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Biomedical subjects

J Leroux

Publications and source records attributed to J Leroux.

At least 19 recordsLinked to original sources
PubMed2005

[Mac Farland fractures: a retrospective study of 26 cases].

PURPOSE OF THE STUDY: MacFarland fractures are known to have poor prognosis. There is a major risk of misalignment due to the formation of an epiphysiodesis bridge. The purpose of this study was to evaluate the functional and radiological outcome of these fractures in a retrospective series of patients. MATERIAL AND METHODS: We analyzed retrospectively the cases of 26 patients (14 boys and 12 girls), mean age 11 years 6 months (range 7-15) with MacFarland fractures. The Salter and Harris classification was Salter III (n = 17) and Salter IV (n = 9). Surgery was used for 21 patients and cast immobilization for five. Mean follow-up was 28.4 months (19-63 months). None of the children were lost to follow-up. Outcome was noted good (no stiffness, no pain, no limp, no misalignment, no surgical complication, no healing problem), fair (stiffness and/or pain and/or limp and/or healing problem without misalignment, no surgical complication), or poor (misalignment or surgical complication). RESULTS: The three-months postoperative assessment showed three patients with ankle pain, five with stiff ankles, one with a medial problem (snapping) and two with wound healing complications. The long-term outcome was considered good for 24 patients and fair in two (one wound adherence and one hypertrophic scar tissue). There were no poor outcomes. DISCUSSION: We used surgery more than is generally reported by other teams, opting for surgery when the displacement was 1 mm rather than the 2 mm used by others. Surgical treatment was arthrotomy in all cases to achieve anatomic reduction under direct view, followed by osteosynthesis. For some, this therapeutic scheme may be considered too surgical. In order to achieve anatomic reduction, we use an epiphyseal lag screw for cancellous bone to achieve better compression of the fracture line. A washer is also used to improve compression and maintain perfect reduction. Theoretically, the washer could raise the risk of perichondral virola and consequently an iatrogenic epiphysiodesis bridge, but we have not had any problems in our experience. Arthrotomy did not lead to ankle stiffness, which is feared by some, in any of our patients.

Adolescent↗
PubMed2004

Frontostriatal deficits in fragile X syndrome: relation to FMR1 gene expression.

Fragile X syndrome (fraX) is the most common known cause of inherited developmental disability. fraX is associated with a CGG expansion in the FMR1 gene on the long arm of the X chromosome. Behavioral deficits, including problems with impulse control and distractibility, are common in fraX. We used functional brain imaging with a Go/NoGo task to examine the neural substrates of response inhibition in females with fraX (ages 10-22) and age- and gender-matched typically developing subjects. Although subjects with fraX had significantly lower IQ scores, as a group their performance on the Go/NoGo task was equivalent to that of the typically developing group. However, females with fraX showed abnormal activation patterns in several cortical and subcortical regions, with significantly reduced activation in the supplementary motor area, anterior cingulate and midcingulate cortex, basal ganglia, and hippocampus. An important finding of our study is that neural responses in the right ventrolateral prefrontal cortex (PFC) and the left and right striatum were correlated with the level of FMR1 gene expression. Our findings support the hypothesis that frontostriatal regions typically associated with response inhibition are dysfunctional in females with fraX. In addition to task-related activation deficits, reduced levels of "deactivation" were observed in the ventromedial PFC, and, furthermore, these reductions were correlated with the level of FMR1 gene expression. The ventromedial PFC is a key node in a "default mode" network that monitors mental and physiological states; we suggest that self-monitoring processes may be aberrant in fraX.

Adolescent↗
PubMed2004

[Surgical treatment of posterior instability of the shoulder joint using an iliac bone block or an acromial pediculated bone block: outcome in eighteen patients].

PURPOSE OF THE STUDY: The posterior bone block procedure is a popular option for the treatment of involuntary posterior instability of the shoulder. The purpose of this study was to analyze the long-term results of this procedure using an iliac bone graft and to point out the advantages of Kouvalchouk technique using an acromial pediculated block. MATERIAL AND METHODS: Eighteen patients, ten men and eight women, mean age 27 years, were reviewed: thirteen were active in sports activities including four at the competition level. The duration of symptoms before surgery was four years on the average. One patient experienced recurrent dislocation, twelve suffered regular involuntary subluxation, and five had painful shoulders possibly related to posterior instability considering the arthroscopic findings. For nine patients (group 1), an iliac block was combined with the soft-tissue procedure. In nine others (group 2), the procedure described by Kouvalchouk was used to create a posterolateral acromial bone block with pediculated deltoid fibers. Functional outcome was assessed with the 100-point Duplay score. The position of the bone block and osteoarthritis were assessed on plain x-rays. RESULTS: Mean follow-up was 13.5 years in group 1 and 3.5 years in group 2. Four patients needed a revision procedure to remove a screw. At last follow-up, the average Duplay score was 78 points. Nine patients returned to their former sports activities. Seven patients were pain free and ten had moderate discomfort at effort. We did not observe any recurrent dislocation no subluxation but did have six patients who described apprehension. The mean Duplay score was 70 points in group 1 and 86 points in group 2. In two patients in group 1, the x-rays showed signs of grade 3 or 4 osteoarthritis, which was related to an intra-articular screw in one; the other patient had had the same degenerative signs before surgery. Two patients developed grade 1 osteoarthritis. DISCUSSION AND CONCLUSION: The bone block procedure is effective for posterior instability of the shoulder. Occurrence of osteoarthritis, compared with the anterior bone block, is lower after long-term follow-up. The results of the Kouvalchouk procedure with an acromial pediculated bone block look promising. We recommend an additional capsuloplasty when inferior hyperlaxity is associated with posterior instability.

