[Intravitreal viscoelastic injection for management of combined choroidal and retinal detachments]. / Injection intra-vitréenne de produit viscoélastique pour la gestion des décollements choroïdiens associés aux décollements de rétines.

INTRODUCTION: Combined retinal detachment and choroidal detachment (RDCD) is a serious type of retinal detachment occurring mainly in high myopes, which poses many pre-, intra- and postoperative difficulties that can affect the visual prognosis. MATERIAL AND METHODS: Personal technique used in 8 patients with RDCD, consisting of intravitreal injection (IVI) of a viscoelastic (VE) device 2 to 3 days prior to vitrectomy. RESULTS: Reattachment of the choroid in all patients, with return to normal IOP, allowing vitrectomy to be performed under optimal conditions. DISCUSSION: RDCD often occurs in high myopia, especially in the case of an associated giant tear, the mechanism of which involves severe hypotony, resulting in a vicious cycle including development of the choroidal detachment (CD), partial retinal reattachment, normalization of the IOP, redetachment of the retina, and once again, hypotony. Preoperative viscoelastic IVI can break this vicious cycle and reattach the choroid, often within 24 to 48hours. This thus facilitates RD surgery without the intra- and postoperative technical difficulty of managing the CD. CONCLUSION: Viscoelastic IVI is a simple, safe, inexpensive and reproducible technique for the treatment of CD associated with RD in order to prepare for RD surgery under the usual conditions without a CD.

Influence of bio-lubricants on the orthodontic friction.

The Friction force of Stainless Steel (SS) and Nickel-Titanium (Ni-Ti) rectangular archwires against stainless steel brackets was investigated. Two types of brackets were used namely: Self-ligating brackets (SLB) and conventional brackets (CB). The friction tests were conducted on an adequate developed device under dry and lubricated conditions. Human saliva, olive oil, Aloe Vera oil, sesame oil and sunflower oil were used as bio-lubricants. The friction force was examined as a function of the ligation method and oil temperature. It is found that under oil lubrication, the friction behavior in the archwire/bracket assembly were the best. The SLB ligation was better than the conventional ligation system. The enhancement of the frictional behavior with natural oils was linked to their main components: fatty acids.

[Extensive iatrogenic coronary dissection during coronary angioplasty: a series of 19 consecutive patients]. / Dissection coronaire extensive compliquant une angioplastie: à propos d'une série de 19 cas consécutifs.

PURPOSE OF THE STUDY: Extensive coronary dissection is a rare complication of intraluminal angioplasty. We report a retrospective study of 19 patients who consulted in a general hospital without cardiac surgery. PATIENTS AND METHODS: After consulting our coronarography and angioplasty database, we included the extensive coronary dissections (type D, E and F) in our study. The medical files of the selected patients were analysed. RESULTS: Between January 2003 and March 2010, 19 coronary angioplasty (total: 2542) were complicated with extensive dissections (incidence 0,75%). For 62,3% of the patients, the dissection was related to the guiding catheter. Eleven patients had type A and B1 lesions. The dissections affected the right coronary artery for 16 patients, the left anterior descending coronary artery for two patients and the left main coronary artery for one patient. After angioplasty, a final TIMI flow 3 was obtained for only 11 patients. In nine cases, we observed a limited extension to the aorta that did not need a chirurgical intervention and had no influence on the prognosis. The complications were common, such as death (n=1), coronary bypass (n=2), myocardial infarction (n=8), cardiogenic shock (n=2) and circulatory assistance (n=2). CONCLUSION: Extensive coronary dissection is a rare complication of angioplasty. The right coronary is the most frequent vessel concerned and an extension to aorta is usual. The treatment is usually based on sealing the entry with a coronary stent. The complications are common and serious and we did not find any predicting factors to extensive coronary dissections that are unpredictable.

Aortic length changes during abdominal aortic aneurysm formation, expansion and stabilisation in a rat model.

