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Biomedical subjects

N David

Publications and source records attributed to N David.

At least 19 recordsLinked to original sources
PubMed2006

[Diagnosis of flat epithelial atypia (FEA) after stereotactic vacuum-assisted biopsy (VAB) of the breast: What is the best management: systematic surgery for all or follow-up?].

OBJECTIVE: FEA lesions group two histological types: columnar cell hyperplasia with atypia (CCHA) and columnar cell change with atypia (CCA). The increasing use of VAB has resulted in increased detection of isolated FEA lesions. The aim of this study was to define the best management possible for these patients: which cases may not need excision? MATERIAL AND METHODS: From our database of 780 VABs carried out from 2000 to 2004, 59 patients with FEA were diagnosed. Cases in which no surgery was performed or all features were not available were excluded, thus excluding 19 cases. Forty patients with FEA were included. We reviewed clinical and mammographic characteristics, histological biopsy, and the corresponding surgically excised tissue features. RESULTS: VAB yielded 25 cases of CCHA and 15 cases of CCA. Surgery revealed seven ductal carcinoma cases (four invasive, three in situ); nine benign lesions, and 24 with atypia (19 FEA and six atypical ductal hyperplasia). We found two features related to the risk of cancer: the presence and the size of hyperplasia. All carcinomas were found within the CCHA lesions. No cancer was yielded when size was less than 10 mm within CCA lesions and lesions that were totally removed. CONCLUSION: We recommend surgical excision when CCHA greater than 10 mm is found on the VAB or it is incompletely removed. CCA lesions or CCHA less than 10 mm or totally removed may obviate systematic surgery.

Biopsy, Needle↗
PubMed2005

Effects of polarization on inverse Bremsstrahlung heating of a plasma.

A molecular dynamic (MD) code is used to compare the rates of heating by inverse Bremsstrahlung (IB) for circularly and linearly polarized radiation. For low intensities the heating rate is found to be independent of polarization. However, at higher intensities the variation of the heating rate with the radiation intensity is found to exhibit a sharper peak for circularly polarized than linearly polarized radiation. This difference is explained in terms of differences in the variation of the electron quiver speed during the optical cycle for linearly and circularly polarized radiation. An analytical expression--which includes a term which is nonlinear in the density of the plasma--for the rate of IB heating is fitted to the rates calculated by the MD code.

Journal Article↗
PubMed2004

Molecular-dynamic calculation of the inverse-bremsstrahlung heating of non-weakly-coupled plasmas.

A molecular dynamic (MD) code is used to calculate the inverse bremsstrahlung (IB) heating rates of a plasma as a function of density and laser intensity. The code belongs to the class of particle-particle-particle-mesh codes. Since the equations solved by the MD code are fundamental, this approach avoids several assumptions which are inherent to alternative methods, for example those which employ a Coulomb logarithm, and is not restricted to weakly coupled plasmas. The results of the MD code are compared to previously published results for plasmas of low coupling. The results of calculations for dense, moderately coupled plasmas are also presented. An analytic expression for the IB heating rate, based on a fit to the rates calculated by the MD code, is suggested. This expression includes terms nonlinear in the plasma density.

Journal Article↗
PubMed2003

Molecular-dynamic calculation of the relaxation of the electron energy distribution function in a plasma.

A molecular-dynamic (MD) code is used to calculate the temporal evolution of nonequilibrium electron distribution functions in plasmas. To the authors' knowledge, this is the first time that a molecular-dynamic code has been used to treat this problem using a macroscopic number of particles. The code belongs to the class of P3M (particle-particle-particle-mesh) codes. Since the equations solved by the MD code are fundamental, this approach avoids several assumptions that are inherent to alternative methods. For example, the initial energy distribution can be arbitrary, and there is no need to assume a value for the Coulomb logarithm. The advantages of the MD code are illustrated by comparing its results with those of Monte Carlo and Fokker-Planck codes with a set of plasma parameters for which the Fokker-Planck calculation is shown to give incorrect results. As an example, we calculate the relaxation of the electron energy distribution produced by optical field ionization of a mixed plasma containing argon and hydrogen.

