Understanding the preferences of water users in a context of cyanobacterial blooms in Quebec

Algal blooms, whether they are harmful or more akin to a nuisance, do pose negative impacts on human well-being. In the province of Quebec, excessive phosphorus that contributes to the problem of cyanobacterial blooms comes mainly from non-point sources. Limited regulation on the management of this nutrient leads to its strong accumulation in soils and, combined to climate change effects, contributes to increasing the magnitude of the effects of algal blooms on humans and the environment. The presence of cyanobacteria in water has impacts on its colour, texture and odour, in addition to posing threats to the health of recreationists, as some cyanobacteria are known to release toxins during blooms. This research focuses on studying the impacts of algal bloom events on recreationists and people living close to affected waterbodies. More specifically, we explore the preferences of individuals for different ecosystem services (ES), mainly cultural ES, provided by waterbodies (i.e., recreational activities, aesthetic aspects, and ecological health). We also estimate the average willingness to pay, financed through an increase in municipal taxation, for mechanisms that would allow the resolution of this issue. To achieve these objectives, we use a choice experiment approach, enclosed in a questionnaire that was carried out in person to 252 people. Conditional logit with and without interactions, and a random parameter logit (mixed logit) are alternatively used. Results show that individuals value first their ability to perform recreational activities, followed by the ecological health of waterbodies, and the aesthetic aspects (i.e., odour and visual aspects). Interestingly, the fact that people reported taking part in fishing activities influenced the way they prioritized ES in the choice modelling exercises. Based on the most robust model, we estimate the average willingness to pay at CA$353/household per year to fund a suite of solutions aimed at improving overall water quality.

Method for Finding Mass-Absorption Coefficients by Empirical Equations and Graphs

A brief description of the theoretical approach of this new method is given. The main purpose of the method is to correlate in a more logical order not only the data yielding the two laws relating mass-absorption coefficient to wavelength and to atomic number, respectively, but also to delineate, within two discontinuities, the relationship existing between each value and the other ones taken as a whole. The empirical equation relating μ to λ is μ = Cλn. A table of complete values for the constant C and die power n to be assigned in the equation is given for finding the values of mass-absorption coefficients above unity for all elements (except hydrogen) and for all wavelengths between 0.17837 and 10 A. It is believed that until a complete set of experimental data obtained with modern equipment is available, this proposed method fills the enormous gaps between actual compiled values.

Abstract P5-09-07: Risk reducing strategy in germline BRCA mutated patients with locally advanced breast cancer. Establishing mastectomy as a preventing procedure of local recurrence

Introduction

Neoadjuvant chemotherapy (NAC) is proposed for locally advanced breast cancer (LABC) to increase the breast conservative treatment (BCT). In France, mastectomy is the risk-reducing prophylactic surgical strategy only for pre-symptomatic germline BRCA-mutated (gBRCAm) patients. On the other hand, BCT is proposed to all patients following NAC based on clinical response, regardless the gBRCAm status. The aim of this retrospective study is to evaluate the risk of local recurrence (LR) according to BRCA status.

Patients and methods

Inclusion criteria were: (i) patients treated for unilateral LABC, T2-3, N≥0, M0 by NAC, and (ii) patients who underwent germline BRCA screening. , using targeted next-generation screening, was carried out either during NAC (rapid process) or after surgery. Deleterious mutations were confirmed using Sanger sequencing before passing on the results to the clinical geneticist. Some gBRCAm patients from Olympia study were also included. Patients were followed-up over a long term for overall survival, LR and disease-free survival. Chi-square and Fischer test were used to generate statistical comparison.

Results

Between 2007 and 2015, 988 women were treated for LABC at our institution. Among them, 151 patients underwent clinical genetic testing for gBRCAm based on these criteria: young age at diagnosis or familial history of breast or ovarian cancer or histological characteristics as grade 2/3, Her2-3+ or basal like. A total of 122 patients were included in the study; 28 patients had gBRCAm status and no mutations were detected in 94 patients (wtBRCA). Significant differences between the two groups (gBRCAm vs wtBRCA) were observed for

Mean age, (36.7 vs 40.1y (p=0.0032) ,

Intrinsic tumor subtypes basal like (64.3% vs 42.5%, p=0.0432)

ER are more often negative (21.4% vs 46.8%, p=0.0165).

Among the 30 patients who underwent BRCA screening during NAC and eligible for BCT, 8 of the 9 patients with gBRCAm choose mastectomy (88%). Among the 92 patients with screening mutation after breast cancer treatment, 5 of the 19 patients with gBRCAm had a mastectomy (28%). In the 28 gBRCAm patients, 15 had a BCT and 13 a mastectomy. In the 94 wtBRCA patients, 67 had a BCT and 27 a mastectomy. After a follow-up of 4.32 years, we observed 8 relapses, 5 LRs after BCT and 3 contro-lateral relapses. Of the 5 LRs, 3 came from 15 gBRCAm with BCT and 2 of the 67 wtBRCA (p=0.0403).

