleidomastoid flap. The fourth layer was a mesh split-thickness skin graft. Satisfactory and lasting results were observed during a three-year follow-up. Few articles deal specifically with tracheal reconstruction after anterior wall erosion induced by a Montgomery-T tube. We found no mention of the described four-layer flap in the literature.

Adult↗
PubMed2005

Effects of plant protease inhibitors, oryzacystatin I and soybean Bowman-Birk inhibitor, on the aphid Macrosiphum euphorbiae (Homoptera, Aphididae) and its parasitoid Aphelinus abdominalis (Hymenoptera, Aphelinidae).

Transgenic plants expressing protease inhibitors (PIs) have emerged in recent years as an alternative strategy for pest control. Beneficial insects such as parasitoids may therefore be exposed to these entomotoxins either via the host or by direct exposure to the plant itself. With the objective of assessing the effects of PIs towards aphid parasitoids, bioassays using soybean Bowman-Birk inhibitor (SbBBI) or oryzacystatin I (OCI) on artificial diet were performed on Macrosiphum euphorbiae-Aphelinus abdominalis system. OCI significantly reduced nymphal survival of the potato aphid M. euphorbiae and prevented aphids from reproducing. This negative effect was much more pronounced than with other aphid species. On the contrary, SbBBI did not affect nymphal viability but significantly altered adult demographic parameters. Enzymatic inhibition assays showed that digestive proteolytic activity of larvae and adults of Aphelinus abdominalis predominantly relies on serine proteases and especially on chymotrypsin-like activity. Immunoassays suggested that OCI bound to aphid proteins and accumulated in aphid tissues, whereas SbBBI remained unbound in the gut. Bioassays using M. euphorbiae reared on artificial diets supplemented with both OCI and SbBBI showed a fitness impairment of Aphelinus abdominalis that developed on intoxicated aphids. However, only SbBBI was detected in parasitoid larvae, while no PI could be detected in adult parasitoids that emerged from PI-intoxicated aphids. The potential impact of PI-expressing plants on aphid parasitoids and their combined efficiency for aphid control are discussed.

Animals↗
PubMed2001

Calcium currents and transients in co-cultured contracting normal and Duchenne muscular dystrophy human myotubes.

1. The goal of the present study was to investigate differences in calcium movements between normal and Duchenne muscular dystrophy (DMD) human contracting myotubes co-cultured with explants of rat spinal cord with attached dorsal root ganglia. Membrane potential, variations of intracellular calcium concentration and T- and L-type calcium currents were recorded. Further, a descriptive and quantitative study by electron microscopy of the ultrastructure of the co-cultures was carried out. 2. The resting membrane potential was slightly less negative in DMD (-61.4 +/- 1.1 mV) than in normal myotubes (-65.5 +/- 0.9 mV). Both types of myotube displayed spontaneous action potentials (mean firing frequency, 0.42 and 0.16 Hz, respectively), which triggered spontaneous calcium transients measured with Indo-1. 3. The time integral under the spontaneous Ca(2+) transients was significantly greater in DMD myotubes (97 +/- 8 nM s) than in normal myotubes (67 +/- 13 nM s). 4. The L- and T-type current densities estimated from patch-clamp recordings were smaller in DMD cells (2.0 +/- 0.5 and 0.90 +/- 0.19 pA pF(-1), respectively) than in normal cells (3.9 +/- 0.7 and 1.39 +/- 0.30 pA pF(-1), respectively). 5. The voltage-dependent inactivation relationships revealed a shift in the conditioning potential at which inactivation is half-maximal (V(h,0.5)) of the T- and L-type currents towards less negative potentials, from -72.1 +/- 0.7 and -53.7 +/- 1.5 mV in normal cells to -61.9 +/- 1.4 and -29.2 +/- 1.4 mV in DMD cells, respectively. 6. Both descriptive and quantitative studies by electron microscopy suggested a more advanced development of DMD myotubes as compared to normal ones. This conclusion was supported by the significantly larger capacitance of the DMD myotubes (408 +/- 45 pF) than of the normal myotubes (299 +/- 34 pF) of the same apparent size. 7. Taken together, these results show that differences in T- and L-type calcium currents between normal and DMD myotubes cannot simply explain all observed alterations in calcium homeostasis in DMD myotubes, thus suggesting that other transmembrane calcium transport mechanisms must also be altered in DMD myotubes compared with normal myotubes.