BACKGROUND: Determinants of extracellular matrix (ECM) destruction/reconstruction balance influencing abdominal aortic aneurysm (AAA) diameter may impact length. OBJECTIVE: Document aortic lengthening, its correlation to diameter, and determine how treatments that impact diameter also affect length. METHODS: Three hundred and fifty-five diameter and length measurements were performed in 308 rats during AAA formation, expansion and stabilisation in guinea pig aortas xenografted in rats. Impact of modulation of ECM destructive/reconstructive balance by endovascular Vascular Smooth Muscle Cell (VSMCs) seeding, TIMP-1, PAI-1 and TGF-beta1 overexpression on length has been assessed. RESULTS: Length increased in correlation with diameter during formation (correlation coefficient (cc): 0.584, P<0.0001) and expansion (cc: 0.352, P=0.0055) of AAAs. Overexpression of TIMP-1 and PAI-1 decreased lengthening (P=0.02 and 0.014, respectively) demonstrating that elongation is driven by matrix metalloproteinases and their activation by the plasmin pathway. Overexpression of TGF-beta1 controlled length in formed AAAs (17.3 ± 9.6 vs. 5.9 ± 7.4mm, P=0.022), but not VSMC seeding, although both therapies efficiently prevented further diameter increase. Length and diameter correlation was lost after biotherapies. CONCLUSION: Length increases in correlation with diameter during AAA formation and expansion, as a consequence of ECM injury driven by MMPs activated by the plasmin pathway. Correlation between length and diameter increases is not universally preserved.

New insight in aetiopathogenesis of aortic diseases.

BACKGROUND: Knowledge in the aetiopathogeny of aortic disease helps to characterise aortic lesions better and determine the risk of evolution and therapeutic strategies as well. This article focusses on aneurysms and dissections, and excludes causes related to infection, systemic inflammatory diseases and trauma. METHODS AND RESULTS: The biomedical literature of the past 10 years has been reviewed here. Aortic diseases are heterogeneous along the aorta as far as their genetic determinants, contribution of smooth muscle cells, inflammation and thrombus formation are concerned. Degradation of extracellular matrix by proteases causing aortic disease is a 'terminal' event, modulated by genetic background, haemodynamic strain, cellular events and thrombus formation. New genetic determinants of aortic disease have been identified. Proteases degrading the aortic wall are derived from a variety of cell types in addition to macrophages, including neutrophils on the luminal thrombus, mesenchymal and endothelial cells in the wall. Smooth muscle cells contribute to aortic wall homeostasis against inflammation and proteolysis. The degradation of the wall is followed by, or paralleled with, a failure of aortic reconstruction. CONCLUSIONS: Aortic diseases are diverse, and involve a multiplicity of biological systems in the vascular wall and at the interface with blood. Future research needs to unravel distinct cellular and molecular mechanisms causing the clinical events, in particular, dissection, expansion of already formed aneurysms and rupture.

[Plasmocytoma of the skull base revealing multiple myeloma]. / Plasmocytome de la base du crâne révélant un myélome multiple.

We report a case of sphenoidal plasmocytoma in a 57-year-old male revealing multiple myeloma. MRI showed a tumor located in the sphenoid sinus with local extension. Diagnosis was made by histology after transsphenoidal resection. We discuss the imaging features of plasmocytomas and review the principal differential diagnoses.

Theoretical and numerical study of a bone remodeling model: the effect of osteocyte cells distribution.

It is well argued that osteocytes are mechanosensory cells and are involved in the regulation of bone remodeling. In previous works, the predictions from a simulation model have suggested that both the influencing distance of osteocytes and the magnitude of the mechanical loads determine the thickness of trabeculae whereas the number of osteocytes primarily affects the rate of bone remodeling. The question that remains not completely answered is: for the same number of osteocytes, what is the effect of different distributions on the remodeling process? Based on a particular regulatory bone remodeling model, the question is addressed, in part, by performing a stability analysis in connection with numerical simulations. The results allow us to demonstrate that, on one hand, we cannot reach a conclusion about the stability of the model for a nonuniform osteocyte distribution. This implies that there is no relationship between the different parameters conveying the stability of the model. On the other hand, we show that the osteocyte cell distribution has a significant influence on the bone morphology, which seems to be confirmed by simulations with real data obtained from rat tibia.

Mechanical analysis of a prototype of small diameter vascular prosthesis: numerical simulations.

