A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.

Report of a rare testicular teratoid Wilms Tumor in an adult patient

Although primarily a pediatric disease, nephroblastomas (also known as Wilms tumor) occur in adults at a rate of less than 0.2 cases per million per year. Rarer still are teratoid Wilms tumors, which arise from teratomas and therefore can be extrarenal. We describe the sixth recorded case of a testicular teratoid Wilms tumor in an adult patient with accompanying histological images of the specimen. Following the case, there is a brief discussion of the current literature.

Fully versus constrained statistical fragmentation of carbon clusters and their heteronuclear derivatives

The Microcanonical Metropolis Monte Carlo (MMMC) method has been shown to describe reasonably well fragmentation of clusters composed of identical atomic species. However, this is not so clear in the case of heteronuclear clusters as some regions of phase space might be inaccessible due to the different mobility of the different atomic species, the existence of large isomerization barriers, or the quite different chemical nature of the possible intermediate species. In this paper, we introduce a constrained statistical model that extends the range of applicability of the MMMC method to such mixed clusters. The method is applied to describe fragmentation of isolated clusters with high, moderate, and no heteronuclear character, namely, C_nH_m, C_nN, and C_n clusters for which experimental fragmentation branching ratios are available in the literature. We show that the constrained statistical model describes fairly well fragmentation of C_nH_m clusters in contrast with the poor description provided by the fully statistical model. The latter model, however, works pretty well for both C_n and C_nN clusters, thus showing that the ultimate reason for this discrepancy is the inability of the MMMC method to selectively explore the whole phase space. This conclusion has driven us to predict the fragmentation patterns of the C₄N cluster for which experiments are not yet available.

IGLIAS: A new experimental set-up for low temperature irradiation studies at large irradiation facilities

We designed and built a mobile experimental set-up for studying the interaction of ion beams with solid samples in a wide temperature range from 9 to 300 K. It is either possible to mount up to three samples prepared ex situ or to prepare samples by condensation of molecules from gases or vapours onto IR or Visible-ultraviolet (Vis-UV) transparent windows. The physico-chemical evolution during irradiation can be followed in situ with different analysis techniques including Fourier transform infrared spectroscopy, Vis-UV, and quadrupole mass spectrometry.

Detection of atomic and molecular mega-electron-volt projectiles using an x-ray charged coupled device camera

We show that an x-ray charge coupled device (CCD) may be used as a particle detector for atomic and molecular mega-electron-volt (MeV) projectiles of around a few hundred keV per atomic mass unit. For atomic species, spectroscopic properties in kinetic energy measurements (i.e., linearity and energy resolution) are found to be close to those currently obtained with implanted or surface barrier silicon particle detectors. For molecular species, in order to increase the maximum kinetic energy detection limit, we propose to put a thin foil in front of the CCD. This foil breaks up the molecules into atoms and spreads the charges over many CCD pixels and therefore avoiding saturation effects. This opens new perspectives in high velocity molecular dissociation studies with accelerator facilities.

Scaling law for the partitioning of energy in fragmenting multicharged carbon clusters

The complete fragmentation of highly excited and multicharged C(n)(q+) clusters (n=5-10; q=2-4), produced in high velocity collisions of C(n)(+) with atoms, has been measured. Multiplicity distributions are presented and used to deduce, within a statistical framework, the partitioning of energy between the fragments' production and fragments' kinetic energy. This partitioning is found to scale as the charge over mass ratio of the cluster.

Fragmentation of highly excited small neutral carbon clusters

We present a combined experimental and theoretical study of fragmentation of small Cn clusters (n = 5,7,9) produced in charge transfer collisions of fast (nu = 2.6 a.u.) singly charged Cn+ clusters with He. Branching ratios for all possible fragmentation channels have been measured. Comparison with microcanonical Metropolis Monte Carlo simulations based on quantum chemistry calculations allows us to determine the energy distribution of the excited clusters just after the collision.