Animals↗
PubMed2001

Cationic channels in normal and dystrophic human myotubes.

Human skeletal muscle cells obtained from normal and Duchenne muscular dystrophy patients were cocultured with explants of rat dorsal root ganglions. Single-channel recordings were performed with the cell-attached configuration of the patch-clamp technique and negative pressure was applied via the patch-pipette in order to mechanically stimulate the membrane patch. Inward elementary current activity was recorded under control or negative pressure conditions. Its occurrence and mean open probability were higher in Duchenne muscular dystrophy. Amplitude histograms reveal that these channels have a small unitary conductance of around 10 pS in 110 mM Ca2+ and could be inhibited in a dose-dependent manner by gadolinium. Results show that the membrane stress favoured calcium permeation through these channels. Taken together these data provide arguments for the involvement of such channels in calcium overload previously observed in cocultured dystrophic human (Duchenne muscular dystrophy) muscle cells.

Animals↗
PubMed2001

[Pigmented Paget's disease of the male nipple].

BACKGROUND: Mammary Paget's disease unfrequently occurs in males, and may be pigmented in rare instances. Differential diagnosis with malignant melanoma relies on immunohistochemical studies. CASE REPORT: A case of Paget's disease of the nipple in a 76 year-old male is reported, clinically mimicking a malignant melanoma because of massive pigmentation. Histologically, large Paget's clear cells were intermingled with numerous melanin-rich dendritic melanocytes. An underlying ductal carcinoma was found. After differential immunohistochemical staining, diagnosis of Paget's disease could be unequivocally substantiated since Paget's cells stained for epithelial markers, c-erbB-2 and hormonal receptors, whereas protein S100 and HMB45 were negative. DISCUSSION: Pigmentation in mammary Paget's disease occurs preferentially in males. Pigmentation results from numerous melanocytes with abundant melanin in close contact with Paget's cells. An increased number of melanocytes may also be observed in cutaneous metastatic breast carcinomas. It could result from a chemotactic factor produced by neoplastic cells.

Aged↗
PubMed2001

[Mixed type amyloidomas, beta2 microglobulin and AL lambda, in a long term hemodialysis patient].

A frequent complication of hemodialysis is deposition of beta 2-microglobulin amyloid in tendons and joints. Soft tissues involvement is exceptional. A 74 year-old woman on hemodialysis for 21 years developed two bilateral and symmetric tumours in gluteal regions causing discomfort when sitting. Histology, immunohistochemistry and electron microscopy showed that deposit consisted of predominant beta 2-microglobulin and lambda light chain. This is an unusual localisation of amyloidosis developing late in the course of hemodialysis. It may be perhaps initiated by chronic traumatism and be promoted by the light chain lambda of immunoglobulin.

Adipose Tissue↗
PubMed2000

[Malignant melanoma in the child: an uncommon illness].

BACKGROUND: Malignant melanoma are uncommon in children and are sometimes difficult to distinguish from Spitz nevi. Histological diagnosis is particularly difficult. CASE REPORT: Three prepuberty children (aged 14, 10 and 14 years) underwent excision of suspicious nevi found at pathology examination to be malignant melanomas. After complementary treatment the recurrence-free survival has been 18, 14 and 4 years respectively. DISCUSSION: Clinical signs of malignant melanomas are unspecific. As in adults, any modification in a melanic lesion should led to excision and pathology examination. In the literature, there is often a confusion between malignant melanoma developing in children and young adults making it difficult to determine the prognosis of the childhood disease. Prognosis of cutaneous malignant melanomas is generally good (excluding giant nevi and congenital malignant melanoma).

