Biomedical subjects
Publications and source records attributed to P Simon.
We consider the universality class of the two-dimensional tricritical Ising model. The scaling form of the free energy leads to the definition of universal ratios of critical amplitudes which may have experimental relevance. We compute these universal ratios by a combined use of results coming from perturbed conformal field theory, integrable quantum field theory, and numerical methods.
OBJECTIVE: The revised Edwards-Duromedics valve was introduced onto the market in June 1990. In September 1993, the producer changed the name of the valve to TEKNA, which is a low profile, bileaflet, mechanical prosthesis with a self-irrigating hinge mechanism. The results of a prospective follow-up study after valve replacement with this prosthesis are presented. METHODS: From November 1990 to December 1996, 173 TEKNA prostheses were implanted in 161 patients (73 men, 88 women), either in the aortic (AVR; 48.4%), mitral (MVR; 44.1%), or aortic and mitral positions (DVR; 7.5%). Patient ages ranged from 17 to 83 years (mean age 59.2 +/- 8.7 years). Follow-up was 97.5% complete, comprising 433.15 patient-years for a mean follow-up of 34.8 +/- 23 months. RESULTS: Overall operative (30-day) mortality was 4.97%. Fifteen patients died in the late period, corresponding to a linearized late mortality rate of 3.5%/pt-yr. Actuarial survival at six years was 75.3% +/- 6.2% overall. The actuarial freedom from complications was calculated as follows (linearized rates in parentheses): valve-related mortality 91.3% +/- 5.1% (0.92%/pt-yr); thromboembolism 94.2% +/- 2.5% (1.62%/pt-yr); valve thrombosis 98.6 +/- 1.0% (0.46%/pt-yr); bleeding events 85.9% +/- 4.7% (2.77%/pt-yr); prosthetic valve endocarditis 98.6 +/- 0.9% (0.46%/pt-yr); nonstructural dysfunction 93.2 +/- 3.2% (1.38%/pt-yr); reoperation 87.1 +/- 5.3% (2.08%/pt-yr). Functional class according to NYHA was improved from preoperatively 72.05% in III or IV to 6-year postoperative 94.2% in I or II. CONCLUSION: The clinical performance of the TEKNA valve is quite satisfactory, with low incidence of valve-related complications. No structural deterioration has been observed. Further, the patients physical ability and quality of life were significantly improved.
PURPOSE: This study compared the occlusal relationships after open or closed treatment for fractures of the mandibular condylar process. PATIENTS AND METHODS: A total of 137 patients with unilateral fractures of the mandibular condylar process (neck or subcondylar), 77 treated closed and 65 treated open, were included in this study. Standardized occlusal photographs obtained at several postsurgical time intervals were examined and scored by a surgeon and an orthodontist. Standard statistical methods were used to assess differences between groups. RESULTS: Patients treated by closed techniques had a significantly greater percentage of malocclusion compared with patients treated by open reduction, in spite of the fact that the initial displacement of the fractures was greater in patients treated by open reduction. CONCLUSIONS: Based on this study, more consistent occlusal results can be expected when fractures of the mandibular condylar process are treated by open reduction.
Autosomal dominant polycystic kidney disease (ADPKD) exhibits a genetically heterogeneous transmission involving at least three different genes. PKD1 gene linked mutations are responsible for the disease in about 85% of ADPKD cases. The search for mutations is a very important step in understanding the molecular mechanisms underlying ADPKD. We undertook this study using denaturing gradient gel electrophoresis (DGGE), after a stage of long range PCR, to scan for mutations in the duplicated region of the PKD1 gene in French ADPKD families. This allowed us to identify eight novel mutations and several polymorphisms: among the mutations, three are nonsense mutations, two are deletions in the coding sequence leading to frameshift mutations, one is a splice mutation and two are highly probable missense mutations. In this paper, we also provide a review of the mutations reported so far which are widespread throughout the gene. Although no clear hot spot for mutation is apparent, we will focus on some clustering observed.
PURPOSE: This study assessed the surgical complications after open treatment for fractures of the mandibular condylar process. PATIENTS AND METHODS: A total of 178 patients with unilateral fractures of the mandibular condylar process, 85 treated closed and 93 treated open, were included in this study. A tabulation of surgical findings and intraoperative and postoperative complications was prospectively performed. Standardized animating facial photographs were obtained at several postsurgical intervals and were examined and scored by a prosthodontist and an orthodontist for signs of facial nerve palsy and the quality of the surgical scar. Standard statistical methods were used to assess differences between open and closed treatment groups. RESULTS: There were very few intraoperative or postoperative complications. At the 6-week point, 17.2% of patients treated open had some weakness of their facial nerve. This had resolved by 6 months. The scars were judged either wide or hypertrophic in 7.5% of cases. CONCLUSIONS: Based on this study, surgical complications of open treatment of condylar process fractures that lead to permanent dysfunction or deformity are uncommon.
Explore the source record for details and available documents.