Discussion

In this selected subgroup of patients, gBRCAm rate is higher (23%) than the rate based on familial criteria for BRCA testing (12%). Regarding the rationale for BCT or mastectomy procedure in LABC and pre-symptomatic gBRCAm patients, this study led us to establish mastectomy as risk-reducing strategy in a sole surgery procedure for gBRCAm patients. Moreover, 88% gBRCAm patients chose mastectomy; the mastectomy rate was lower when the patient was unaware of their BRCA status (26%). The LR rate was higher in the gBRCAm vs wtBRCA with a statistical difference. In LABC patients with high genetic risk, the knowledge of mutation status could influence patients' and surgeons' choice of surgery. In case of gBRCAm status, mastectomy is recommended to decrease LR risk.

Citation Format: Tunon de Lara C, Leroux J, Bonnet F, Debled M, Barrouk-Simonet E, Quenel-Tueux N, Lagarde P, Chassaigne F, Esnaud T, Fournier M, Bubien V, Breton-Callu C, Charitansky H, Petit A, Mathoulin-Pelissier S, Macgrogan G, Longy M, Sevenet N. Risk reducing strategy in germline BRCA mutated patients with locally advanced breast cancer. Establishing mastectomy as a preventing procedure of local recurrence [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-09-07.

Legg-Calvé-Perthes disease

Current knowledge of the causes and risk factors of Legg-Calvé-Perthesdisease (LCPD) does not allow effective preventive strategies. The outcome in adulthood is usually good. Hip osteoarthritis rarely develops before 50 years of age. The risk of osteoarthrosis depends chiefly on the final degree of joint incongruence. Age at onset and the lateral pillar classification are the two main outcome predictors and serve to guide the surgical indications based on the studies by Herring's group. Non-operative treatment is not effective. In contrast, femoral varus osteotomy and Salter's innominate osteotomy provide good outcomes. In severe forms, however, combining these two techniques or performing a triple pelvic osteotomy seem preferable. Surgery is now performed considerably less often than in the past, as it is effective only in patients with lateral pillar group B or B/C disease with onset after eight years of age. In other situations, therapeutic abstention is recommended.

[Slipped capital femoral epiphysis]

Slipped capital femoral epiphysis (SFCE) is a disorder of the hip, characterized by a displacement of the capital femoral epiphysis from the metaphysic through the femoral growth plate. The epiphysis slips posteriorly and inferiorly. SCFE occurs during puberty and metabolic and epidemiologic risk factors, such as obesity are frequently found. Most chronic slips are diagnosed late. Sagittal hip X-rays show epiphysis slip. In case of untreated SCFE, a slip progression arises with an acute slip risk. Treatment is indicated to prevent slip worsening. The clinical and radiological classification is useful to guide treatment and it is predictive of the prognosis. In situ fixation of stable and moderately displaced SCFE with cannulated screws gives excellent results. Major complications are chondrolysis and osteonecrosis and the major sequelae are femoroacetabular impingement and early arthritis.

Cervical myelopathy involving os odontoideum and retro-odontoid cyst treated with Harms C1-C2 arthrodesis

An episode of acute decompensation of cervical myelopathy occurred after an injury without fracture of an os odontoideum associated with a compressive retro-odontoid cyst. The 51-year-old female patient presented Fränkel C, Nurick grade 4 neurological status and pyramid syndrome. The initial MRI demonstrated an intramedullary T2 hyperintense signal in the context of spinal cord narrowing. The retro-odontoid cyst demonstrates atlantoaxial instability related to the os odontoideum. Harms C1-C2 arthrodesis without laminectomy was performed and the cyst disappeared completely. Spinal cord decompression was thus obtained on the MRI taken 3 months later. Neurological recovery was complete and continued at 1 year.

[Are C2 pedicles always screwable? Calibration and planning with a pedicle-lamina angle]

INTRODUCTION

Posterior cervical arthrodesis is associated with osteosynthesis. C2 pedicular screwing affords a good bone anchoring but involves neurological and vascular risks.

PURPOSE

To determine C2 pedicular screwing feasibility from a large cohort of cervical CT scans. To describe the visible anatomical parameters during a surgical procedure in order to plan and secure it.

MATERIALS AND METHODS

Retrospective consecutive series of 100 cervical CT scans was analyzed. Cases with upper cervical fracture were excluded. C2 surgical anatomy was assessed according to maximum length, minimum width and minimum height. Angular parameters were pedicle-transverse angle and sagittal angle. Original pedicle-lamina angle was used as a visible mark during the procedure independent of the patient's position. Pedicular screwing feasibility was evaluated. It was arbitrarily defined by a lower minimum height less than 4mm.

