Biomedical subjects

V Langlois

Publications and source records attributed to V Langlois.

7 recordsLinked to original sources

PubMed2006

[Evaluation of an articulated spacer for two-stage reimplantation for infected total knee arthroplasty: 28 cases].

PURPOSE OF THE STUDY: Two-stage reimplantation remains the most popular solution for infected total knee arthroplasty. We have used articulated spacers since their introduction in 2000. We evaluated tolerance, joint motion under general anesthesia before reimplantation and also the infectious and functional long-term outcome. MATERIAL AND METHODS: Between June 2000 and April 2003, we implanted an articulated spacer in 28 patients who required revision of their total knee arthroplasty. Postoperatively, contact weight bearing was allowed with unlimited knee motion depending on pain control. Mean time between implant removal and reimplantation was eight weeks (range 6-16 weeks). RESULTS: There was one dislocation due to excessive play between the two components. Passive joint motion before reimplantation was 53 degrees (range 5-80 degrees ). At last follow-up, 24 patients were free of overt infection and all antibiotic regimens had been discontinued for at least 20 months (20-48 months). Two patients required a second two stage revision. One had an arthrodesis and in one only suppressive antibiotic therapy was possible. DISCUSSION: Spacer removal appears easy at reimplantation. Good knee flexion (greater than 40 degrees in ten patients and greater than 60 degrees in eight) facilitated exposure, avoiding the need for tilting of the tibial tuberosity in seven patients. Functional and infectious outcomes were similar to those reported in the literature. CONCLUSION: The spacer appears to improve patient comfort between the two operations. It also facilitates the reimplantation procedure because of the easier exposure and greater knee flexion compared with a mono-bloc spacer or an external fixator. There must however be enough bone stock to hold the articulated spacer in place.

Arthroplasty, Replacement, Knee↗

PubMed2005

[Physeal distraction for limb length discrepancy and angular deformity].

PURPOSE OF THE STUDY: Physeal distraction or chondrodiastasis uses the growth plate as a zone of least resistance. Application of force thus provokes distraction and opening of the plate (Salter and Harris type I epiphyseal detachment). Progressive lengthening allows room for regenerate bone and enables limb lengthening and correction of angular deformations. MATERIAL AND METHODS: Twenty chondrodiastasis procedures were performed in fifteen patients. Mean age was 14.4 years (10.3-15.7). The underlying causes were trauma (n = 6), constitutional deformation (n = 8), infection (n = 2, distal lateral femoral epiphysiodesis), and malformation (n = 4). The localizations were: proximal tibia (n = 11), distal tibia (n = 4), distal femur (n = 4), distal radius (n = 1). The surgical procedure involved installation of an external fixator on either side of the physis after planification of the desired correction and taking into account the remaining growth potential of the physis. The distraction was performed by the patient at the rate of 1 mm per day. A one-sided external fixator was used for eleven patients (distal femoral correction and proximal tibial hemichondrodiastasis for angular deformation) and a circular fixator (to control 3D correction) in nine. Complications were noted according to the four grades of severity described by Caton. RESULTS: Mean follow-up was 26.1 months. Epiphyseal detachment was achieved in all patients, even in the presence of an epiphysiodesis bridge, in 7.7 days on average (2-15 days). Mean lengthening was 4.75 cm, mean angular correction was 22.2 degrees (mean preoperative angle 20.5 degrees ). For chondrodiastasis (symmetrical physeal distraction), the mean duration of correction was 4.6 months (1-9), mean time to healing was 8.3 months (4-13) and mean healing index was 55.6 days/cm (Verone). For hemichondrodiastasis (asymmetrical physeal distraction), mean duration of correction was 1.3 months (1-3), and mean time to healing was 2.7 months (2-5). The healing index was different and was 3 days per degree. Complications were studied using the Caton classification. There were 17 (85%) benign complications (not requiring revision under anesthesia) and 6 (30%) serious complications (requiring anesthesia and unplanned revision). There were 2 (10%) severe complications (knee flexion, ankle equinus). DISCUSSION: Chondrodiastasis has specific complications, mainly involving the distal femur (stiff knee, risk of septic arthritis). It provides rapid in situ correction resulting from epiphysiodesis bridges. The resection step proposed by Bollini is not necessary, but the growth plate is definitively sterilized. This implies that the procedure be used for preventive lengthening, depending on the predicted limb length discrepancy. This notion limits indications to older children. Besides the fact that several deformations can be corrected simultaneously, this technique does not require osteotomy and respects vascular supply to the regenerative tissue. It involves the physis responsible for the angular deformation or limb length discrepancy. It does not require internal fixation nor bone grafting and can be performed with weight bearing. Finally, the procedure can be adjusted as needed during the correction phase, with the patient in the standing position.

Adolescent↗

PubMed2003

Study of erodable paint properties involved in antifouling activity.

To produce ecological marine paints, it is necessary to understand the phenomena involved in antifouling activity. Due to the multivariable components which have to be taken into account and due to their analytical intricacy, only studies based on selected properties are conceivable. In this study, four properties have been chosen, viz. erosion, biocide release, roughness and the physicochemical characteristics of the film surface. A principal-component analysis (PCA) of the experimental data has shown that, among the selected properties, only erosion affected antifouling efficiency. A more detailed investigation of erosion by quantifying global hydration and hydrolysis of immersed paints revealed the difficulty in linking the chemical structure of binders to the final erosion properties. Biocide release from paints, quantified by chromatographic methods coupled with UV detection, was inferior to the doses stated by the paint producers. These observations allowed the conceiving of formulations with reduced amounts of active molecules. The development of erodable, biodegradable binders associated with non toxic compounds is a promising way to obtain efficient antifouling paints compatible with existing, preventive systems.

