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.

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.

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.

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.

[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).

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.

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.

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.

[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.

Bronchogenic carcinoma presenting as a bronchopericardial fistula

A case is reported in which an undiagnosed bronchogenic carcinoma presented clinically with sudden onset shortness of breath and cardiac failure due to the development of an acute bronchopericardial fistula.

Clinical and scintigraphic comparison of silicone and polyvinylpyrrolidone coated silicone perforated plugs

BACKGROUND/AIM

Isolated stenosis of the lacrimal punctum is a frequent cause of epiphora. Treatment relies on surgical opening or dilatation with bi- or monocanalicular prosthesis. Recently, silicone perforated punctum plugs (PPP) were proposed. The drawback with these silicone PPP was that secretions accumulate in the central orifice blocking the spontaneous flow of tears. A modification of the surface of the PPP using polyvinylpyrrolidone (PVP) was thus proposed. The aim was to compare silicone PPP with new PVP surface treated PPP.

METHODS

A prospective study was conducted of 20 patients with dilatable stenosis of the lacrimal puncta who developed epiphora. Epiphora, tolerance, implantation of the PPP, and lacrimal drainage were evaluated using scintigraphy of the lacrimal ducts.

RESULTS

The raw data and statistical analysis showed evidence of a superior performance of PVP surface treated PPP.

CONCLUSION

Long term evaluation of the advantages or risks of PVP plugs and comparison with microsurgical punctoplasty are warranted.

[Disproportion in diameter of the cardiac chambers and great arteries in the fetus. Contribution to the prenatal diagnosis of coarctation of the aorta]

The aim of this study was to identify simple echocardiographic criteria suggesting the presence of coarctation of the aorta in the antenatal period. This was a retrospective cooperative study of 43 cases of foetal echocardiography referred to a paediatric cardiologist for abnormal dimensions of the left cardiac chambers and vessels compared with 102 control foetus. Eighteen (41.8%) had abnormalities of the aortic arch at birth. Thirteen of the 18 (72%) neonates had aortic arch abnormalities when disequilibrium with a small left heart was observed before 25 weeks amenorrhea. The ratio between the right and left ventricular dimensions was abnormally high in foetus with functional disequilibrium similar to the foetus with coarctation: the difference between the two groups was not significant. The ratio of pulmonary artery to aortic dimension was higher in the foetus with coarctation of the aorta than with functional disequilibrium. The difference was significant: p < 0.0001. The diameter of the aortic arch in foetus with a future coarctation was much smaller than the mean of the controls, except in 4 cases. The majority of the foetus without left-sided obstacles at birth had normal aortic arches. An early disequilibrium, a high pulmonary artery/aortic ratio and the small size of the aortic ischmus were the main elements suggestive of abnormalities of the aortic arch, especially in the early prenatal period.

[Late supraventricular arrhythmia complicating Fontan or cavopulmonary type procedures. Apropos of 7 cases]

The authors report 7 cases of late arrhythmias after atriopulmonary (5 cases) or total cavopulmonary (2 cases) bypass procedures. There were 6 cases of atrial flutter and one case of atrial tachycardia. The condition presented with cardiac failure in 5 cases. In 2 patients, atrial flutter caused syncope or dizziness. The arrhythmia was reduced by atrial stimulation (3 cases) or by cardioversion (1 case). Prevention of recurrence with oral amiodarone was effective in all cases but was responsible for secondary effects in 4 cases. In one patient, recurrence of atrial flutter was complicated by right atrial thrombosis with cerebral embolism. Five patients were reoperated after cardiac catheterisation and angiography. Surgery consisted of resection of a stenosis of the anastomosis in one case, and the transformation of atriopulmonary anastomosis into a total cavopulmonary bypass because of a very dilated right atrium without stenosis in 4 patients. The immediate postoperative period was complicated by a recurrence of the arrhythmia in 3 children not treated by antiarrhythmic therapy. At long-term, one patient died 6 months after withdrawal of amiodarone therapy of recurrence of atrial flutter. Five of the 6 survivors are treated with amiodarone or a betablocker; 3 have had pacemaker implantation for severe bradycardia. Late atrial arrhythmias complicating atrio- and cavopulmonary bypass procedures carry a risk of cardiac failure and sudden death. When diagnosed, the patient should be investigated for stenosis of the anastomosis but severe dilatation of the right atrium is often the only finding. After restoration of sinus rhythm, maintenance antiarrhythmic therapy should be continued indefinitely.

[Hypoplasia of abdominal aorta, rare cause of hypertension in childhood]

BACKGROUND

The majority of children with secondary hypertension have a renal abnormality or renovascular lesions. Coarctation of the aorta is also a classical cause, rarely located to the abdominal aorta.

CASE REPORTS

Two girls, 11 and 12 years-old, were suspected of having recent sustained hypertension. Pulsed-wave doppler ultrasonography and angiography showed abdominal aortic hypoplasia associated with renal artery stenosis, unilateral in one patient and bilateral in the other. Both patients became normotensive 10 and 18 months, respectively, after corrective vascular surgery.

CONCLUSION

Examination of the abdominal part of the aorta is mandatory in all patients with hypertension.