[The excision of branchial parapharyngeal cysts by transbuccal or l cervical approach]

Branchial cysts located in the parapharyngeal space are extremely rare; only seven cases were described in the literature between 1927 and today. In Quebec City, two cases were operated on during the last 3 years. Often, many antibiotic and surgical treatments have been inefficiently used, before getting to the correct diagnosis and final curative treatment. We stress the importance of a detailed evaluation of the lesion and of a noninvasive surgery. Magnetic resonance imaging is the primary imaging modality for parapharyngeal space masses, and surgical excision using the transoral approach is advantageous in selected cases.

The effect of treatment with angiotensin-converting enzyme inhibitors on survival of pediatric patients with dilated cardiomyopathy

Outcome in 81 pediatric patients with dilated cardiomyopathy was reviewed to assess whether treatment with angiotensin-converting enzyme (ACE) inhibitors affected survival. Age at onset was 3.6 +/- 0.6 years. Twenty-seven children (group 1) were treated with ACE inhibitors. Conventional therapy was used in the remaining 54 patients (group 2). There were no significant differences between the two groups in age at onset, left ventricular shortening fraction, left ventricular end-diastolic pressure, or mean pulmonary artery pressure. Patients treated with ACE inhibitors had a significantly better survival during the first year (p < 0.05) with continuation of this trend throughout the second year (p = 0.06). Beyond 2 years there was a tendency toward better survival in ACE inhibitor-treated patients, but the differences were no longer significant (p = 0.14). These data, along with observations in adult patients with chronic cardiac failure, indicate that converting enzyme inhibitors have a beneficial effect on prolonging survival of infants and children with severe left ventricular dysfunction from dilated cardiomyopathy.

Outcome of infants and children with dilated cardiomyopathy

A review of 81 infants and children with dilated, poorly contracting left ventricles without associated structural abnormalities was undertaken to identify risk factors for poor outcome, which could be used in selecting candidates for cardiac transplantation. Significant atrial or ventricular dysrhythmias, or both, were detected on presentation or during follow-up in 24 patients. Arrhythmias were present in only 8 of 51 survivors (16%) but were detected in 16 of 30 patients (53%) who died (p less than 0.05). Patients dying suddenly were even more likely to have had documented dysrhythmias (8 of 11, p less than 0.05). Left ventricular shortening fraction was similar in survivors and nonsurvivors (14.9 +/- 1.0% vs 15.3 +/- 1.7%). Left ventricular end-diastolic pressure in 44 patients who had cardiac catheterization averaged 20.8 +/- 1.6 mm Hg. Left ventricular end-diastolic pressure was significantly higher in patients who died than in those who survived (29.5 +/- 2.2 vs 15.0 +/- 1.6 mm Hg, p less than 0.001). Analysis of actuarial survival revealed that mortality was highest during the first 6 months after presentation (19% mortality). Survival declined more gradually thereafter and was 70% at 2 years, 64% at 5 years and 52% after 11.5 years. Age at initial presentation did not have any significant impact on survival. However, left ventricular end-diastolic pressure greater than 25 torr was associated with a significantly increased mortality rate (p less than 0.05). Early cardiac transplantation should be considered in patients with markedly elevated left ventricular end-diastolic pressure or complex atrial or ventricular arrhythmias.

Metabolic clearance rate (MCR) of dehydroepiandrosterone sulfate (DS), its metabolism to dehydroepiandrosterone, androstenedione, testosterone, and dihydrotestosterone, and the effect of increased plasma DS concentration on DS MCR in normal women

