Search PubMed⌕ Search

Biomedical subjects

P Poirier

Publications and source records attributed to P Poirier.

49 records · Page 3Linked to original sources
PubMed1995

[Filling of bone defects using biphasic macroporous calcium phosphate ceramic. Apropos of 23 cases].

PURPOSE OF THE STUDY: The authors report their experience with the use of a biphasic macroporous calcium phosphate bone substitute. MATERIALS AND METHODS: In 23 cases (22 patients) a biphasic macroporous calcium phosphate ceramic was used to fill a pathological bone defect. The ceramic used in this study was a macroporous (400 to 600 mu) component consisting of 60 per cent hydroxyapatite and 40 per cent beta-tricalcium phosphate. It was in the form of granules (2 to 3 mm), sticks (20 x 5 x 5 or 10 x 5 x 5 mm) or custom made blocks. In 6 cases, the ceramic was used alone; in 12 cases with autologous bone marrow and in 5 cases with autologous cancellous bone grafts. In 14 cases, the bone defect was due to conservative treatment of a benign tumor, in 3 cases due to aseptic post-traumatic non union, in 3 cases due to wide resection for malignant tumors of the pelvis and in 3 cases following osteotomy. Post operative assessment was made from clinical, radiographic and histological findings. RESULTS: 2 patients died 6 and 8 months post operatively and 2 were lost to follow up at 2 and 5 months with both having good clinical and radiographic results when last seen. For the remaining 19 cases, the average follow-up was 20 months (from 6 to 62 months). No local, regional or general deleterious effects were noted. Radiologically the bone ceramic junction healed in all cases except 2 within 3 months. In these last two cases, healing required 6 and 7 months. No radiolucent line appeared around the ceramic. No stress fractures occurred in the substitute. Histologically, 3 biopsies showed new bone formation throughout the ceramic with apposition of a well differentiated lamellar bone directly apposed to the ceramic. DISCUSSION: Animal experimentations have proven the interest of similar ceramics: macroporosity enhances bone rehabilitation and the biphasic characteristics associate the advantages of slow resorption of hydroxyapatite and more easily resorbed beta-calcium phosphate. No deleterious clinical, radiographical or histological effects were observed, confirming the biocompatibility of this substitute. Despite the poor mechanical properties of this macroporous ceramic before implantation, good clinical and radiographic results suggest improvement of these properties in the composite new formed bone-ceramic after implantation. CONCLUSION: We believe that macroporous biphasic ceramic is a good substitute for use in bone defects when good primary mechanical stability and contact with the host bone are present. Further clinical and experimental studies are necessary to determine the limits of such a substitute in terms of volume and to control its mechanical properties following implantation.

Adolescent↗
PubMed1995

[Loss of cutaneous substances of the foot. Retrograde flaps, apropos of 4 cases].

We report our experience with two retrograde flaps for the treatment of cutaneous tissue loss of the foot. A lateral supramalleolar flap and a medial plantar flap pediculated distally were used, the first to cover the dorsal aspect and the second to cover the forefoot. Indications for local flaps are limited essentially because of the small size. In addition they cannot always be used for local trauma. Retrograde vascularization for the forefoot is an interesting alternative to more invasive salvage procedures involving distant flaps (cross-leg or flee flaps) requiring and uncomfortable position or microsurgery.

Adult↗
PubMed1994

Sound localization in hemispherectomized patients.

In order to precisely evaluate the consequences of cortical damage on free-field sound localization in humans, the present study examined response accuracy to auditory targets in three hemispherectomized patients and IQ-matched controls. Listeners reported sound location by pointing with their dominant hand to the apparent sound location in an anechoic chamber. Two conditions were tested: (i) localization of a fixed-sound source and (ii) localization of the beginning and the end of a simulated moving stimulus. In both conditions, the responses of the patients were less accurate than those of the controls in the hemifield contralateral to their removed hemisphere. Moreover, the single-case analyses revealed that the performances obtained with fixed sources were generally more precise than those obtained with moving sources. This result is discussed in terms of a differential involvement of cortical and subcortical pathways in the processing of stationary and moving sounds. Finally, the age at surgery and the post-surgical interval were related with the magnitude of the deficits, suggesting the possible influences of functional reorganization and cerebral plasticity.

Adolescent↗
PubMed1994

[Cover of trochanter pressure sores by V-Y musculocutaneous flap of the fascia lata].