RESULTS

Two hundred C2 pedicles were analyzed with 7.5% that were not screwable. Their mean length was 26.2mm, with a mean width of 5.2mm and a mean height of 9.2mm. Mean pedicle-transverse angle was 36.2°, mean sagittal angle was 25.8° and mean pedicle-lamina angle was 81.3°.

CONCLUSION

C2 pedicle screwing feasibility is inconstant due to anatomical variability. In fact, 13% of patients have at least one non-screwable pedicle. Preoperative planning is essential to achieve this procedure. A pedicle-lamina angle can be used which remains independent from the patient's position.

Surgical treatment using The Unit Rod in children with neuromuscular scoliosis

The article represents a retrospective clinical and radiological study. Objective. To assess the safety and the stability in time of the Unit Rod instrumentation in the treatment of severe neuromuscular scoliosis in children and adolescents. Summary. The treatment of patients with neuromuscular scoliosis always represents a challenge. The patients are debilitated and usual interventions are very long with great loss of blood. Serious complications can compromise the result of the surgery. The technique we used (the Unit Rod) is worldwide recognized, is simple, and gives excellent stability with a low rate of complications. Methods. We conducted a clinical and radiological retrospective study with a follow-up of at least 4 years in 58 patients with serious neuromuscular conditions, most of them being non-walkers. They were surgically treated by using mostly the Unit Rod technique, in the department of Paediatric Orthopaedics of the Rouen University Hospital, France, between 2000 and 2008. The back fusion was generally from T2 to pelvis. We used the Galveston technique for the patients who needed a pelvic fixation. Results. The mean Cobb angle correction was of 67% immediately after surgery; the correction of the curve decreased in time only in 4% of the cases. Pelvic obliquity was also very well corrected: 73% immediately and 70% at the last radiological follow-up. The mean operative time was of 175 minutes compared to 269 minutes for screws and hooks instrumentation. The most common complication for our technique was the radiolucent halo that appeared around the pelvic inserts. There was no significant degradation in time of the correction obtained. Conclusions. The use of this technique is safe, gives excellent results, achieving significant improvements in the postoperative functional status of the patients. The intra- and postoperative complications were minor. The advantage of using this method is the low cost of the material and technical simplicity, the corrective results being the same as the ones obtained with other techniques.

Evolution of adolescent idiopathic scoliosis: results of a multicenter study at 20 years' follow-up

INTRODUCTION

To date there is no consensus on therapeutic indications in adolescent idiopathic scoliosis (AIS) with curvature between 30° and 60° at the end of growth.

OBJECTIVE

The objective of this study was to assess outcome in patients with moderate AIS.

MATERIAL AND METHODS

A multicenter retrospective study was conducted. Inclusion criteria were: Cobb angle, 30-60° at end of growth; and follow-up > 20 years. The data collected were angular values in adolescence and at last follow-up, and quality of life scores at follow-up.

RESULTS

A total of 258 patients were enrolled: 100 operated on in adolescence, 116 never operated on, and 42 operated on in adulthood. Mean follow-up was 27.8 years. Cobb angle progression significantly differed between the 3 groups: 3.2° versus 8.8° versus 23.6°, respectively; P < 0.001. In lumbar scoliosis, the risk of progression to ≥ 20° was significantly higher for initial Cobb angle > 35° (OR=4.278, P=0.002). There were no significant differences in quality of life scores.

DISCUSSION

Patients operated on in adolescence showed little radiological progression, demonstrating the efficacy of surgical treatment for curvature greater than 50°. Curvature greater than 40° was progressive and may require surgery in adulthood. Lumbar scoliosis showed greater potential progression than thoracic scoliosis in adulthood, requiring fusion as of 35° angulation.

LEVEL OF EVIDENCE

IV, retrospective study.

[Fishtail deformity after a non-displaced supracondylar humeral fracture in childhood: A case report]

We report the case of a 13-year-old boy presenting with stiffness and pain in the elbow, which had appeared a few years before consultation. He reported a history of a closed, nondisplaced supracondylar fracture of the humerus 7 years before. Progression was good after orthopedic treatment. X-rays and CT showed a distinctive deformation, called a fishtail deformity, associated with severe arthritic injuries. We recall here that supracondylar fractures of the humerus are common in children and that early reduction decreases the complication rate. However, this case shows that fishtail deformity is a late and serious complication, which may occur after a nondisplaced supracondylar fracture of the humerus, with no severity factors and with good early progression.