Acromion↗
PubMed2003

[Follow up of total hip prothesis: storage phosphor versus screen-film radiography].

PURPOSE: Digital radiography may lead to interpretation difficulties in patients with hip prosthesis, especially when initial evaluation was performed using screen film radiography. The purpose of this study was to evaluate inter-observer and inter-technique reproducibility comparing digital and screen-film radiography. MATERIAL AND METHODS: Twenty-eight patients with unilateral (n=24) or bilateral (n=4) hip prosthesis (total=32 prostheses) underwent screen-film and digital (storage phosphor) radiography. The bone-cement and metal-cement interfaces were evaluated for the presence of a lucent line in 14 different sectors reclassified into 3 regions. This evaluation was performed by two independent readers. Inter-observer and inter-technique reproducibility were calculated using kappa values. RESULTS: The inter-observer reproducibility was negligible, poor or average with Kappa values ranging from 0.07 to 0.47. The degree of agreement between the two methods was poor, average or good for both observers with Kappa values ranging from 0.10 to 0.66. CONCLUSION: Although inter-technique agreement is not high, it is better than inter-observer agreement. Therefore, storage phosphor technique should not be rejected for total hip prosthesis follow-up, even though previous films were screen-film radiographs.

Adult↗
PubMed2002

Instability driven fragmentation of nanoscale fractal islands.

Formation and evolution of fragmentation instabilities in fractal islands, obtained by deposition of silver clusters on graphite, are studied. The fragmentation dynamics and subsequent relaxation to the equilibrium shapes are controlled by the deposition conditions and cluster composition. Sharing common features with other materials' breakup phenomena, the fragmentation instability is governed by the length-to-width ratio of the fractal arms.

Journal Article↗
PubMed2001

N-isopropylacrylamide copolymers for the preparation of pH-sensitive liposomes and polymeric micelles.

Hydrophobically-modified copolymers of N-isopropylacrylamide bearing a pH-sensitive moiety were investigated for the preparation of pH-responsive liposomes and polymeric micelles. The copolymers having the hydrophobic anchor randomly distributed within the polymeric chain were found to more efficiently destabilize egg phosphatidylcholine (EPC)/cholesterol liposomes than the alkyl terminated polymers. Release of both a highly-water soluble fluorescent contents marker, pyranine, and an amphipathic cytotoxic anti-cancer drug, doxorubicin, from copolymer-modified liposomes was shown to be dependent on pH, the concentration of copolymer, the presence of other polymers such as polyethylene glycol, and the method of preparation. Both polymers were able to partially stabilize EPC liposomes in human serum. These polymers were found to self-assemble to form micelles. The critical association concentration was low (9--34 mg/l) and influenced by the position of the alkyl chains. In phosphate buffered saline, the micelles had a bimodal size distribution with the predominant population having a mean diameter of 35 nm. The polymeric micelles were studied as a delivery system for the photosensitizer aluminum chloride phthalocyanine, (AlClPc), currently evaluated in photodynamic therapy. pH-Responsive polymeric micelles loaded with AlClPc were found to exhibit increased cytotoxicity against EMT-6 mouse mammary cells in vitro than the control Cremophor EL formulation.

Acrylamides↗
PubMed2000

Characterization of thermosensitive chitosan gels for the sustained delivery of drugs.

The aim of this study was to investigate the physical properties of a chitosan/glycerophosphate (GP) thermosensitive solution which gels at 37 degrees C and evaluate the in vitro release profiles of different model compounds. The gelation rate was dependent on the temperature and on the chitosan deacetylation degree. The solution containing 84%-deacetylated chitosan could be stored 3 months at 4 degrees C without apparent change in viscosity. The in vitro release profiles of the model compounds depended on the presence of GP in the chitosan solution, on their molecular weight and on the presence of lysozyme in the release media. They were not affected by the electrostatic charge of the model compound when present at low concentrations. During the first 4 h, the release was accompanied by a substantial loss of the gel weight which was mainly attributed to the leaching of water and excess GP. Scanning electron micrographs revealed that the solutions yield gels with a highly porous structure after 24 h of exposure to a continuous flow of phosphate buffered saline. These results indicate that the chitosan/GP thermosensitive solutions gel rapidly at body temperature, can remain in the sol state at 4 degrees C and can sustain the delivery of macromolecules.