The combined infusion of [3H]dehydroepiandrosterone sulfate [( 3H]DS) and [14C]estrone (E1) for 6 h in four normal women in the follicular phase of the cycle demonstrated values of 13.77 +/- 0.27 L/day (mean +/- SE) for the DS MCR (MCRDS) and 1343 +/- 206 L/day for MCRE1. The fraction of DS metabolized to dehydroepiandrosterone (D), [rho]DS-D, was 0.285 +/- 0.044, and the fraction of D arising from DS (delta D) was 0.318 +/- 0.096, determined using isotopic techniques. Raising the plasma DS concentration by 8.6 micrograms/mL (23 mumol/L) by infusing DS iv increased the MCRDS to 24.49 L/day in the first subject, and raising the plasma DS by 11.40 +/- 0.33 micrograms/mL (30.94 +/- 0.90 mumol/L) in the next three subjects raised the MCRDS to 35.7 +/- 1.3 L/day (P less than 0.01) without changing the MCRE1. The increase in MCRDS produced by increasing plasma DS makes it difficult to accurately measure the MCRDS in effect at the subject's endogenous plasma DS concentration by infusion of nonisotopic DS. Determination of the fractions of D, androstenedione (delta delta 4A), and testosterone (T) arising from DS using the increase in the plasma concentrations of these steroids produced by infusion of nonisotopic DS gave the following estimates: delta D = 0.262 +/- 0.042, delta delta 4A = 0.089 +/- 0.046, and delta T = 0.273 +/- 0.14.

Usefulness of anticoagulant therapy in the prevention of embolic complications of atrial fibrillation

The medical records of 254 patients with atrial fibrillation were reviewed to determine the incidence of embolic events in relation to type of cardiovascular disease, duration of atrial fibrillation, and use of anticoagulants. During a total follow-up of 833 patient-years in atrial fibrillation, there were 32 instances of systemic embolism: 21 involved the cerebral circulation and 11 were extracerebral. Thirty of these events occurred during 549 patient-years of follow-up without anticoagulation therapy (5.46 of 100 patient-years), while only two embolic events occurred during 284 patient-years on anticoagulants (0.7 of 100 patient-years). Thus, the incidence of embolism was eight times more frequent during the unanticoagulated period of observation in atrial fibrillation (p less than 0.002). The incidence of embolism during follow-up without anticoagulants was the same regardless of the presence or absence of mitral valve disease and regardless of whether atrial fibrillation was chronic or paroxysmal. The rate of serious hemorrhagic complications on anticoagulants was acceptably low (2.11 of 100 patient-years). We conclude that in this study population anticoagulant therapy reduced the risk of embolic complications of atrial fibrillation. The results also indicate that the use of anticoagulants should not be limited to patients with atrial fibrillation due to mitral valve disease.

Electrophysiologic effects of intravenous diltiazem in patients with recurrent supraventricular tachycardias

The electrophysiologic effects of intravenous diltiazem were evaluated in 10 patients with recurrent supraventricular tachycardias. The tachycardia incorporated an accessory pathway in 7 patients and was due to AV nodal reentry in 3 patients. Diltiazem 0.25 mg/kg was administered intravenously over 5 minutes during sustained supraventricular tachycardia. Programmed electrical stimulation was used to restore sinus rhythm if diltiazem failed to terminate the arrhythmia within 10 minutes. Conduction intervals, refractory periods and tachycardia characteristics were evaluated before and immediately after drug administration. Diltiazem did not significantly modify sinus cycle length, AH and HV intervals. Atrial and ventricular effective refractory periods were similar before and after diltiazem. The effective refractory period of the AV node was prolonged by 42 msec after diltiazem (p less than 0.05). Diltiazem increased the tachycardia cycle length from 320 +/- 41 to 353 +/- 36 msec (p less than 0.01) but terminated the arrhythmia in only 2 patients. After diltiazem, supraventricular tachycardia could not be reinitiated in only 2 patients and the tachycardia initiating window was not significantly reduced (56 +/- 26 to 41 +/- 33 msec). The infusion of diltiazem was accomplished without side effects. Thus, 0.25 mg/kg of intravenous diltiazem produces a modest depression of AV nodal function and is not very effective in terminating supraventricular tachycardia or preventing its initiation in this study population. Further studies using higher doses of intravenous diltiazem would be useful to determine its maximal therapeutic benefit in patients with recurrent supraventricular tachycardias.