Adolescent↗
PubMed1999

The effect of methylprednisolone on intracellular calcium of normal and dystrophic human skeletal muscle cells.

Clinical trials have shown that a glucocorticoid, the methyiprednisolone (PDN), has a beneficial effect on muscle strength and function in Duchenne muscular dystrophy (DMD) patients. The aim of this study was to test if the effect of PDN could be mediated via a possible action on intracellular calcium. The intracellular calcium activity, at rest and during calcium mobilizing drug superfusion protocols was recorded in normal and dystrophic human cocultured muscle cells. PDN (10 microM) pretreatment induced an elevation of the resting calcium concentration of 51, 34 and 38% in proliferating normal myoblasts, DMD myoblasts and DMD myotubes, respectively, while normal myotubes resting [Ca2+]i was not altered.

Adolescent↗
PubMed1998

[Approach to severe functional deficiencies: evaluating the efficacy of a special multidisciplinary consultation].

A global approach is required to evaluate severe functional deficits. We have developed a multidisciplinary consultation and assessed its usefulness after one year. A total of 62 patients were evaluated (mean age 35 years), usually for neurological functional deficit (50%). Among the 62 patients, surgery was proposed in 72.6% (operations performed in 66%). Others were managed with non-surgical procedures or abstention. The functional outcome as assessed by patients and physicians was poor (or no result) for 6%, fair for 15%, good or very good for 79%. These results suggest that such a multidisciplinary approach is worth being pursued. Some adjustments for psychological dysfunction may further improve outcomes.

Adolescent↗
PubMed1998

Malignant blue nevus: three new cases and a review of the literature.

Three patients with malignant blue nevus are reported-one on the right side of the body, one on the right arm, and one on the face. The criteria and difficulty of histopathological diagnosis are considered as well as the differential diagnoses for this tumor. The therapy is described, and the possible relations between malignant blue nevus and certain other tumors (e.g., atypical or locally aggressive cellular blue nevus) are explored. A review of the literature reveals that there is current disagreement about the exact prognosis for these tumors and indicates the need to collect data for all patients observed.

Adult↗
PubMed1997

Obtaining maximal use of expanded scalp rotation flaps via an experimental model.

The relative inelasticity of scalp skin and the irregular convexity of the cranial vault necessitate careful planning in the design and mobilization of scalp flaps. Rotation flaps adapt particularly well to the curves of the cranial vault. An experimental model has enabled us to study the design and mobilization of expanded scalp rotation flaps and to obtain maximal efficiency from the tissue expansion process. The use of a round tissue expander situated immediately adjacent to a scalp defect is an excellent method for the creation of a rotation flap. To optimize the use of the expanded tissues, the flap should be designed so that its border passes along the periphery of these expanded tissues. In cases in which it is advisable to separate the expander from the defect, such as when the defect is highly contaminated, efficient use of the expanded tissues can still be obtained by placing the expander at the site of a rotation flap backcut. Furthermore, although this study focuses on rotation flaps only, this same model can be used to examine and compare different closure methods using other types of flaps as well.

Child, Preschool↗
PubMed1997

[Evaluating the efficacy of a multidisciplinary approach of severe functional deficits].

Therapeutic indications aimed at improving function in handicapped persons are difficult to establish as the expected result of a given technique may vary. We have developed a multidisiplinary approach for handicapped persons. Our assessment of this activity which has concerned 62 patients from October 1995 to October 1996 is promising and encourages us to continue this type of attitude. Forty-six of the 58 persons evaluated stated they were well satisfied or very well satisfied with the management of their case and outcome was worse in none of the patients.

Adolescent↗
PubMed1997

[Hemifacial atrophy. A case report associated with linear scleroderma].

The authors report a case of facial hemiatrophy, secondary to linear scleroderma, and review the various possible causes of facial hemiatrophy. The various treatments proposed to correct facial hemiatrophy are described. The advantages and disadvantages of each technique together with their indications as a function of the severity of the lesions are then discussed. Free flap currently appears to be the treatment of choice in severe forms and the main question concerns the choice of flap. The authors prefer an inverted dermal fat flap because of its advantages (absence of long-term ptosis, better facial contours) and the absence of laparotomy.