Deep infiltrating endometriosis (deeper than 5 mm under the peritoneum) often takes the form of a nodular lesion (or 'adenomyotic nodule') consisting of smooth muscles and fibrosis with active glands and scanty stroma. Thus, among endometriotic lesions, a certain distinction is drawn between musculo-glandular lesions and glandular lesions composed of endometrial-like epithelium surrounded by a cell-producing (cytogenous) stroma. The aim of this study was to detect by immunohistochemistry, with a monoclonal antibody against muscle-specific actin, the presence of smooth muscles in 54 endometriotic lesions originating from four different pelvic locations (peritoneum, ovary, rectovaginal septum and uterosacral ligaments) and to quantify the smooth muscle content. Smooth muscles were frequent components of endometriotic lesions in pelvic locations. In addition, smooth muscles were significantly (P < 0. 001) more abundant in endometriotic lesions than in their respective unaffected sites. This finding supports, at least partially, the occurrence of a metaplastic phenomenon in the pathogenesis of endometriotic lesions. The definition of distinct endometriotic entities based on the difference in the tissue composition of the lesions (endometriotic nodules versus adenomyotic nodules) is inconsistent with the very frequent presence of smooth muscle cells in endometriosis irrespective of its localization.
In-vitro fertilization (IVF) and ovarian stimulation are frequently performed in patients with endometriosis. Although endometriosis is a hormone-dependent disease, the rate of IVF complications related to endometriosis is low. We report four cases of severe digestive complications due to the rapid growth of sigmoid endometriosis under ovarian stimulation. In three patients, sigmoid endometriosis was diagnosed at laparoscopy for sterility. Because of the absence of digestive symptoms or repercussion on the bowel, no bowel resection was performed before ovarian stimulation. All patients experienced severe digestive symptoms during ovarian stimulation, and a segmental sigmoid resection had to be performed. Analysis of endoscopic and radiological data demonstrated that bowel lesions of small size may rapidly enlarge and become highly symptomatic under ovarian stimulation. At immunohistochemistry, these infiltrating lesions displayed high populations of steroid receptors and a high proliferative index (Ki-67 activity), suggesting a strong dependence on circulating ovarian hormones and a potential for rapid growth under supraphysiological oestrogen concentrations. Clinicians should be aware of this rare but severe digestive complication of ovarian stimulation. The early diagnosis of such lesions may help the patients to avoid months of morbidity falsely attributed to ovarian stimulation side effects. Further experience is necessary to determine the optimal attitude when diagnosing a small and asymptomatic endometriotic bowel lesion before ovarian stimulation.
The histological relationships between fibrotic tissue, endometriotic foci and nerves in the rectovaginal septum endometriotic or adenomyotic nodule were studied. This is considered to be one of the most severe forms of deep endometriosis. Masson's trichrome staining for fibrosis detection and immunohistochemistry with the S100 monoclonal antibody for nerve detection were performed in 28 rectovaginal endometriotic nodules from patients presenting with severe dysmenorrhoea and deep dyspareunia (23 patients with no other endometriotic location or potential cause of pain at laparoscopy and ultrasonography; five patients with multiple pelvic endometriotic localizations and other potential causes of pain at laparoscopy). Patients were allocated to two groups on the basis of their preoperative pain scores for pelvic pain, dysmenorrhoea and deep dyspareunia (group 1, score >7; group 2, score < or =7). For each symptom, the mean number of nerves and endometriotic lesions per high-power field and the mean largest diameter of the lesions were not statistically different in groups 1 and 2. The mean percentages of nerves located within the fibrosis of the nodule and within endometriotic lesions were significantly higher in group 1 than in group 2. Among nerves located within endometriotic lesions, there was a significantly higher proportion showing intraneurial and perineurial invasion by endometriosis in group 1 than in group 2. In rectovaginal endometriotic nodules, there was a close histological relationship between nerves and endometriotic foci, and between nerves and the fibrotic component of the nodule. We postulate that such topographical relationships could at least partially explain the strong association between this lesion and pain.
Explore the source record for details and available documents.
A genome-wide linkage disequilibrium (LD) map was generated using microsatellite genotypes (284 autosomal microsatellite loci) of 581 gametes sampled from the dutch black-and-white dairy cattle population. LD was measured between all marker pairs, both syntenic and nonsyntenic. Analysis of syntenic pairs revealed surprisingly high levels of LD that, although more pronounced for closely linked marker pairs, extended over several tens of centimorgan. In addition, significant gametic associations were also shown to be very common between nonsyntenic loci. Simulations using the known genealogies of the studied sample indicate that random drift alone is likely to account for most of the observed disequilibrium. No clear evidence was obtained for a direct effect of selection ("Bulmer effect"). The observation of long range disequilibrium between syntenic loci using low-density marker maps indicates that LD mapping has the potential to be very effective in livestock populations. The frequent occurrence of gametic associations between nonsyntenic loci, however, encourages the combined use of linkage and linkage disequilibrium methods to avoid false positive results when mapping genes in livestock.