Comparative diagnostic performance of the Telemed computer ECG program

One thousand consecutive ECG's from an ambulatory population of patients with suspected or proven cardiac disease were evaluated using two versions of the Telemed computerized ECG system. Only minor differences were found between the two programs. In version 6 vs. version 5, 87% vs. 90% of 287 normal ECG's were correctly classified and 93% vs. 96% of abnormal ECG's were correctly classified; the percent of acceptable diagnostic agreement was 86.2% and 87.4% respectively (NS). The sensitivity for arrhythmia detection, transmural inferior infarction and ST-T wave abnormalities was slightly greater in version 6. The increased sensitivity was not accompanied by decreased specificity. The sensitivity for left ventricular hypertrophy decreased from 95.2% to 91.4% in version 6 with a slight increase in specificity (95.2% to 97.0%). In conclusion, criteria changes in the most recent version of the Telemed program have not resulted in a major change in diagnostic performance. Arrhythmia detection is slightly but not significantly improved.

Beneficial effect of intravenous diltiazem in the acute management of paroxysmal supraventricular tachyarrhythmias

We tested the effectiveness and safety of i.v. diltiazem in the management of paroxysmal supraventricular tachyarrhythmias in 39 patients, 21 with organic heart disease and seven in heart failure. Fifteen patients presented with supraventricular tachycardia, 12 with atrial fibrillation and 12 with atrial flutter. End points were conversion to sinus rhythm or slowing of the ventricular rate to 100 beats/min or less. Diltiazem was given as an i.v. bolus of either 150 or 300 micrograms/kg over 2 minutes. A second injection was administered to patients who received the lower dose and failed to reach either end point within 30 minutes. The overall success rate was 82% (32 of 39 patients). Time to end point was 5 minutes or less in 20 patients. Conversion to sinus rhythm occurred in 13 of 15 patients (87%) with supraventricular tachycardia and in two of 12 patients with atrial fibrillation. Treatment side effects included a slow ventricular rate in one patient who had a sick sinus syndrome and hypotension in two patients that rapidly responded to fluid administration. We conclude that i.v. diltiazem is effective and well tolerated and advocate its use in the management of paroxysmal supraventricular tachyarrhythmias.

[Value of the automated analysis of the electrocardiogram by the Telemed program (V version)]

A series of 1000 12 lead ECGs recorded in 1000 consecutive ambulatory patients were analysed by the Telemed (V Version) programme and its interpretation and the precision of the French translation were compared with the interpretation of two physicians using standard criteria. The computer identified 90% of the 285 ECGs coded as "normal" by the physicians, 69% of the 57 ECGs coded as "borderline" and 96% of the 658 ECGs coded as "abnormal". The computer interpretation was correct in 74% of cases and acceptable in 87,4% of cases. The computer classified 80% of the 240 arrhythmias correctly. Atrial fibrillation was detected in 91% of cases, and ventricular and supraventricular extrasystoles in 88% of cases. The recognition of other arrhythmias was not as good but the small number of cases did not allow statistical evaluation. The 148 cases of axis deviation and 98% of ventricular conduction defects were identified. The programme detected 84% of transmural infarcts, the sensitivity being greater for anterior or lateral than inferior infarctions. The majority of undiagnosed infarcts were "possibles" according to the criteria of the Minnesota Code. Of 536 ECGs with ST-T segment abnormalities, 81% were classified correctly; ST depression of less than 0.5 mm comprised the majority of false negatives. The sensitivity of the programme to left ventricular hypertrophy was excellent (95%) with a specificity of only 92,5% as the programme uses the Romhilt-Estes criteria which are more liberal than those of the Minnesota Code. The comparison of the sensitivity and specificity for the commonest ECG changes showed excellent all round diagnostic performance of the Telemed programme. In conclusion, despite the large number of abnormal ECGs, the level of computer-physician concordance was high. The French translation of the V Version of the Telemed programme is therefore suitable for clinical use Nevertheless, the computer interpretation should still be checked by a physician.

