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Biomedical subjects

L Lemaitre

Publications and source records attributed to L Lemaitre.

At least 19 recordsLinked to original sources
PubMed1991

Compressive strength of some polyalkenoates with or without dental amalgam alloy incorporation.

The present study compares the compressive strength after one week of some conventional glass-ionomer restorative materials with that of glass ionomers reinforced by the addition of ceramic-coated silver or dental amalgam alloy particles to the aluminosilicate glass powder. Apart from the commercially available Ketac Silver and Miracle Mix, experimental mixtures of Fuji II glass-ionomer powder, the old as well as the new version, with various amounts of either a spherical or lathe-cut amalgam alloy were investigated. For the conventional glass ionomers, the mean compressive strength based on all measurements amounts to 159.9 +/- 4.5 MPa. Both formulations of Fuji II have a comparable strength after one-week maturation. The compressive strength of Ketac Silver does not differ significantly from that of Ketac Fill or from that of the conventional glass ionomers investigated. The effect of admixing amalgam alloy on the compressive strength is found to be determined by the shape and the amount of the alloy particles. Moreover, both parameters are interactive with the formulation of the Fuji glass ionomer used for preparation of the mixture. The results indicate that when dental amalgam alloy is added to the glass ionomer, lathe-cut particles are to be preferred but only in an amount up to 20% by weight.

Analysis of Variance↗
PubMed1991

Polycystic ovarian disease: contribution of vaginal endosonography and reassessment of ultrasonic diagnosis.

OBJECTIVE: We evaluated the superiority of vaginal ultrasonography (US) on the abdominal US for the diagnosis of polycystic ovarian disease (PCOD). DESIGN: The US pattern of ovaries was prospectively investigated by abdominal US and, whenever possible, by vaginal US. SETTING: Primary care, institutional. PATIENTS: One hundred forty-four women in whom PCOD was suspected on endocrine grounds and 62 other patients presenting with primary hyperprolactinemia (n = 23) or hypothalamic anovulation (n = 39). MAIN OUTCOME MEASURE: Vaginal US allowed a better analysis of the ovarian stroma. RESULTS: The external ovarian features of PCOD were observed by both routes in less than one third of the 144 patients with PCOD. The internal ovarian features of PCOD were much more frequently observed by vaginal US than by abdominal US (polycystic pattern: 66.7% versus 38.1%, P less than 0.05; increased ovarian stroma: 57.1% versus 4.8%, P less than 0.001). In the 62 patients without PCOD, US features of PCOD were observed in less than 10% of them, except for the uterine width/ovarian length ratio less than 1 and the polycystic pattern (abdominal US: 17% and 34%; vaginal US: 11% and 50%, respectively). CONCLUSIONS: An increased ovarian stroma seems to be the most sensitive and specific US sign of PCOD, providing that it can be investigated by vaginal US.

Abdomen↗
PubMed1991

[Normal imaging of facial sinuses].

The high spatial resolution of computed tomography allows visualisation of the fine structures of the facial skeleton and gives precise information about the anatomy of the nasal cavity, the paranasal sinuses and their relations with adjacent structures. A detailed knowledge of the normal anatomy, particularly of the nasal cavity and ethmoid, is very useful to provide to the surgeon with a precise pre operative surgical map, before transnasal endoscopic ethmoidectomy or management of paranasal sinuses tumors.

Humans↗
PubMed1990

[Computed tomography of the abdomen in 8 cases of pancreatic trauma].

Computed tomography (CT) is an accurate method for detecting pancreatic trauma. There are two pitfalls to its use: the indication of CT and the risk of misinterpretation. The purpose of this study was to evaluate these 2 difficulties. We report our experience and results obtained in 8 patients with pancreatic trauma (7 closed, 1 open). Peritoneal lavage demonstrated an increased amylase level in the fluid in 2 of our patients. Computed tomography was performed as an emergency diagnostic test for 2 patients and secondarily in 6 patients. In 5 patients, the pancreatic injury was considered to be deep with suspicion of a major pancreatic duct lesion and in 3 patients, the lesion was superficial. Six patients had operative confirmation of the CT results. Pancreatic injuries were classified according to Hervé and Arrighis. Four were grade III, 1 grade II, 1 grade I, while CT showed 5 deep injuries and 1 superficial injury in these patients. Two patients with CT signs of superficial injury were not operated. When there is a clinical suspicion and/or a high amylase level in serum, urine or fluid collected from peritoneal lavage, CT must be carried out as part of in the overall strategy of management of isolated pancreatic trauma. We believe that CT is a valuable tool to evaluate the extent of the injury to the pancreatic parenchyma.

Adolescent↗
PubMed1990

[A superior vena cava syndrome of unusual etiology: compression syndrome of the innominate veins].

A 65-year-old hypertensive and atheromatous presented with "unilateral superior vena cava syndrome". Venography and computed tomography scan with hemodynamic studies demonstrated an intermittent compression of the left innominate vein by the supra-aortic trunks, mainly due to the left subclavian artery, during expiration. The late development of symptoms might be due to arterial atheroma coupled with a narrow superior mediastinum. The case described here is a thoracic equivalent of Cockett's syndrome and so can be called "innominate vein compression syndrome".

