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Biomedical subjects

G Pasquier

Publications and source records attributed to G Pasquier.

At least 19 recordsLinked to original sources
PubMed1998

Experimental evaluation of a percutaneous injectable biomaterial used in radio-interventional bone-filling procedures.

Interventional radiology is beginning to be used in bone pathology. An injectable biomaterial Ethibloc*, composed of alcohol and a vegetal protein (zein), has been successfully used for percutaneous treatment of benign bone lesions. The reasons for this success remained unknown and needed to be understood. In this study, using a rabbit model, an evaluation was made of bone formation and tissue reaction during the first weeks after the injection of this biomaterial. Ethibloc* was injected percutaneously into bone defects in rabbit distal femurs. Three time intervals were studied: 2, 4 and 8 wks. The three control groups constituted unfilled, polymethylmethacrylate (PMMA), and alcohol. Undecalcified bone technique was used for a qualitative analysis and histomorphometric evaluation. A low bone formation was found which was less than in the control groups (PMMA and unfilled). The "Ethibloc group" was characterized by an early inflammatory reaction. Good clinical results obtained with Ethibloc* probably arose, after an initial vascular thrombosis, from a secondary bone reaction and spontaneous osteogenesis obtained after the disappearance of vascular or hyperpression reaction.

Journal Article↗
PubMed1998

[Development of a model which makes it possible to test injectable bone substitutes and evaluation of a calcium phosphate cement].

New percutaneous filling techniques are beginning to be used in bone tumor pathology. The purpose of this study was to develop a reproducible model for testing new injectable bone substitutes. A closed cancellous bone defect was created in the distal femoral condyles of rabbit. Bone defect was filled by a percutaneous injection. Several situations were tested: spontaneous evolution of unfilled cavities, evolution of cavities filled either with a conventional orthopedic cement (PMMA), either with a mixed collagen-hydroxyapatite material, either with a biomaterial derived from the vegetal protein zein, either with a calcium phosphate cement brushite type. The new bone formation was quantified in the defect for each group in which several delays were tested. A bone defect of reproducible size was obtained consistently. A partial bone formation was observed in the unfilled group. The best bone formation rate was obtained in the phosphate cement group. This model showed the interest of injectable biomaterials and more precisely the interest of the phosphate calcium cements as brushite.

Animals↗
PubMed1996

Resorption of, and bone formation from, new beta-tricalcium phosphate-monocalcium phosphate cements: an in vivo study.

Hard cylinders (4.7 x 10 mm) of two kinds of beta-tricalcium phosphate-monocalcium phosphate monohydrate-calcium sulfate hemihydrate (beta-TCP-MCPM-CSH) cements with and without beta-TCP granules (500-1000 microns) were implanted into holes drilled in rabbit femoral condyles for up to 16 weeks. Empty cavities were used as control. Cement resorption and new bone formation in the cylinders were evaluated with contact microradiography and quantified through an automatic image analysis system. At 4 weeks, both kinds of cement cylinders were surrounded by new bone. At 8 weeks, except for beta-TCP granules, both cement cylinders were almost completely resorbed and replaced by bone tissue. At 16 weeks the bone in the cavities of both cements recovered a trabecular pattern, but only the bone trabeculae in the initial cavity of the cement with beta-TCP granules became thick and mature. However, the cavities of the empty control were still empty and large. These results show that the beta-TCP-MCPM-CSH cements stimulate bone formation and are rapidly replaced by bone tissue. When added with nonresorbable beta-TCP granules, this cement maintains bone formation for a longer time.

Animals↗
PubMed1995

Outcome of Chiari pelvic osteotomy in adults. 90 hips with 2-15 years' follow-up.

We studied retrospectively 90 Chiari osteotomies in 83 adults with pain, hip dysplasia and arthrosis. At follow-up after 6 (2-15) years, 35 hips were pain-free, 38 had rare or slight pain, and 17 had moderate or severe pain. The dysplastic acetabulum was corrected in all but 5 cases. There was diminution of arthrosis in 36 hips, no change in 38, and worsening in 16 hips. Functional outcome was best when surgery was performed before the age of 40, and in hips with the greatest degree of dysplasia. However, two thirds of the patients aged over 40 years at surgery had a good result.