Authors report their experience with the V-Y advancement flap in the coverage of trochanteric pressure sores. Nine flaps have been performed concerning 7 patients. Trochanteric sores in paraplegia or tetraplegia may lead to suppurative arthritis of the hip, with a risk of anaerobic infection and acute septicaemia. The treatment has to be as complete as possible. The trochanteric sore is debrided, with special attention given to removing all necrotic material, the surrounding bursa, and the bony prominence of the greater trochanter. The debrided trochanteric region is then covered by a well-vascularized and thick tissue. We observed only one complication at the donor site which can be closed primarily by this technique. The V-Y advancement technique is a new, simple and safe design of tensor fasciae latae flap. The defect is covered by the thicker and the best vascularized portion of the musculo-cutaneous flap. It allows preservation of other donor sites of the gluteal region to cover other sores, which are often associated.

Adult↗
PubMed1993

Sound localization in acallosal human listeners.

In order to evaluate the callosal and hemispheric involvement in sound localization, the present study examined response accuracy to auditory targets in acallosal subjects. The primary interest was to determine whether the congenital absence of the corpus callosum affects auditory localization, especially for sounds situated near the midline of auditory space or moving across it. A corollary objective was to examine the possible existence of an hemispheric asymmetry on audio-spatial localization tasks. Four subjects with callosal agenesis paired to four age and IQ-matched controls and 16 normal control subjects were asked to locate broad band noise bursts at fixed intensity (52 dB sound pressure level) in the horizontal plane in an anechoic chamber. Broad band noise bursts were delivered randomly through 16 loudspeakers, which were mounted at approximately 10 degrees intervals on a perimeter frame. Two conditions were tested: (i) localization of a fixed-sound source; (ii) localization of the beginning and the end of a simulated moving stimulus. Two response modes were used. Listeners reported the apparent stimulus location either (i) by pointing with the ipsilateral index finger or (ii) by calling out the estimated angles indicated on the calibrated sound perimeter. Aiming accuracy was assessed by calculating the mean deviation of the response from the objective target position. The results indicated that the responses of the acallosal subjects were less accurate than those of the controls. The deficit was observed not only at the midline but throughout the auditory field. This points to possible compensatory mechanisms following the early absence of the corpus callosum which are, however, limited. The results obtained with manual pointing were generally more precise than those obtained through oral responses. This difference suggests that the remapping of spatial positions onto a verbally based coordinate system involves a supplementary cognitive step which affects the precision of the response. Comparing the performance to stimulus presentation in the left and right fields indicated that no hemispheric asymmetry was apparent under any of the conditions for either the acallosal subjects or the IQ-matched and normal control subjects.

Adolescent↗
PubMed1993

[Value of cutaneous expansion in the repair of skin defects after posterior surgical intervention on the spine].

Tissue expansion spreads widely its field of application through the treatment of large cutaneous defects. Spinal surgery represents a new field for this technique. Iterative and large posterior midline approach can lead to skin necrosis and deep infection which imposes a second look attempt with ablation of orthopaedic devices. Tissue expansion associated with advancement flaps represents a less aggressive choice to treat such post-surgical complications saving regional skin and muscles rather than with conventional flaps. The authors report four cases in which such a technique was applied with long term satisfactory results.

Adult↗
PubMed1991

[Parosteal sarcoma of the radius in the course of etretinate therapy].

A parosteal osteosarcoma of the right radius has developed in a patient treated for a long time by etretinate (total dose: 73 g). If brachial ossifications have been reported to etretinate in 2 cases, they were benign tumours; so coincidence is possible in our case. Nevertheless, a relation between the tumour and the treatment cannot be excluded and justify the report of this observation.

Bone Neoplasms↗
PubMed1989

Effect of exogenous insulin on plasma free carnitine levels during exercise in normal man.

Preliminary data from our laboratory have shown that the decrease in plasma free carnitine levels normally found during prolonged exercise is blunted in type 1 diabetic man. This study was designed to test the hypothesis that this might be due to the sustained peripheral hyperinsulinemia seen during exercise in diabetics treated by subcutaneous insulin. Ten male subjects underwent 90 min of cycle ergometry at 60% of their maximal oxygen uptake capacity on two occasions, one with and the other without a constant 0.13 mU.kg-1.min-1 i.v. insulin infusion. Blood samples were taken at rest, during exercise, and after exercise for measurement of plasma glucose, insulin, C-peptide, free fatty acids, and carnitine. Plasma glucose dropped significantly (p less than 0.01) from basal during both infusions, but values at 30, 45, and 60 min of exercise were lower (p less than 0.05) during insulin infusion compared with the saline infusion. Exercise produced a significant (p less than 0.01) fall in plasma insulin in both infusions. However, from 30 to 90 min of exercise, the plateau insulin level was higher during the insulin infusion compared with the saline infusion (91.4 +/- 3.0 vs. 32.9 +/- 3.0 pmol/L; p less than 0.001). Plasma C-peptide decreased significantly (p less than 0.01) during exercise and recovery in both infusions, but values between infusions were not significantly different. Plasma free fatty acids increased significantly (p less than 0.01) at 90 min of exercise during the saline infusion, while during the insulin infusion this was noted during recovery only.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