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L Lemaitre

Publications and source records attributed to L Lemaitre.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1987

[The Whitaker test. Apropos of an obstacle not to be ignored].

Since 1980, 35 pyelomanometric procedures have been performed in the Department of Clinical Urology for dilatations of the upper urinary tract of uncertain etiology. During two recent procedures, pressure measurements were modified by an extra-urinary obstacle caused by the patient's position. Our experience confirms the value of the Whittaker test as well as the need for a faultless technique.

Adult↗
PubMed1986

[Mycotic aneurysm after catheterization of the umbilical artery].

The finding of an abdominal mass in an 18-month old infant ultimately led to the diagnosis of mycotic aneurysm of a common iliac artery. The lesion was resected and the vessel was ligated. The short and long-term outcome was favourable. The child had been operated upon for cervical teratoma and had undergone catheterization of the umbilical artery complicated with Staphylococcus aureus infection. The presence of a mycotic aneurysm must be suspected in infants with a history of umbilical artery catheterization or neonatal staphylococcal infection, or presenting with a posterior mediastinal or abdominal mass, or arterial hypertension. The vessel most commonly involved is the aorta. Surgical resection, when performed, results in cure. The present case is remarkable on three points: the lesion involved an iliac artery, the diagnosis was delayed and calcifications were present around the aneurysm.

Aneurysm, Infected↗
PubMed1986

An application of impedance techniques to corrosion research on dental amalgam.

AC impedance techniques are finding increasing application in corrosion research. It was our aim to introduce them as a method for the evaluation of the electrochemical behaviour of dental amalgam. The complex plane plots are large depressed semicircles representing the frequency dependence of the impedance and measured at the corrosion potential. Conventional dental amalgams, in a chloride medium, exhibit a current peak in the proximity of -250 mV (vs. SCE). The corresponding impedance spectra are rather complex and difficult to interpret. The high frequency part, however, can be fitted to a semicircle with its centre lying below the real axis. An evaluation of the corresponding 'charge transfer resistance' shows that it is inversely proportional to the corrosion current density.

Corrosion↗
PubMed1986

[Computerized tomography in evaluating the extension of bladder tumors. 215 cases].

CT scan imaging was used to explore 215 cases of bladder tumor (48 A-B1, 55 B2, 85 C, 27 D), and findings compared with those at operation and on histopathology of specimens after total cystectomy (141 cases), partial cystectomy (13 cases) or endoscopic resection (61 cases). The radiologic technique used was that of natural contrast, evaluating the negative contrast of intravesical urine in relation to the normal or pathologic bladder wall. Analysis of scan sections, assisted by a previous pathologic and radiologic study of 14 transverse sections of pelvis, allowed definition of a certain number of semiologic criteria corresponding to the various stages of the disease. Results showed global reliability to be relatively satisfactory for assessment of local and regional extension (85%): it was obviously a more effective investigation for tumors of low invasion (A-B1: 75%, B2: 81%) than for widely infiltrating tumors (C: 94%, D: 93%). Glandular extension was less reliably evaluated, however, since global efficacy was only 65%. Failures observed can be explained by the frequent small size of the metastatic glands, the poorness in cellular and fatty tissues and, particularly, by the fact that the scanner provides data of size of glands only and not on their internal architecture. The place of the scanner among other paraclinical methods of evaluating tumoral extension has still to be determined.

Humans↗
PubMed1985

AC impedance measurements on high copper dental amalgams.

In recent years alloys with a high copper content were developed to improve the corrosion resistance of dental amalgam by elimination of the gamma 2 (Sn-Hg) phase. The purpose of the present investigation was to compare the electrochemical behaviour of high copper amalgams obtained from single composition amalgam alloys (Indiloy; Shofu, Dental Corp., Menlo Park, USA) with those that used the additive mode of copper alloying (Dispersalloy; Johnson & Johnson, East Windsor, USA).

Copper↗
PubMed1985

[Anatomo-clinical and echocardiographic correlations in hypertrophic pyloric stenosis. Apropos of 32 cases].

The authors present diagnosis particularities in 32 cases of hypertrophic pyloric stenosis, from 1980 to 1984, whom 21 cases since 1982 (25 boys, 7 girls). The diagnosis of HPS was confirmed by sonographic and roentgen explorations, isolated or associated: ultrasound alone 3 cases, ultrasound and roentgen combined 29 cases either roentgen first (22) or ultrasound first (7). Fiability was made for 22 cases; two times, error came from false interpretation; eight times were "false negative" results, corrected by roentgenogram, and corresponding with a voluminous pylorus (3) or little, sclerosis pyloric lesions (5). Amelioration of results give, from the last year, right diagnosis in 85 per cent, about 13 cases.

Echocardiography↗
PubMed1984

Massive hemoptysis of pulmonary arterial origin: diagnosis and treatment.

Among 189 patients treated for massive or repeated hemoptysis by transcatheter techniques between 1973 and 1983, a prospective study was attempted between 1979 and 1983 (72 patients) to search for bleeding of pulmonary arterial origin. Among these 72 patients, six were treated by surgical (one) or angiographic (five) occlusion of segmental pulmonary arteries. Pulmonary erosive pseudoaneurysms were seen in five cases (one with intracavitary aspergilloma, two with cavitary tuberculosis, and two with pyogenic abscesses). Among these six cases, one patient died from massive hemoptysis, one from unknown causes, and four are still alive. They are compared with five other patients who died from massive hemoptysis among 117 patients treated only by embolization of their systemic arteries between 1973 and 1979 (one with cavitary tuberculosis, two with intracavitary aspergillomas, one with an abscess of the lung, and one with a necrotic hilar cancer). A pulmonary arterial source of bleeding should be considered in addition to systemic arterial sources in the setting of destructive lung disease.

Aged↗
PubMed1984

[Acute interstitial nephritis and Meckel's diverticulum].

A case of acute haematogenous interstitial nephritis secondary to bacterial infection of a Meckel's diverticulum is reported. The incidence of acute infectious interstitial nephritis with a gastro-intestinal portal of entry is discussed.

Acute Disease↗