This paper concerns a mechanical analysis of a prototype of a small diameter vascular prosthesis made of a fibre reinforcement silicone material. The theoretical approach is carried out for a neoHookean strain energy function augmented with unidirectional reinforcing that is characterized by a single additional constitutive parameter for strength of reinforcement. Numerical simulations based on a finite element model compare the compliance of different grafts and predict the degree of the compliance mismatch in an anastomosis between native artery and vascular prosthesis. Furthermore, specific applied strains on the prototype, viewed as arising surgical manipulation and implying telescopic shear have been simulated. Thus, for different fibre reinforcements, the stress gradient through the wall of the tubular structure is evaluated.

Damaged-bone adaptation under steady homogeneous stress.

In this work an extension of the adaptive-elasticity theory is proposed in order to include the contribution of bone microdamage as a stimulus. Some aspects of damaged-bone tissue adaptation, brought about by a change of the daily loading history, are investigated. In particular, under the assumption of a small strain approximation and isothermal conditions, the solution of the remodeling rate equation for steady homogeneous stress is discussed and the damage effect upon the remodeling time constant is shown. The result is both theoretical and numerical, based on a recent theory of internal damaged-bone remodeling (Ramtani, S., and Zidi, M., 1999, "Damaged-Bone Remodeling Theory: Thermodynamical Approach, " Mechanics Research Communications, Vol. 26, pp. 701-708. Ramtani, S., and Zidi, M., 2001, "A Theoretical Model of the Effect of Continum Damage on a Bone Adaption Model," Journal of Biomechanics, Vol. 34, pp. 471-479) and motivated by the works of Cowin, S. C., and Hegedus, D. M., 1976, "Bone Remodeling I: Theory and Adaptive Elasticity," Journal of Elasticity, Vol. 6, pp. 471-479 and Hegedus, D. H., and Cowin, S. C., 1976, "Bone Remodeling II: Small Strain Adaptive Elasticity," Journal of Elasticity, Vol. 6, pp. 337-352.

[Corneal acid burning after facial peeling]. / Brûlure cornéenne acide après peeling du visage.

We describe the case of a 66-year-old woman who had previously undergone facial peeling and developed severe bilateral corneal burn due to direct contact Exopeel((R)) with her eyes. Despite medical treatment and an amniotic membrane graft, deep stromal opacity persisted in one eye.

[Lipoprotein (a) and ischemic heart diseases in patients with type 2 diabetes]. / Lipoprotéine (a) et cardiopathies ischémiques chez les patients diabétiques de type 2.

Lipoprotein (a) is a new independent coronary risk factor, but the role of lipoprotein (a) in type 2 diabetes remains controversial. The objective of this study was to demonstrate the relationship between the level of lipoprotein (a) and the coronary artery diseases (CAD) in type 2 diabetes. Recruitment was carried out in 3 groups of patients: Group 1: 110 control subjects, Group 2: 115 diabetics (D), Group 3: 105 diabetics with CAD (DC). The mean age was, 51 + 7; 52 + 6; 56 + 6 respectively. Total cholesterol, triglyceride, HDL-C, LDL-C, Apo A-I, Apo B and lipoprotein (a) were measured for the patients. The Lp (a) level was significantly higher in the diabetic groups as compared to the controls (p < 0.05), but this level was different between D and DC: 312 + 232 vs 347.8 + (NS). However, when the Lp (a) level is higher than 300 mg/ml, there is a significant difference between DC and D (53% vs 42% p = 0.05). There is no correlation between Lp level and total cholesterol; however, there is a significant variation of Lp (a) level with LDL-C (r = -0.14, P = 0.01). There is a negative correlation between Lp (a) and HDL-C (r = -0.13, p = 0.03), Lp (a) and ApoA-I (r = - 0.11, p = 0.05); but there is a positive correlation between Lp (a) and ApoB (r = 0.14, p = 0.02). Lp(a) level higher than 300 mg/L constitutes a coronary risk factor in type 2 diabetes. This contributes, with the other lipid disorders, to the increase of the coronary risk factors in diabetes.

[Prognosis of infectious endocarditis]. / Pronostic de l'endocardite infectieuse.