Adolescent↗
PubMed1994

[Reconstruction of the acetabulum using femoral head autograft in total hip arthroplasties].

We have reviewed, at a mean follow-up of 63.7 months, 36 total hip replacements performed with bulk acetabular autograft. Before surgery all the hips had acetabular insufficiency. Improvement of acetabular coverage was achieved in all cases with the patient's femoral head screwed to the ilium. Only one massive graft resorption was observed, simultaneous to loosening of the socket. Partial graft resorption was observed in 6 cases, and was not correlated with loosening of the socket. In all cases we observed radiographic features consistent with graft incorporation. Periprosthetic ossifications were noted in 13 cases. At follow-up, four sockets were loose, among which were included three Weill threaded rings. The mean functional improvement scores evaluated with the Merle d'Aubigné hip rating were: 4 points for pain, 2.7 points for mobility, and 2.4 points for walking. The authors concluded that femoral head, used as a massive autograft during total hip replacement, was a safe procedure for bone stock reconstruction in case of severe acetabular insufficiency.

Acetabulum↗
PubMed1994

Causes of dislocation of total hip arthroplasty. CT study of component alignment.

We reviewed radiographs and CT scans of 38 total hip arthroplasties which had dislocated (36 posteriorly; 2 anteriorly) and compared the alignment of the prosthetic components with those of 14 uncomplicated arthroplasties. No difference was found between the alignment of the prosthetic components in the two groups. In the seven patients who had reoperations, the cause of dislocation diagnosed by CT was confirmed in only two cases (one retroversion of the cup and one protruding osteophyte). Muscular imbalance rather than malposition of the components was the major factor determining dislocation. CT allows accurate measurement of cup and neck anteversion but contributes little to preoperative planning.

Adolescent↗
PubMed1982

[Aneurysms in Takayasu disease].

Takayashu's inflammatory panarteritis essentially results in stenotic lesions of the supra aortic axes and the collateral vessels of the abdominal aorta. Fusiform, segmental post-stenotic dilatation is commonly observed. Three particular types of aneurysms are described, each illustrated by a case report: --aneurysm of the ascending aorta causing severe aortic regurgitation by dilatation of the aortic ring: the diagnosis of Takayashu's disease was made in a young West Indian female on the evidence of associated aortic lesions and calcification of the descending thoracic aorta. The patient underwent replacement of the ascending aorta and aortic valve replacement. This form is very rare, although mild aortic regurgitation in Takayashu's disease has been reported in about ten cases by different workers; --large saccular aortic aneurysm. This lesion of the descending thoracic aorta with parietal calcification and without intrasaccular thrombosis was associated with a long, irregular stenosis of the paroxismal segment of the aorta, giving rise to signs of coarctation, and with multiple stenoses of the supra-aortic axes in a 31 year old Algerian. Surgical cure was realised by occluding the orifice in order to avoid replacing the aorta at the origin of the main medullary arteries. An ascending aorta-abdominal aorta bypass was performed at the same time, together with correction of the stenoses of the supra-aortic vessels. A few similar cases of large succular aneurysms of the thoracic or abdominal aorta or of the large collateral vessels have previously been described; --pseudo-aneurysm due to arterial rupture and formation of a large hematoma. A 20 year old Algerian presented with a polylobulated saccular aneurysm of the superficial femoral artery in the femoral triangle. Several stenotic lesions typical of Takayashu's disease (including a particularly rare stenosis of the contra lateral superficial femoral artery) were associated. At surgery, the lesion was found to be a pseudo-aneurysm with no true arterial wall on histological examination. The role of an infective endarteritis is discussed and excluded. This type of lesion does not appear to have been previously reported. These three varieties of aneurysm were the presenting signs of Takayashu's disease in the cases reported.