Adolescent↗
PubMed1996

Hypoosmotic shocks induce elevation of resting calcium level in Duchenne muscular dystrophy myotubes contracting in vitro.

In Duchenne muscular dystrophy (DMD) muscle cells which lack dystrophin, contraction seems to be a dominant factor contributing to the abnormal elevated intracellular calcium level. Human normal and DMD contracting myotubes cocultured with nervous cells were exposed to a hypotonic medium to mimic contraction-induced mechanical stress on the membrane, and the cytoplasmic calcium activity was simultaneously monitored (Indo-1). Hypotonic shocks induced a reversible [Ca2+]i increase in 81% of the DMD cells vs. 54% of control. In addition, responses were qualitatively different: most of DMD myotubes displayed a fast increase of Ca2+ flowing from the edge of the myotube while the response in normal cells was slow and diffuse. The fact that these responses were not affected by ryanodine, was in favour of an external source of Ca2+ involved in the hypoosmotic shocks. The localized increase of Ca2+ in DMD myotubes, inhibited by Gd3+, could result from sites of high mechanosensitive channel activity or density which could constitute a pathway for Ca2+ entry provided these cells contract.

Calcium↗
PubMed1996

[Lesions of the hand and upper limb in children with linear scleroderma. Therapeutic approach in two cases].

The authors report two cases of linear scleroderma (LS) in children, located on the hand and upper limb. LS is rare in children (245 cases reported in the literature). LS initially consists of a sclero-inflammatory lesion, followed by a sclero-atrophic lesion, characterized by its linear arrangement selective involvement of one limb, and its local and regional effects. The onset is generally marked by development of a sclerodermic line, sometimes associated with extra-cutaneous lesions. The active phase of the disease is long (mean: 3 years), with multiplication or extension of the initial lesions (frontal "coup de sabre", hemiatrophy). Systemic complications are rare (Raynaud's phenomenon, glomerulonephritis...). Regional complications (retractile myositis, articular stiffness, shortening) are frequent, severe and persistent (75% of cases). Treatment has not been definitively standardized, but should include:--systemic corticosteroids, quite active in early forms. --physiotherapy and external prostheses during the early and active phase, and finally surgical correction of orthopaedic sequelae. They are often difficult operations, with partial results, but functionally very useful, especially with the addition of cutaneous expansion. Our 2 cases demonstrate the considerable functional improvement achieved in the hand.

Adrenal Cortex Hormones↗
PubMed1996

In-vitro biomechanical study of a dorso-lumbo-sacral posterior supple instrumentation with variable section.

This study is designed to analyse the behavior, in the sagittal plane, of a complete human dorso-lumbar rachis, made rigid by the posterior instrumentation used for the treatment of scoliosis, on subjects suffering from DMD (Duchenne Muscular Dystrophy). The object of this analysis is to demonstrate the reliability of early surgery made possible by new instrumentation. Close review of the literature shows that the currently used Harrington or Luque instrumentations lead to mechanical complications, especially rod breaking, at the thoraco-lumbar junction. 8 specimens were non-destructively tested in-vitro. Compression and flexion were applied. For each test, rachis movements with and then without instrumentation, and also rod restraints were noted. The results show a linear stiffness multiplied by 8.3 in flexion and 11.6 in extension. The maximum restraint recorded for physiological displacements is 77 MPa. This remains largely under the fatigue-breaking limit of the metal used (stainless steel hammer-hardened 316 L, Young's modulus = 200,000 MPa, Poisson's ratio = 0.21, endurance limit = 350 MPa at 5 x 10(6) cycles). The results of this study encourage us to continue and develop early surgery in children affected by myopathy, with fixation of the complete rachis, including a lumbo-sacral arthrodesis and a supple dorsal part of the mounting, in the sagittal plane.

Aged↗