OBJECTIVE: To study clinical course and prognostic factors of infective endocarditis. PATIENT AND METHODS: Infective endocarditis was identified in 126 consecutive patients (criteria of DURACK). Of these, 73 were male, mean age was 29.9 + 15 years, 98 (77.7%) had past history of cardiac disease. The evolution has been marked by 38 deaths (30%) in spite of the recourse to surgery (69 patients). The mean follow-up period was 52 months, the event-free survival was 61% at 5 years. RESULTS: By univariate analysis the predictors of bad prognosis: Large vegetations > 10 mm, delay of apyrexia > 10 days presence of a neurological accident and the absence of surgical treatment. Multivariate analysis: Vegetation > 10 mm (OR 1.97, 1-4.1, p = 0.05), presence of a neurological accident (OR:2.76, 1.32-5.76, p = 0.007) and the absence of surgical treatment (OR: 5.03, 2-11.4, p < 0.001). CONCLUSION: Infective endocarditis remains a serious affection, identification of patients with poor prognosis should lead to early surgical referral: this attitude provides good immediate and long-term results.

Compressibility of the carotid artery in patients with pseudoxanthoma elasticum.

The arterial wall has generally been considered as noncompressible in in vitro studies. However, compressibility of the arterial wall (CAW) has never been studied in vivo in humans. Large interstitial proteoglycans play a major role in sustaining the compression generated by pulsatile forces. The aims of the present study were to develop an experimental methodology for the assessment of CAW in vivo in humans and to study CAW in patients with pseudoxanthoma elasticum (PXE), a genetic disease characterized by proteoglycan accumulation and fragmented, swollen, and calcified elastic fibers in connective tissues. We studied 19 female patients with PXE and 15 normal female control subjects matched for age and blood pressure. A high-resolution echo-tracking system was used for the continuous determination of internal diameter and wall thickness at the site of the common carotid artery. Matrices of the radiofrequency signal were analyzed with a dedicated software to measure carotid wall cross-sectional area every 4 milliseconds during 4 to 6 cardiac cycles. CAW was calculated as the stroke change in cross-sectional area. CAW was 44% higher in patients with PXE than in control subjects (6.8+/-2.6% versus 4.7+/-2.7%, respectively; P<0.05). In control subjects, CAW decreased with age in a linear manner (r=-0.75, P<0.01). In PXE patients, the relationship with age was not homogeneous: CAW tended to increase with age before 40 years (P=0.07) and significantly decreased with age in older patients (P<0.01). Carotid geometry and elastic properties did not differ between PXE patients and control subjects. In conclusion, CAW was measurable in vivo and noninvasively in humans. The higher CAW of PXE patients compared with that of control subjects suggests that proteoglycans are important determinants of compressibility.

A theoretical model of the effect of continuum damage on a bone adaptation model.

Throughout life, bone is continuously turning over by the well-regulated processes of bone formation and resorption. Everyday activities damage bone, and this damage is normally repaired in a continuous remodelling process. When an imbalance in this remodelling process occurs, bones may become more susceptible to fracture. This paper is devoted to a theoretical modelling of the competition between damage and internal remodelling in bones. The general theory of adaptive damaged-elastic materials proposed here as a model for the physiological process of damaged-bone remodelling follows the general framework of continuum thermodynamics where new damaged-bone remodelling law and associated thermodynamical restrictions are stated, and specialized to the case of small strain in isothermal processes. An attempt is also made to derive: (a) the damage force (adaptive damage energy release rate ) which controls the microcracks propagation and arrest, and (b) the damage rule by introducing damage thresholds and loading/unloading conditions.

Stability analysis and finite element simulation of bone remodeling model.

Bone remodeling is widely viewed as a dynamic process--maintaining bone structure through a balance between the opposed activities of osteoblast and osteoclast cells--in which the stability problem is often pointed out. By an analytical approach, we present a bone remodeling model applied to n unit-elements in order to analyze the stationary states and the condition of their stability. In addition, this theory has been simulated in a computer model using the Finite Element Method (FEM) to show a relationship between the bone remodeling process and the stability analysis.

Bone remodeling theory applied to the study of n unit-elements model.

The aim of this paper is to illustrate the application of mathematical tools for the analysis of non-linear dynamical systems to the study of global stability of one kind of bone remodeling scheme applied to n unit-elements model. The particular aspects analyzed here are the stationary states related to this theory and a condition of their stability. The non-linear equations governing the remodeling process are solved by finite-difference method and the well-known results on the heterogeneous spatial organizations have been retrieved and confirm the analytical study. This kind of remodeling theory is useful for investigating the effects of physiological parameters on the development, maintenance, and adaptation of bone under mechanical loading.