Molecular-dynamics study of the structure, binding energy, and melting of small clusters of fullerene molecules using Girifalco's spherical model.
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Biomedical subjects
Publications and source records attributed to C Rey.
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Several devices are available for transcatheter occlusion of atrial septal defect. This report describes the international experience with the buttoned device. During a 4.5-year period ending in February 1993, 180 transcatheter atrial septal defect occlusions were performed with the buttoned device. Patient age varied between 0.6 and 76 years and stretched atrial defect diameter between 5 and 25 mm. The defects were closed with 25 to 50 mm devices delivered through 8F (148 patients) or 9F (32 patients) sheaths. Twelve patients were adults whose defects were closed to prevent recurrence of cerebrovascular accidents caused by presumed paradoxic embolism. In the remaining patients the atrial defect was closed to treat the left-to-right shunt. The atrial septal defects were effectively occluded as demonstrated by (1) decrease in pulmonary-to-systemic flow ratio from 2.1 +/- 0.6 (mean +/- SD) to 1.05 +/- 0.1 (p < 0.01) by oximetry; (2) normalized S2 and disappearance of the diastolic murmur by auscultation; and (3) improvement in right ventricular volume overloading by echocardiogram. However, trivial to small shunts could be detected by color Doppler studies in 76 (45%) of 168 patients in whom such data are available. Complications included unbuttoning in 13 and whole-device embolization in 1. All patients remained stable, and retrieval of the device and surgical closure of the atrial septal defect were accomplished in 10 patients. Transcatheter retrieval was used in the remaining 4 patients. The incidence of unbuttoning, a major complication of the procedure, appeared to decrease with the increasing experience of the investigators and with device modification (third-generation). The follow-up duration varied between 1 month and 4 years. Six patients required surgery during the follow-up period. In the remaining patients (n = 160), clinical examination did not reveal signs of atrial shunts. Color Doppler studies revealed either complete disappearance of the previously demonstrated shunts or further diminution of their size. The results indicate that transcatheter occlusion of the atrial septal defects with buttoned devices is feasible, relatively safe, and effective, and it appears to be a viable alternative to surgery for some patients with secundum atrial septal defect. Complications are infrequent and should improve with experience.
Conflicting reports concerning the hepatic effects of interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) in the metabolic response to injury led us to investigate the influence of physiological concentrations of these cytokines on amino acid metabolism in the isolated perfused rat liver. IL-1 beta was ineffective at a concentration of 1 ng/mL, whereas TNF alpha (0.7 ng/mL) reduced the uptake of some of the main gluconeogenic amino acids (alanine, -55.3 +/- 4.9 v -72.9 +/- 13.7 nmol.min-1.g-1 in controls, P < .05) without affecting urea synthesis. TNF alpha increased glucose uptake by 237% and inhibited that of free fatty acids (-1.6 +/- 1.4 v -9.9 +/- 6.7 nmol.min-1.g-1 in controls, P < .05). IL-1 beta and TNF alpha potentiated glucagon-induced total amino acid uptake by 56% and 87%, respectively. They also affected glucagon-activated gluconeogenesis, leading to an initial potentiation of glucose release. Thereafter, IL-1 beta inhibited glucagon action, leading to an hepatic uptake of glucose. These results indicate that (1) in the conditions of the study, IL-1 beta has no direct effect on hepatic amino acid exchanges and utilization; (2) TNF alpha which exerted an inhibitory effect on these parameters, could be involved in the reduced amino acid exchanges during the end stage of sepsis; (3) the TNF alpha-induced increase in glucose uptake could be related to an inhibition of gluconeogenesis and/or to the activation of glucose utilization by Kupffer cells; (4) IL-1 beta and TNF alpha both potentiate the action of glucagon on hepatic amino acid uptake and utilization; and (5) complex interactions between Kupffer cells and hepatocytes on the one hand and between cytokines and hormones on the other hand could account for the differences in hepatic metabolism according to the stage of the response to injury.
Hydroxyapatite (HA) surfaces exposed, at room temperature, to various aqueous media of different compositions (distilled water, saline solution, cell culture media, saturated HA solution) have been studied by X-ray photoelectron spectroscopy (XPS) angular analysis and IR reflectance spectroscopy. An important decrease of the Ca/P atomic ratio of the surface layer was seen on all exposed surfaces, reaching 1, the Ca/P ratio of dicalcium phosphate dihydrate (DCPD) for the uppermost surface layer. Furthermore, HPO4(2-) ions were observed by XPS and IR. These chemical changes seem to be related to an equilibration process of the surface independent of the dissolution mechanism. Despite the Ca/P ratio observed, no specific phosphate ion environments, such as that of DCPD, were seen by IR.