Journal Article↗
PubMed2002

Dilated coronary sinus in prenatal echocardiography; identification, associations and outcome.

The dilated coronary sinus (DCS) has only recently been clearly visualised in the fetus due to progress in prenatal echography. This is a retrospective study of 22 fetuses presenting with DCS revealed by prenatal echography. We report the circumstances leading to the detection of a DCS and the neonatal outcome of these fetuses. The coronary sinus was defined as dilated depending on its visualisation in cross-section from the '4 chamber' view, as well as a pseudo inter-atrial septal defect from a more posterior view. In each case the gestational age, circumstances of detection, associated anomalies and postnatal outcome are reported. The circumstances were: evaluation of a clearly identified DCS in four cases and during detailed fetal echocardiography because of suspected congenital heart disease in 18 cases. Five cases were associated with a cardiac anomaly, three with an extracardiac anomaly, six with both cardiac and extracardiac anomaly and eight were isolated. Postnatal outcome was related to the associated anomaly. In conclusion, it is important that the echography image be correctly interpreted, as a DCS often implies possible associated defects and therefore affects prognosis. When not associated with other anomalies this condition is not considered serious.

Coronary Vessels↗
PubMed2001

Plasma cell balanitis of Zoon: response to Trimovate cream.

Our objective was to evaluate the response to Trimovate cream in patients with Zoon's balanitis. Patients attending the penile dermatosis clinic between October 1996 and October 1999 with the clinical and histological features diagnostic of Zoon's balanitis were included in this study. They were treated with Trimovate cream for a varying length of time according to clinical response, having declined circumcision as first-line treatment. All cases had photographs taken before and after treatment. Ten cases of histologically-confirmed Zoon's balanitis were treated. Clinical resolution was observed in all cases, all of whom remain on long-term follow-up. In conclusion, topical Trimovate cream is an effective treatment for Zoon's balanitis.

Adult↗
PubMed2001

[Ethmoid adenocarcinomas: retrospective study of 76 patients].

From the retrospective study of 76 adenocarcinomas of the ethmoid sinuses, results were expressed in two terms: the morbidity related to surgery and the oncologic outcome. This case study extends between 1975 and 2000. It includes 71 men and 5 women, with an average of 61 years. 81% of them works in wood dust, with a mean duration of exposure of 26 years. The diagnosis of adenocarcinoma is realized in the three months after the first signs, essentially rhinologicals, next neurologicals and ophthalmologicals. The majority of tumors were classified as T3N0M0, i.e. 57.89%. The treatment of this tumors is surgical: 34.2% surgical only and 59.2% with radiotherapy. The transfacial approach (paralateronasal and degloving) and the combined surgery are respectively performed in 36 patients and 35 patients. 23.2% patients had a local recurrence, and 10% developed cervical nodes and systemic metastasis. Survival rate based on the Kaplan-Meier actuarial method is 82% at 3 years, 80% at 5 years, 72% at 10 years. The prognosis of ethmoidal cancer is strictly correlated to local control. Local recurrence is statistically more likely in patients with involvement of the dura, brain and sphenoid sinus. With the analysis of the carcinologics results, we discuss the therapeutics indications of the adenocarcinomas and a new classification. Taking in account the involvement of the dura, sphenoid and orbit. We did not find any statistical differences between T3 patients treated by combined approach (n = 13) or by transfacial approach (n = 15).

Actuarial Analysis↗
PubMed2000

Dipyridamole and exercise SPET provide different estimates of myocardial ischaemic areas: role of the severity of coronary stenoses and of the increase in heart rate during exercise.