Relative bioavailability of three commercial quinidine dosage forms

Bioavailabilities of three quinidine formulations were compared. Two tablets of each dosage form were administered to 12 healthy volunteers according to a repeated Latin square design; plasma levels of unchanged and total drug were determined. Quinidine was absorbed significantly more rapidly from one of the formulations than the other two; the bioavailability of this formulation, calculated from intact drug data, normalized for subject differences, was also significantly greater than that of the other two, 68 and 76 per cent respectively. Individual comparisons of area under the curve (AUC) indicated that estimated relative bioavailability depends on the specificity of the assay, the adjustment of the AUC for the area beyond the last measurable plasma concentration and the normalization of the AUC. The data suggest there is a correlation between dissolution rate and peak plasma concentration.

MB creatine kinase and the evaluation of myocardial injury following aortocoronary bypass operation

Myocardial injury was studied in 104 patients undergoing coronary artery grafting without cold chemical cardioplegia using the quantity of the isoenzyme MB of the creatine kinase liberated as an indicator. This method of evaluation, which is said to permit comparison of different techniques of myocardial protection, allowed us to consider the relative importance of several factors believed to have an influence on intraoperative myocardial injury. Indices of significance were duration of symptoms before operation, presence of chronic arterial hypertension, and the type of antiangina treatment employed. Other operative factors included severity of the arterial lesions, number of anastomoses performed, and duration of extracorporeal circulation and of aortic cross-clamping.

Bioavailability of three commercial sustained-release tablets of quinidine in maintenance therapy

The bioavailability of three quinidine formulations was estimated during a dosing interval at steady state following their administration in 12 selected patients in accordance with a Latin-square 3 x 3. Each subject received the three dosage forms as two tablets every 12 hr for 6 days. Blood and urine samples were taken on the 7th day during the regular 12-hr dosing interval. Unchanged quinidine was determined by a reported spectrofluorometric procedure. The total fluorescence of plasma quinidine and metabolites also was monitored. The data obtained indicate that one dosage form gave a high peak level followed by a fall in the concentration. The two other forms presented a relatively lower peak followed by a plateau and then a decline. The differences between the dose-corrected values of Cp,max were statistically significant. Secondary effects were observed particularly with one dosage form and could be related to the high Cp,max value and/or the high percentage of quinidine liberated rapidly in the GI tract. Blood and urinary data indicated an equivalent degree of absorption. The dissolution behavior of the formulations and their absorption data suggest that there is a correlation between the quantity dissolved at 30 min and Cp,max.

Long term follow-up of aneurysmectomy for recurrent ventricular tachycardia or fibrillation

The success of aneurysmectomy in abolishing recurrent ventricular tachycardia or ventricular fibrillation has not been clearly defined. Ten patients who underwent aneurysm resection to control ventricular arrhythmias were studied before and an average of 19 (4 to 42) months following operation. All patients had moderate to large aneurysms and four had asynergy in adjacent segments. Of four patients with significant stenosis in vessels not supplying the aneurysm, three had aortocoronary bypass grafts in addition to their resection. Ambulatory Holter monitoring and a graded exercise test were performed in all patients postoperatively. There was no operative mortality. Two patients who did not have associated revascularization procedures died suddenly 1.5 and 7 months postoperatively. Of the eight survivors, despite clinical improvement, the Holter ECG revealed runs of ventricular tachycardia in three patients and frequent multifocal ventricular extrasystoles in the other five patients. No correlation was found between recurrence of the ventricular arrhythmias and aneurysm size, contraction pattern of other myocardial segments, extent of coronary disease, or the presence of congestive heart failure. In conclusion, aneurysmectomy does not abolish ventricular tachyarrhythmias and probably should be reserved for patients who remain symptomatic despite an adequate medical trial. The persistence of complex arrhythmias following operation warrants a close follow-up in these patients.