Adult↗
PubMed1981

[Clinical application of the alkalosis induction test for coronary artery spasm].

Alkalosis was used for stress testing for coronary artery spasm in 70 patients (average age: 56 years) with resting angina. A rapid intravenous infusion of an alkaline buffer (THAM) immediately followed by 5 minutes' maximal ventilation increased the arterial pH to 7.67 +/- 0.5. Anginal pain and ECG changes were observed in 24 Patients, with ST elevation in 10 cases and ST depression in 14 cases. The ischaemic changes occurred during hyperventilation in 16 cases and in the 3 minutes following the test in 8 cases. The heart rate increased from 66 +/- II to 71 +/- 14 bpm (p less than 0,01) but systolic blood pressure fell from 139 +/- 12 to 130 +/- 12 mm Hg during hyperventilation; there was no significant change in the rate-pressure product (1130 +/- 1750 to 8990 +/- 2690). In all cases, the angina and ischaemic changes regressed after intravenous Trinitrin. Coronary angiography was performed in 56 patients: in the 24 patients with positive responses (Group I) and in 30 of the 46 patients with negative responses (Group II). Significant coronary artery narrowing (greater than 70%) was observed in 21 patients of Group I: in the 3 patients without coronary lesions an intravenous injection of 0.4 mg methylergometrine provoked coronary spasm. In Group II, significant narrowing was demonstrated in 18 patients: in the 12 other patients, coronary spasm could not be induced by methylergometrine. Therefore, in the absence of organic coronary lesions, an excellent correlation has been shown between the alkalosis and methylergometrine tests. This stress test was repeated in 16 of the 24 patients in Group I one hour after administration of 20 mg of Nifedepine: the test was negative in all cases. We conclude that the alkalosis test could be useful in the coronary care unit as a stress test for coronary spasm to determine the antianginal treatment of choice and to evaluate its efficacity.

Coronary Angiography↗
PubMed1977

[Long-term results of aortocoronary bypass. 1. Clinical aspects].

Eighty patients undergoing one or several aorto-coronary bypass graft procedures had longterm clinical and arteriographic follow-up (mean follow-up period of two years, extremes 1 and 6 years). The indication fort operation in these patients was unstable angina in 39 (49%), threatened infarction in 16 (20%), Prinzmetal's angina in 8 (10%), and stable but incapacitating angina in 17 (21%). Significant lesions involved the three coronary trunks in 49 cases, two trunks in 25 cases, and one trunk in 6 cases. The longterm clinical results were excellent in 65% of cases, and fair in 26%; the procedure failed in 9% of cases. Angina pectoris either disappeared or improved in 96% of cases. After operation, myocardial infarctions occurred in 11 cases (14%), 7 of which were early and 4 late with a delay of 1 to 4 years. The pre-operative cardiac failure disappeared or decreased in 13 cases out of 16. Finally the quality of the clinical results does not seem to be influenced by the various indications for operation with the exception of Prinzmetal's angina, where the results have been excellent in all cases (8 cases out of 8).

Adult↗
PubMed1977

[Long-term results of aortocoronary bypass. 2 Angiographic aspects].

Follow-up arteriograms carried out between one and six years (mean follow-up period two years) in 80 cases of aorto-coronary bypass graft procedures showed a good correlation between the quality of the clinical results obtained -- as detailed in the first part of this article -- and a larger proportion of patent grafts: 82% of 130 grafts had remained patent, and 94% of patients have all or some of their grafts patent. Late occlusion of the grafts is rare, and does not appear to be influenced by abnormalities of the graft found at early follow-up, these abnormalities being fairly stable. These follow-up have especially shown the good correlation between the quality of the clinical results and the functional status of the coronary network in the long term, a function not only of the permeability of the grafts which have been carried out, but also of the complete or incomplete correction of the lesions of the three coronary trunks. Such a complete procedure which was carried out or could have been carried out in only 30% of the total patients, was then successful in 94% undergoing it. The clinical results should therefore lead us to carry out operations which remove the lesions as completely as possible.

Adult↗