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Biomedical subjects

R Ledoux

Publications and source records attributed to R Ledoux.

At least 19 recordsLinked to original sources
PubMed1994

The exoscope--a frame-based video/graphics system for intraoperative guidance of surgical resection.

A system has been devised to focus a video camera mounted on a CRW stereotactic frame onto the surgical field and to integrate the video picture with a computer-generated three-dimensional view of structures or targets deep within the brain. The surgical resection can then be done with the surgeon looking either at the composite picture on the video/computer monitor (as in almost all endoscopic surgery) or at the surgical field, to perform the resection using the conventional techniques most comfortable to the surgeon and most effective for the resection. The graphics platform on which the Exoscope program is built is the same as used for the RSA X-Knife stereotactic radiosurgery system. The X-Knife graphics program allows the reconstruction of a target mass (such as intracranial tumor) and desired objects (such as surrounding vessels) with accurate registration to stereotactic coordinates derived from the CRW localizing system. By mounting a video system through an externally mounted endoscope on the CRW arc, it is possible to orient the video image with great accuracy to this same stereotactic space. The two images are superimposed on a computer/video console in the operating room. The surgeon visualizes a real-time video image of the operating field upon which is a graphical representation of the computer-generated image of the target mass beneath the surface. In the corners are triplane orthogonal views through the center of target and a view parallel to the trajectory, so the surgeon may gauge his or her progress toward the target.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Graphics↗
PubMed1989

Nondestructive investigations on ninety-seven surgically excised mammary prostheses.

The information contained in the medical files of 68 patients having undergone surgical excision of a total of 97 internal mammary prostheses allowed us to define a typical patient profile at time of first implantation. Age: 33 years 11 months, height: 1.59 m, weight: 51.5 kg, two children. Twenty-one percent of these patients had the operation done subsequent to a mastectomy, while 79% requested it for cosmetic reasons. The duration of implantation was less than 55 months for 76% of the prostheses received after excision. The most frequent evolutive complications were the formation of a fibrous capsule followed by silicone bleeding, as well as mineralization. Macroscopic examination of the 97 explanted prostheses provided information on their integrity (38.1% of prostheses ruptured), gel differentiation (24.7%), sticky surfaces (26.8%), surface deposits (33%), memory folds (54.6%), and Dacron fixation patches (20.6%). According to the medical files, a fibrous capsule was found in association with 69.8% of the breast implants. We received only 46 capsules. The average thickness was 1.4 mm. Mineralizations were present on 15 capsules (32.6%). Two zinc phosphates were identified, for the first time, in human body: parascholzite and hopeïte. Statistical examination showed that Heyer-Schulte prostheses stayed in place for a longer time. Integrity and gel differentiation depended on the duration of the implantation. Presence of mineralization was model-related (Dow Corning prostheses were associated with deposits) and depended on the presence of fixation patches.

Adult↗
PubMed1989

First observation of hopeïte and parascholzite in fibrous capsules surrounding silicone breast implants.

We observed mineralization in 32.6% of the capsular tissue of 97 mammary prostheses recovered after surgical excision. Three distinct mineralogical phases were identified. The first was composed of common hydrated carbonate hydroxylapatite, a well-known physiological and pathological mineral. Hopeïte and parascholzite constituted the second and third phases. They are zinc and calcium hydrate phosphates that have not been observed previously in human tissues. Statistical analysis of the data showed relationships between the presence of mineralizations and the manufacturers on the one hand, and the presence of Dacron fixation patches at the surface of the prostheses on the other.

Breast↗
PubMed1986

Assessment of IgE-mediated sensitivity during immunotherapy: comparison of the RAST with and without adsorption of IgG to titrated prick skin tests.

The effect of specific IgG induced by allergy immunotherapy on specific IgE binding in the RAST was assessed by removal of the IgG with staphylococcus protein A bound to Sepharose. In sera from those patients with the highest titers of specific IgG, RAST binding was increased 8% following adsorption of the post-immunotherapy sera while in sera obtained from the same patients before immunotherapy adsorption increased binding only 3%. The effect of allergy immunotherapy on the titrated prick skin test was compared to the effect on the RAST to the same allergen. In nine patients who received the highest dose of grass extract, the area of the titrated prick skin tests was reduced following immunotherapy by 75%. Staphylococcus protein-A adsorption of sera from these patients drawn before immunotherapy resulted in an increase in RAST binding of 2.7% compared to an increase of 6% in sera obtained after immunotherapy, suggesting suppression of RAST binding of only 3% by specific IgG. It is concluded that RAST levels are affected less than prick skin tests by the immunologic response to allergy immunotherapy. Some interference in RAST binding is produced by specific IgG antibody in high titers, but for many critical purposes the degree of interference is not significant.

Absorption↗
PubMed1985

An investigation of possible immunologic reactions to human serum albumin used as a stabilizer in allergy extracts.

Two hundred fifteen patients who had received allergy immunotherapy for at least 1 year with an extract preparation containing 0.03% human serum albumin (HSA) were tested for evidence of an immunologic reaction to HSA by immediate skin testing. Sera from 39 of these subjects and from control subjects were studied in a microtiter enzyme-linked immunosorbent assay for anti-HSA antibodies. The 39 subjects' sera were examined by immunoelectrophoretic analysis for evidence of "tailing albumin" indicative of HSA bound to immunoglobulins. All studies were negative. We conclude that in these patients HSA-containing allergy extracts used in immunotherapy failed to induce the production of specific antibodies against HSA. This suggests that HSA was a safe extract stabilizing agent for allergy extracts in these representative allergic patients.

Allergens↗