[Mitral prolapse syndrome. Simple diagnosis of forms with severe arrhythmia]

The mitral valve prolapse syndrome encompasses a wide clinical spectrum with a majority of patients presenting with a benign course while a few present with severe arrhythmias. Nineteen patients with a systolic click and angiographic mitral valve prolapse were studied to determine which of several simple tests identified the subgroup with severe ventricular arrhythmias. The incidence and type of ventricular arrhythmias, documented by a 24 hour recording (Holter), were correlated with: 1) cardiac size assessed by the cardiothoracic ratio; 2) echocardiographic indices: end-diastolic septal and posterior wall thickness and left ventricular end-diastolic dimension; 3) a ten minute rhythm strip (mini-Holter). Only patients with ventricular hypertrophy (5 patients) or dilatation (7 patients) had frequent and severe arrhythmias. In these two subgroups, the cardiothoracic ratio was larger than in patients with a normal echocardiogram (7 patients). The ten minute rhythm strip was abnormal in all those patients with severe ventricular arrhythmias (ventricular tachycardia). Thus, in patients with mitral valve prolapse, the presence of an abnormal cardiothoracic ratio, echocardiogram and ten minute rhythm strip identifies patients with potentially severe ventricular arrhythmias. The mechanism of these arrhythmias is still poorly understood; however, a certain number of them may be related to a dysfunction of the autonomic nervous system.

Evaluation of myocardial damage during coronary artery grafting with serial determinations of serum CPK MB isoenzyme

Serial determinations of creatine phosphokinase isoenzymes (CPK) were made during the operative period and the first postoperative week in 60 patients undergoing coronary artery bypass surgery. Electrocardiograms (ECG) and serum levels of glutamic oxaloacetic transaminase (SGOT) and lactic dehydrogenase (LDH) were also evaluated. All patients had increased CPK MB activity which first became detectable during the operative period. The CPK MB curves usually showed a peak during the first postoperative hours and then a rapid decay. Some curves, however, showed a different profile with a prolonged liberation of CPK MB. This type of curve was more frequent in patients with electrical signs of necrosis or ischemic injury. In this group, the total amount of CPK MB released was greater than that in patients with unchanged ECG tracings (p less than 0.05). A mean curve of CPK MB activity was calculated for the patients without electric and/or enzymatic signs of myocardial injury. Serum CPK MB determination is a useful technique for identifying perioperative myocardial infarction (MI) and the time sequence of its occurrence. The appearance of this isoenzyme in every patient undergoing coronary surgery is an interesting finding, and it significance needs to be clarified.

Chlorpromazine-induced electrocardiogram abnormalities

The aim of our clinical investigation was to evaluate the electrocardiographic abnormalities in patients receiving only chlorpromazine, and to assess the role of sex, age and length of illness in these abnormalities. 96 schizophrenic patients (48 male and 48 female patients) satisfying study criteria were selected for inclusion and changed from their old medication to a fixed dose of 125 mg chlorpromazine daily. This uniformization period lasted two weeks, during which the electrocardiograms were taken after an overnight fast. Five patients were excluded because their electrocardiographic changes revealed the possibility of an organic heart disease. The electrocardiograms were found to be normal for 65.9% of the patients and abnormal for 34.1%. 11% of patients were classified as demonstrating Grade I repolarization abnormalities, 14.3% of patients as Grade II, and 8.8% as Grade III. Chi square (X2) tests revealed no significant differences between sexes, age groups or lenghts of illness as regards ECG normality and grade of abnormality.

Vectorcardiographic evaluation of postoperative changes in patients with interatrial septal defect: a review of 55 cases

The pre- and post-operative vectorcardiograms of 55 patients with atrial septal defect (ASD) are discussed. Forty-nine were of ostium secundum type and six of ostium primum type. The criteria used to study the regression of right ventricular hypertrophy were: in the horizontal plane, the ratio of anterior-over-posterior forces, the right-over-left forces and the rotation of the body of the QRS loop; in the frontal plane, the direction of half-area vector. Using these criteria, 46 out of 49 patients with defects of the ostium secundum type had vectorcardiographic evidence of regression of right ventricular hypertrophy. Marked clinical improvement was also demonstrated in all these patients. The three patients in whom improvement was not demonstrated on the vectorcardiogram had persistence of a cardiac defect. Following surgery two children with ostium primum defects showed no change in the frontal plane, whereas in the horizontal plane a normalization of vectorial forces was observed.