In patients unable to perform a maximal exercise test, dipyridamole single-photon emission tomography (SPET) has a higher capacity than exercise SPET to detect coronary artery disease (CAD). However, in patients with myocardial ischaemia who are able to perform a maximal exercise test, it is not known whether these two tests may be equally used to assess the areas of myocardial ischaemia. This study was aimed at comparing the results provided by dipyridamole and exercise SPET in CAD patients with documented exercise myocardial ischaemia. Forty CAD patients who had undergone exercise thallium-201 SPET and who had myocardial ischaemia documented by an unequivocally positive exercise test underwent an additional 201Tl SPET study after dipyridamole infusion and low-level (40 W) exercise. The extent of defects was compared between the two tests and predictors of discrepant results were sought among data from exercise testing and coronary angiography. The extent of SPET defects was equivalent between the two tests in only 11 patients (28%), larger defects being observed with exercise in 18 [average difference: 12%+/-5% of left ventricle (LV)] and with dipyridamole in 11 (average difference: 15%+/-11% of LV). The best independent predictors of discrepancies between the two tests were: (1) increase in heart rate at exercise SPET, with defects being smaller at exercise than after dipyridamole in none of the patients with an increase >60 bpm (0/14), but in 42% of the others (11/26; P=0.004); and (2) an ischaemic territory related to a <70% coronary stenosis, for which SPET defects were always induced at exercise (10/10) but in only 30% (3/10) with dipyridamole (P=0.0004). Exercise and dipyridamole SPET provide different estimates of myocardial ischaemic areas. Dipyridamole allows the unmasking of perfusion abnormalities in patients who have low increases in heart rate at exercise SPET. However, dipyridamole is also much less efficient at inducing perfusion abnormalities in the ischaemic areas supplied by coronary stenoses of intermediate severity at rest angiography.

Coronary Angiography↗
PubMed2000

Value of bone scintiscan for diagnosis of arterial prosthesis infection: preliminary results.

Diagnosis of arterial prosthetic infection is often difficult to confirm. Several cases of lower extremity hypertrophic osteoarthropathy (HOA) have been associated with arterial prosthetic infection. The presence of bone and joint abnormalities could constitute an early sign of HOA. The purpose of this prospective study was to determine the diagnostic value of routine bone scintiscan in patients hospitalized for suspected arterial prosthesis infection. Between December 1995 and May 1997, 17 patients with suspected infection were admitted to our institution. All underwent bone scintiscan before surgical treatment. Presence or absence of infection was defined according to the criteria proposed by Yeager. During the same period, bone scintiscan was performed in a control group of 8 patients with arterial prostheses but no clinical or laboratory signs of infection. Scintiscans were studied to detect bone and joint abnormalities distal to the arterial prosthesis. The results of this preliminary study indicate that routine bone scintiscan can assist definitive diagnosis in patients with suspected arterial prosthesis infection. Demonstration of bone and joint abnormalities distal to a prosthesis appears to be a fairly sensitive and highly specific sign of infection.

Aged↗
PubMed1999

[Microdeletion of 22q11 and conotruncal cardiopathies: contribution of prenatal diagnosis].

OBJECTIVE: We report our experience on prenatal diagnosis of 22q11 deletion by fluorescent in situ hybridation (FISH). PATIENTS AND METHODS: From February 1997 to April 1998, prenatal diagnosis of 22q11 deletion was performed in 13 cases of congenital conotruncal heart defects. FISH was carried out using D22S75 DiGeorge's chromosome region probe. RESULTS: Microdeletions of 22q11 were detected in 4 fetuses with tetralogy of Fallot (3 cases) and pulmonary atresia with ventricular septal defect (1 case). Termination of pregnancy was performed in two cases for severe congenital heart defect. A third malformed fetus died immediately after a blood sampling procedure. The last fetus, with a tetralogy of Fallot malformation, was born and underwent corrective cardiac surgery. The dysmorphic features of this fetus was suggestive of DiGeorge's syndrome, and the development status was normal. CONCLUSION: Prenatal detection of 22q11 only played a minor role in the decision to terminate the pregnancy in our study.

Chromosomes, Human, Pair 22↗