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We evaluated the rat cirrhosis model obtained by repeated intraperitoneal administration of CCl4 (group C) with regard to biological and nutritional conditions in comparison to ad libitum (group AL) and pair-fed control rats. Cirrhotic rats were divided into two groups according to their clinical condition: group C1 (n = 4) represented those in good physical condition and group C2 those (n = 10) in poor physical condition. Autopsy indicated that rats in group C2 suffered from severe malnutrition as judged by body weight, carcass weight and the carcass/body weight ratio. However, all 14 treated rats presented the same micronodular cirrhosis and the same alterations in liver function, except for alkaline phosphatase activity (group C1: 110 +/- 63 IU/l, group C2: 259 +/- 110 IU/l; p < 0.05). In the cirrhosis groups, plasma levels of branched-chain amino acids (BCAA) and the BCAA/aromatic amino acid (AAA) ratio were significantly reduced, but values in groups C1 and C2 were not significantly different (BCAA/AAA: 1.9 +/- 0.9 in group C1, 1.5 +/- 0.8 in group C2, 2.8 +/- 0.3 in group AL; C1 and C2, vs. AL: p < 0.05). These alterations were similar to those observed in human cirrhosis and were not solely the result of reduced food intake, as indicated by the lack of difference between pair-fed and ad libitum-fed control rats.
The considerable advances achieved in the field of echocardiography have made this investigation an essential diagnostic tool. Under the auspices of the French Society of Cardiology, the Working group on Echocardiography publishes its practical recommendations for optimising the training of echocardiographers (theoretical instruction and practical courses) and for performing echocardiography (understanding the clinical problem, referral to previous examinations, necessary recordings and measurements, and appropriate equipment). In the future, these recommendations should be updated to take into account continuing technical improvements and changes in methods of studying cardiac disease by echocardiography.
Percutaneous occlusion of patent ductus arteriosus with the double umbrella Rashkind prosthesis is an alternative to surgery. The authors report the results of a series of 40 patients aged 16 to 203 months, who underwent transcatheter occlusion of patent ductus arteriosus between January 1989 and March 1993. These children were followed up regularly, clinically and by echocardiography to determine the presence or absence of a residual shunt. Immediately after implantation, angiography showed a residual shunt in 75% of cases. However, the shunt progressively regressed during follow-up. Three types of shunt were described using colour Doppler based on the diameter of the transductal jet at its origin and its extension in the pulmonary artery: type I, a wide jet (> 3 mm), type II, or minimal shunt, with a jet diameter of 2 to 3 mm and an extension to the pulmonary valve (flame-like), and finally the type III, or punctiform shunt with a jet diameter < 2 mm and extension in the main pulmonary artery < 1.5 cm. During follow-up, a transition between the 3 types was observed in 37% of cases. Kaplan-Meier actuarial analysis showed a residual shunt rate of 33% at one year and 19% at 2 years after implantation. The search for predictive factors of residual shunt showed that very young patients at the time of catheterisation was the only indicator of a residual shunt (p = 0.03). Occlusion of a patent ductus arteriosus with a Rashkind device is a reliable method which gives good results. The essential problem remains that of a residual shunt but this disappears in 3/4 of patients during follow-up. When the shunt persists, a 1 to 2 year interval is advised before considering implantation of a second occluder.
The authors report 4 cases of the scimitar syndrome with pulmonary hypertension by stenosis of an abnormally draining right pulmonary vein and they also review the literature. All cases were symptomatic from infancy. The diagnosis was confirmed by catheterisation which showed a significant pressure gradient between the right pulmonary vein and the inferior vena cava, and by angiography which demonstrated the stenosis. None of the treatments proposed (interventional catheterisation with dilatation and eventual implantation of a stent, surgery with treatment of the stenosis and reimplantation of the right pulmonary vein in the left atrium, or pneumonectomy) were satisfactory. However, it is possible that earlier treatment could be effective as changes in the pulmonary vascular bed seem to occur very early in these patients.