Chromatography, High Pressure Liquid↗

PubMed2000

Polyuria and proteinuria in cystinosis have no impact on renal transplantation. A report of the North American Pediatric Renal Transplant Cooperative Study.

Because cystinotic patients are polyuric and may have severe proteinuria, each of which is a potential risk factor for graft thrombosis, preemptive transplantation for them is questionable. The objectives of this study were to characterize the changes in urine volume and protein excretion at various stages of cystinosis, determine whether there is serologic evidence of hypercoagulability, and review the clinical experience in renal transplantation in cystinotic children. The records of cystinotic patients followed at the Montreal Children's Hospital between 1992 and 1998 were reviewed. Urinary volume, protein excretion, and coagulation markers were collected to determine the glomerular filtration rate (GFR) >50 ml/min/1.73 m2, <20 ml/min/1.73 m2, before and after starting dialysis. In addition, graft failure and graft thrombosis rates were obtained from the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) database. Urinary volume and protein excretion remained elevated throughout different phases of the disease. Coagulation factors were within normal limits for all patients. In the NAPRTCS database there were four thromboses among the 114 patients transplanted cystinotic patients. All these occurred in cadaveric grafts and only one occurred after preemptive transplantation. Despite polyuria and severe proteinuria, children with cystinosis do not appear to be at an increased risk of graft failure or graft thrombosis.

Child↗

PubMed2000

Bioactive functionalized polymer of malic acid for bone repair and muscle regeneration.

A bioactive poly(beta-hydroxyalkanoate) derived from malic acid was prepared and tested on bone repair and muscle regeneration. This functionalized and hydrolyzable polymer was obtained after several steps, the first one being the anionic copolymerization of three malolactonic acid esters. Chemical modifications were carried out on the terpolymer to turn benzyl-protecting groups into carboxyl groups and allyl groups into sulfonate groups. The resulting polymer bore carboxylate, sulfonate, and sec-butyl pendent groups in 65/25/10 molar proportions and were aimed at interacting with heparan binding growth factors. This polymer did not present any toxic effect in cell viability of HepG2 cells, over a large range of concentrations (0.01-0.25 mgl(-1)). Its ability to improve wound healing was tested in vivo and positive results are reported. Furthermore, the bioactivity of this polymer was evaluated using the regeneration model of Extensor digitorum longus (EDL) rat muscle. The study displayed a significant increase in the muscle regeneration and maturation.

Animals↗

PubMed1998

Synthesis and polymerization of benzyl (3R,4R)-3-methylmalolactonate via enzymatic preparation of the chiral precursor.

beta-methylaspartate ammonia-lyase, EC 4.3.1.2, (beta-methylaspartase) from Clostridium tetanomorphum was used to produce a 40/60 molar ratio of (2S,3R) and (2S,3S)-3-methylaspartic acids, 2a and 2b, respectively, from mesaconic acid 1 as substrate, on a large scale. To prepare (3R,4R)-3-methyl-4-(benzyloxycarbonyl)-2-oxetanone (benzyl 3-methylmalolactonate) 6, 2a and 2b were transformed, in the first step, into 2-bromo-3-methylsuccinic acids 3a and 3b and separated. After three further steps, (2S,3S)-3a yielded the alpha, beta-substituted beta-lactone (3R,4R) 6 with a very high diastereoisomeric excess (> 95% by chiral gas chromatography). The corresponding crystalline polymer, poly[benzyl beta-(2R,3S)-3-methylmalate] 8, prepared by an anionic ring opening polymerization, was highly isotactic as determined by 13C NMR. Catalytic hydrogenolysis of lactone 6 yielded (3R,4R)-3-methyl-4-carboxy-2-oxetanone (3-methylmalolactonic acid) 7, to which reactive, chiral, or bioactive molecules can be attached through ester bonds leading to polymers with possible therapeutic applications. Because of the ability of beta-methylaspartase to catalyse both syn- and anti-elimination of ammonia from (2S,3RS)-3-methylaspartic acid 2ab at different rates, the (2S,3R)-stereoisomer 2a was retained and isolated for further reactions. These results permit the use of the chemoenzymatic route for the preparation of both optically active and racemic polymers of 3-methylmalic acid with well-defined enantiomeric and diastereoisomeric compositions.

Aspartate Ammonia-Lyase↗

PubMed1998

Clinical features of X-linked nephrolithiasis in childhood.

X-linked recessive nephrolithiasis (XRN) is a rare hereditary form of progressive renal failure characterized by (1) proximal tubular dysfunction and low molecular weight proteinuria; (2) hypercalciuria with nephrocalcinosis and nephrolithiasis. Because the clinical features are non-specific and variable, affected families in different parts of the world were initially thought to have several distinct syndromes. However, positional cloning of the relevant gene (CLCN5) demonstrated that these families have, in common, mutations affecting a chloride channel expressed throughout the renal tubule. To expand the description of early clinical and pathological manifestations of XRN, we describe three patients diagnosed in the 1st decade of life. Renal tubular dysfunction may be evident even in the neonatal period, hypophosphatemic rickets may develop in the first years of life, and nephrocalcinosis (but not nephrolithiasis) with glomerulosclerosis are consistent features in childhood. One of our patients is indistinguishable from the others on clinical grounds, yet no mutations of the coding regions of the CLCN5 gene were found, raising the possibility of genetic heterogeneity in the XRN syndrome.

Adolescent↗