Chitin↗
PubMed1999

Polymeric micelles - a new generation of colloidal drug carriers.

Polymeric micelles have recently emerged as a novel promising colloidal carrier for the targeting of poorly water soluble and amphiphilic drugs. Polymeric micelles are considerably more stable than surfactant micelles and can solubilize substantial amounts of hydrophobic compounds in their inner core. Due to their hydrophilic shell and small size they sometimes exhibit prolonged circulation times in vivo and can accumulate in tumoral tissues. This review examines the chemical nature of polymeric micelles as well as the methods used to characterize them with regard to drug delivery. Special emphasis is put on the determination of critical micelle concentration and on drug loading procedures. Potential medical applications, especially in cancer chemotherapy, are described and discussed.

Animals↗
PubMed1998

Polymeric nano- and microparticles for the oral delivery of peptides and peptidomimetics.

Due to recent advances, numerous bioactive peptides are now available in large quantities. Administering these substances by the oral route appears as a formidable challenge due to their insufficient stability in the gastrointestinal tract and their poor absorption pattern. Several approaches have been investigated to improve their oral bioavailability. Among them, the use of polymeric particulate delivery systems (microparticles and nanoparticles) represents a promising concept. Encapsulating or incorporating peptides in particles should at least protect these substances against degradation and, in some cases, also enhance their absorption. The aim of this paper is to review the principal studies where peptide-loaded particles were administered by the oral route. The preparation methods and in vitro trials are presented and in vivo results are discussed with emphasis placed on the peptide blood levels reached or on the biological effects observed. Whether or not intact particles can be taken up and translocated to the systemic circulation is not the aim of this review.

Journal Article↗
PubMed1998

Isoleucylation properties of native human mitochondrial tRNAIle and tRNAIle transcripts. Implications for cardiomyopathy-related point mutations (4269, 4317) in the tRNAIle gene.

A growing number of mutated mitochondrial tRNA genes have been found associated with severe human diseases. To investigate the potential interference of such mutations with the primordial function of tRNAs, i.e. their aminoacylation by cognate aminoacyl-tRNA synthetases, a human mitochondrial in vitro aminoacylation system specific for isoleucine has been established. Both native tRNAIleand isoleucyl-tRNA synthetase activity have been recovered from human placental mitochondria and the kinetic parameters of tRNA aminoacylation determined. The effect of pathological point mutations present in the mitochondrial gene encoding tRNAIlehas been tackled by investigating the isoleucylation properties of wild-type and mutated in vitro transcripts. Data show that: (i) modified nucleotides contribute to efficient isoleucylation; (ii) point mutation A4269G in the gene (A-->G at nt 7 in the tRNA), associated with a cardiomyopathy, does not affect aminoacylation significantly; (iii) point mutation A4317G (A-->G at nt 59 in the tRNA), reported in a case of fatal infantile cardiomyopathy, induces a small but significant decrease in isoleucylation. The potential implications of these findings on the understanding of the molecular mechanisms involved in the expression of pathology are discussed.

Adenine↗
PubMed1998

[The role of the national education physician in the management of child abuse].

The school physician is in a key position to detect and to report cases of child ill-treatment. He has opportunities to listen to the child himself, to collect information upon his life at school as well as on his brothers and sisters; therefore he can get an accurate knowledge of the situation of that child. Afterwards, he will meet the child's parents. Through his relationships with many partners, such as the family physician, the hospital, educators, social workers and even justice, the school physician can clear up some facts, in order to complete his view on the case. Due to his particular responsibility to cope with situations of child distress, the school physician, as an adviser inside school, shall take an active part in terms of prevention.

Child↗
PubMed1996

[Isolated blow out fracture of the medial wall of the orbit with medial rectus entrapment. Apropos of 3 cases].

We report three cases of isolated medial orbital wall blow out fracture with medial rectus entrapment. Few cases have been reported in the literature, predominantly in black people as in this paper. Predominance of this rare fracture in black population could be explained by an anatomic hypothesis based on racial origin. The diagnosis is often suggested by the medial rectus entrapment. Depending on the position of the incarceration in front of or behind the equator of the eyeball, the eye presents pseudo-Duane syndrome or exotropia with decreased adduction. The diagnosis is established by orbital computed tomography visualizing the lamina papyracea of the ethmoid bone fracture and the medial rectus incarceration. This exceptional fracture must be detected to avoid complications: enophthalmos and motility disturbances.

Adolescent↗
PubMed1991

[Halfway houses].

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Acquired Immunodeficiency Syndrome↗