Over a 33 year period, 127 patients under 2 years of age with dilated cardiomyopathies and appearances compatible with the diagnosis of primary endocardial fibroelastosis were admitted to the paediatric cardiac unit of the CHRU of Lille. The average follow-up was 8.9 +/- 6.7 years. Ninety-four children (74%) were cured, 16 (13%) had persistent cardiomegaly and/or left ventricular dysfunction on echocardiographic examination, and only 17 (13%) patients died (10 in the year following their initial hospital admission including 5 in the first week). The outcome of patients was not related to age at diagnosis, sex, cardiothoracic index, initial shortening fraction of the left ventricle or the period at which the patients were seen for the first time. On the other hand, the presence of a family history of cardiomyopathy was associated with a significantly worse prognosis. A recurrence of symptoms was the factor most closely correlated with a bad prognosis: 12 of the 19 patients (63%) with this evolution died, and 4 others (21%) had persistent myocardial dysfunction at the end of the study. These recurrences were often observed after premature withdrawal or after use of ineffective dosages of digitalis. In the authors' experience, dilated cardiomyopathy in neonates with clinical features of primary endocardial fibroelastosis is associated with a relatively high number of cures. Prolonged treatment with high doses of digitalis seems a determining prognostic factor.(ABSTRACT TRUNCATED AT 250 WORDS)
BACKGROUND: Pneumomediastinum is a rare complication of anorexia nervosa. It may occur in patients with severe weight loss and a history of induced vomiting. CASE REPORT: A 14 year-old girl was admitted suffering from severe anorexia nervosa. Shortly after admission, she complained of anterior thoracic pain. Examination showed subcutaneous emphysema of the supraclavicular fossae and the base of the neck. Thoracic X-ray showed pneumomediastinum without pneumothorax. At the time, the patient admitted to a history of surreptitious chronic induced vomiting. Gastrografin esophagography ruled out an oesophageal tear. The pneumomediastinum gradually disappeared over a period of several days with simple clinical and radiological monitoring. CONCLUSIONS: This case, along with seven others reported in the literature, confirms that pneumomediastinum in anorexia nervosa is usually not accompanied by pneumothorax. An oesophageal perforation must always be ruled out. Spontaneous pneumomediastinum invariably has a favorable outcome.
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S-adenosyl-l-methionine (AdoMet) has been reported to affect events linked to noradrenergic neurotransmission. In the present work, we studied the effect of AdoMet on norepinephrine (NE)-stimulated inositol phosphate production in 3H-inositol-labelled crude synaptosomal suspensions of rat brain. AdoMet (50-1000 microM) decreased both the synthesis of labelled polyphosphoinositide (30-50%) and the release of inositol mono- and bisphosphate (40-50%). The AdoMet effect was not dependent on NE concentration (10-1000 microM), suggesting that the inhibition of inositol phosphate release was not the result of a modification of the norepinephrine binding to its receptor sites. S-adenosyl-L-homocysteine (AdoHcy) (1 mM) an inhibitor of methyltransferase activities, partially inhibited (70%) the AdoMet (0.1 mM) effect, indicating that the methylation processes cannot explain all the effects observed. We conclude that, in addition to previously reported effects of AdoMet on NE transport, AdoMet may reduce NE-linked intracellular signalling.
This study examines the relation between signal-averaged electrocardiographic measurements and the occurrence of spontaneous ventricular arrhythmias in 86 patients with a postoperative right bundle branch block after repair of tetralogy of Fallot; special attention was given to the influence of age, body surface area and right ventricular systolic pressure on signal-averaged electrocardiograms. Twenty-eight of the 86 patients had significant ventricular arrhythmias on 24-hour ambulatory monitoring. A positive linear correlation was found between filtered QRS duration and age at evaluation or body surface area (r = 0.45, p = 0.00001; r = 0.54, p < 0.00001, respectively) and between amplitude of the last 40 ms of the filtered QRS and right ventricular systolic pressure (r = 0.48, p < 0.001). A negative linear correlation was found between amplitude of the last 40 ms of the filtered QRS and age at evaluation or body surface area (r = -0.27, p = 0.01; r = -0.34, p = 0.002, respectively). When the age of the patients or the body surface area was considered with an analysis of covariance, the presence of ventricular arrhythmias was associated with a higher amplitude of the last 40 ms of the filtered QRS. In addition, an amplitude of the last 40 ms of the filtered QRS > 170 microV had an excellent sensitivity (100%) and a good specificity (88%) for identifying patients with both right ventricular systolic hypertension and spontaneous ventricular arrhythmia. Thus, adjustment of signal-averaged parameters for age at evaluation and body size is mandatory when studying postoperative tetralogy of Fallot.
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The prevalence of silent HIV-1 infections in subjects at risk of acquiring HIV infection by heterosexual transmission was assessed using a nested polymerase chain reaction (PCR) assay. The two groups of risk subjects consisted of 92 female prostitutes and 43 heterosexual partners of infected individuals. Appropriate positive and negative control persons were included in the study. Serum samples were also tested for antibody to HIV-1 by an enzyme immunoassay (EIA) and positive results confirmed by Western blot. PCR results in the two risk groups and the positive and negative controls were in full agreement with serological results. It is concluded that silent infection with HIV-1 is infrequent in persons at risk for heterosexual transmission.