Aged↗
PubMed1989

A model for the corrosion behavior of dental amalgams.

At high frequencies, electrochemical impedance behavior for corroding dental amalgams cannot be interpreted in terms of a simple Randles equivalent circuit. This may often be ascribed to the imperfect cell geometry resulting in a nonuniform current distribution. However, the insertion of a constant phase element (CPE) in the non-faradaic branch of the equivalent circuit offers a new scope for interpretation as the circuit provides an m-parameter corresponding to the degree of distortion. The decrease of m as a function of time was explained by a mathematical model reflecting an increasing number of pores. Moreover, that same model allows a better understanding of the passivating effect of NaHCO3 and of the differences between conventional and Cu-rich dental amalgams.

Biocompatible Materials↗
PubMed1989

A mechanistic study of the electrochemical corrosion of the gamma 2 phase in dental amalgams. I. Evaluation of the measurements.

Conventional dental amalgams are prone to corrosion of the gamma 2 phase. In an anodic polarization experiment the presence of gamma 2 causes a current peak in the proximity of -250mV vs. SCE. Electrochemical impedance measurements carried out at this potential indicate the occurrence of an impedance curve in two parts. The high frequency part is a semi-circle with its centre below the real axis. Apart from the faradaic impedance and the double layer capacitance, the high frequency part is dominated by the behaviour of the corrosion products layer on the amalgam surface. The low frequency part has the form of a diffusion-like curve. However, since the phase angle is smaller for the above-mentioned case than for a free diffusion, this phenomenon is ascribed to diffusion in a porous layer at the interface between amalgam solution.

Corrosion↗
PubMed1989

A mechanistic study of the electrochemical corrosion of the gamma 2 phase in dental amalgams. II. Introduction of a model.

Electrochemical impedance measurements on conventional dental amalgams at an anodic polarization potential of -250 mV vs. SCE were performed. An initial evaluation was given in part I of this study; in the second part the results are interpreted in terms of a model. The latter, characterized by an equivalent circuit, is a parallel combination of a flat surface and a pore. The selection of appropriate values for the elements of the equivalent circuit leads to a better insight into the corrosion process. Although no simple relationship exists between the circuit elements and the impedance curves, an explanation was found for some typical features of these curves. As an application, the influence of the anodic polarization potential on the impedance curves was studied. Evaluation by means of the model demonstrated the importance of the characteristics of the corrosion products.

Corrosion↗
PubMed1989

Hepatosplenic candidiasis: an overlooked cause of prolonged fever during recovery from an episode of neutropenia.

Two cases of hepatosplenic candidiasis (HSC) are reported occurring after protracted episodes of neutropenia, induced by chemotherapy for acute leukemia in one case and drug hypersensitivity in the other. The disease presented with persistent or recurrent fever after correction of the neutropenia and with splenomegaly. The alkaline phosphatases were elevated. The diagnosis was strongly suggested by abdominal ultrasonography, CT scan and MRI, which showed multiple hepatosplenic defects. It was confirmed by serologic tests for candidiasis, the presence, in 1 case, of circulating candida antigens, and the rapid response to amphotericin B. The diagnosis of HSC should be considered in patients with persistent fever after an episode of neutropenia. Ideally, histologic confirmation is desirable, but this is often obtainable only by open liver biopsy, an aggressive procedure in such patients. Failing this, our 2 cases stress the diagnostic value of noninvasive imaging techniques, serological testing (in particular the discovery of circulating candida antigens) and the response to amphotericin B.

Acute Disease↗
PubMed1988

US demonstration of pyelitis and ureteritis in children.

The authors report a new ultrasonic sign of urinary tract infection in children: thickening of the renal pelvis and/or ureteral wall. This thickening as encountered in 10 children, (10 months to 12 years) all with urinary tract infection, appears to result from inflammatory changes and to correspond to a sonographic sign of pyelitis and ureteritis. These alterations of the walls are similar to striations and folds described in this pathology on intravenous pyelograms. The thickening was the only sign of abnormality of the urinary tract in two cases; it was observed without reflux in four cases. The demonstration of this pattern should lead to further uroradiological investigations and to appropriate treatment.

Child↗
PubMed1987

Ultrasonographic findings in thymic lymphoma in children.

The sonographic manifestations of thymic involvement by T lymphoblastic non-Hodgkin's lymphoma/leukaemia in 6 children are presented. The criteria which may help in its differentiation from a normal thymus gland are reviewed. Hypoechoic and non-homogeneous large masses are the most typical presentation of thymic infiltration. Fixity of tumour and compression of surrounding structures are the most important associated signs with pleural and pericardial effusions. In children, ultrasonography of the mediastinum can play a role by establishing the nature of anterior masses.

Child, Preschool↗
PubMed1987

The sonographic evaluation of normal thymus in infants and children.

Sonography has been used to evaluate 50 "asymptomatic" infants (aged from birth up to two years) with typical appearing thymus on chest X-ray. The ultrasonic features of the normal gland are described. Moreover, the contribution of ultrasound is illustrated by five cases of partially ectopic thymus and by one case of prominent gland in a teenager. Ultrasound may help in differentiating normal gland from mediastinal masses by defining echogenicity, location and extension.

Choristoma↗