Surgery for slipped capital femoral epiphysis in adolescents

The treatment of slipped capital femoral epiphysis (SCFE) in adolescents remains controversial. The goal of initial treatment is to prevent further slippage of the epiphysis. In mild forms, both stable and unstable, in situ fixation is widely accepted as the reference treatment. In contrast, several techniques are available for stable moderate-to-severe SCFE. In unstable moderate-to-severe SCFE, emergent reduction with decompression and internal fixation is currently the preferred method. Selection of the surgical technique rests on an appraisal of advantages versus drawbacks. The goal of this review is to discuss the various surgical methods available for SCFE in adolescents.

Sacro-iliac joint arthroscopy for arthrodesis after traumatic dislocation. Cadaver and clinical feasibility study

BACKGROUND

Sacro-iliac arthrodesis usually requires an extended posterior approach, which is associated with a number of dreaded complications. Here, we assessed the feasibility of arthroscopic exploration of the dislocated sacro-iliac joint.

MATERIALS AND METHODS

In the first step of our study, we used ligament section to induce loss of sacro-iliac joint coaptation in a cadaver. We then studied 5 patients with Tile C pelvic ring injuries. Arthroscopy was used to clear the joint of fibrous tissue and to roughen the bone to subchondral level in order to induce sacro-iliac arthrodesis. In addition, posterior fixation was performed using a hinge system or an ilio-sacral screw.

RESULTS

The cadaver study confirmed the feasibility of sacro-iliac arthroscopy after disruption of the strong posterior inter-osseous ligament. In the clinical part of the study in 5 patients with Tile C pelvic ring injuries, arthroscopy allowed direct visualisation extending to the anterior part of the joint space. A power burr and synovial knife were introduced to remove the interposed fibrous tissue and to roughen the bone to subchondral level in order to induce joint fusion. In addition, percutaneous or open posterior fixation was performed in all 5 patients. No infectious complications were recorded.

DISCUSSION

An arthroscope cannot be introduced into the normal sacro-iliac joint. In contrast, after traumatic sacro-iliac dislocation, arthroscopy can be used to evaluate the intra-articular injuries and to roughen the bone to subchondral level.

Early diagnosis of thoracolumbar spine fractures in children. A prospective study

INTRODUCTION

Early detection of spine fractures in children is difficult because the clinical examination does not always raise worrisome symptoms and the vertebrae are still cartilaginous, and consequently incompletely visualized on routine X-rays. Therefore, diagnosis is often delayed or missed.

HYPOTHESIS

The search for a "breath arrest" sensation at the moment of the trauma improves early detection of thoracolumbar spine fractures in children.

MATERIALS AND METHODS

This was a prospective monocentric study including all children consulting at the paediatric emergency unit of a single university hospital with a thoracolumbar spine trauma between January 2008 and March 2009. All children had the same care. Pain was quantified when they arrived using the visual analog scale. Clinical examination searched for a "breath arrest" sensation at the moment of the trauma and noted the circumstances of the accident. X-rays and MRI were done in all cases.

RESULTS

Fifty children were included with a mean age of 11.4 years. Trauma occurred during games or sports in 94% of the cases. They fell on the back in 72% cases. Twenty-three children (46%) had fractures on the MRI, with a mean number of four fractured vertebrae (range, 1-10). Twenty-one of them (91%) had a "breath arrest" sensation. Fractures were not visualized on X-rays in five cases (22%). Twenty-seven children had no fracture; 19 of them (70%) did not feel a "breath arrest". Fractures were suspected on X-rays in 15 cases (56%).

DISCUSSION

The search for a "breath arrest" sensation at the moment of injury improves early detection of thoracolumbar spine fractures in children (Se=87%, Sp=67%, PPV=69%, NPV=86%). When no fracture is apparent on X-rays and no "breath arrest" sensation is expressed by the child, the clinician can be sure there is no fracture (Se=26%, Sp=100%, PPV=100%, NPV=53%).

LEVEL OF EVIDENCE

Level III.

[Open elbow dislocation with distal ischemia: a therapeutic emergency]

We report the case of a 13-year-old boy with a traumatic elbow dislocation, open stage 2 (Cauchoix and Duparc), with distal ischemia. Exposure of the neurovascular humeral bundle through the wound accentutated the clinical emergency. This clinical observation consisted of elbow dislocation with all severity criteria: (i) opening of the skin, (ii) association with a fracture of the medial humeral epicondyle, and (iii) neurological deficit in the territory of the median nerve. The purpose of this report is to remind physicians that no investigation should delay surgery in elbow dislocation. Despite initial distal ischemia, no vascular exploration is required. Early reduction of the disloction is the key point of care.

Les fractures de Mac Farland

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.

Traitement de l’instabilité postérieure de l’épaule par butée iliaque ou acromiale

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.

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.

[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.

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.

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.

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.

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.

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.

[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.

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.