BACKGROUND AND AIM OF THE STUDY: Objective Performance Criteria (OPC) were established to compare a new heart valve prosthesis with fixed standards of linearized complication rates for morbid events: thromboembolism, thrombosis, hemorrhage, leakage and endocarditis. Although the pulmonary autograft operation provides optimal hemodynamic performances, the morbidity of both the autograft and homograft remain topics of controversy. METHODS: Valve-related morbid events and echocardiography in 109 patients who have undergone the Ross operation since 1991 were evaluated at annual follow up examination (mean 2.8 years; range: 1 month to 8 years). Linearized rates (number of events per 100 years patient exposure) were calculated to establish the safety and efficacy of this operation (288.7 years cumulative patient-years). RESULTS: Three patients died perioperatively (2.8%); two patients were reoperated due to autograft incompetence (1.8%, both valve repairs). No patient is currently on anticoagulation therapy, and no events of thromboembolism, valve thrombosis or bleeding were observed during follow up. Two patients had homograft endocarditis but were asymptomatic with moderate incompetence at the last follow up examination. There was no significant increase in aortic incompetence (AI) or pulmonary incompetence (PI) between discharge and follow up (AI, 0.4 +/- 0.5 versus 0.6 +/- 0.6; PI, 0.2 +/- 0.4 versus 0.4 +/- 0.6). In comparing the OPC (events per patient-year) for the Ross operation with those for tissue and mechanical valves, the results were: thromboembolism 0% (tissue 2.5%, mechanical 3%), valve thrombosis 0% (0.2% and 0.8%), all bleeding 0% (1.4% and 3.5%), major bleeding 0% (0.9% and 1.5%), all leakage 0.7% (1.2% and 1.2%), major leakage 0.7% (1.2% and 1.2%) and endocarditis 0.7% (1.2% and 1.2%). CONCLUSION: The pulmonary autograft procedure provides optimal hemodynamics and echocardiographic performance, and low valve-related complication rates; thus, the OPC for tissue and mechanical heart valve prostheses can be fulfilled by this technically demanding operation. These results confirm that the autograft is an ideal aortic valve replacement device.
Etonorgestrel is provided in an subcutaneous implant to assure a contraception of long duration. This progestogen derived from desogestrel already used in several combined oral contraceptives acts by inhibiting ovulation and modifying the viscosity of the endocervical mucus. The contraceptive effect is rapidly obtained after insertion. After removal of the implant, the serum concentration of etonorgestrel rapidly drops down so that most patients ovulate after 3 weeks. The most important side effect of this contraceptive device is the bleeding irregularity encountered in a minority of patients (frequent or prolonged bleedings).
BACKGROUND AND AIM OF THE STUDY: Mitral valve reconstruction in patients with acute endocarditis (AE) is a challenging operation which prompts the surgeon into immediate action. This report summarizes the mid-term results of 22 patients who required mitral valve reconstruction due to AE. METHODS: Mean patient age was 46 years (range: 20-79 years); mean follow up was 46 months (range: 1-90 months). Preoperatively, >70% of patients had severe mitral regurgitation and were in NYHA functional class III. Surgical techniques used were annuloplasty (n = 16; 10 with Carpentier ring, five Wooler-Kay and one Frater); suture closure of the perforation (n = 1), patch closure of the perforation (n = 5), leaflet resection with primary closure (n = 2), leaflet resection with patch closure (n = 8), and chordal transfer (n = 3). Additional surgery included CABG (n = 3) and De Vega plasty (n = 4). Aortic valve replacement or reconstruction (n = 9) included one mechanical valve, one bioprosthesis, one reconstruction and six homografts. Patients were followed up annually in our outpatient department and/or by questionnaires. RESULTS: Two patients died perioperatively due to either low output syndrome or uncontrolled sepsis. There were three reoperations; two of these were successful, and one patient subsequently died. In addition, one patient died six years after operation due to prostatic cancer, and one seven years later due to progressive heart failure. At the last follow up, 15 patients were in NYHA class I (68%) and five in class II (23%); no or only mild mitral insufficiency was seen on transthoracic echocardiography (91%). The estimated survival rate at 60 months was 87 +/- 12.7%, and 12 patients were followed up for >60 months. No incidence of recurrent valve infection occurred. CONCLUSION: Mitral valve reconstruction in patients with AE shows a low incidence of valve-related complications with promising postoperative functional results and mid-term survival. On this basis, mitral valve reconstruction for mitral insufficiency secondary to AE may be recommended as a valve salvage treatment, when it is technically possible.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
An on-line sample treatment method to determine 1-hydroxypyrene (1-OHP), a metabolite of polycyclic aromatic hydrocarbons (PAHs), in human urine has been developed. The hydrolysed biological fluid was directly injected into the chromatographic system after only centrifugation. A miniature precolumn loop packed with a preparative phase and coupled on-line to a liquid chromatographic (LC) system was used for analyte enrichment. The analytes were non-selectively desorbed with the LC eluent and cleaned by means of a column-switching procedure comprising two purification columns and an analytical column. Pre-treatment and analysis were performed within 2 and 20 min, respectively. Average 1-OHP recovery reached 99% in the 1-25 microg/l range of urine, and the quantitation limit was 20 ng/l for 100 microl of injected sample. A comparison with a more time-consuming off-line method was performed by analysing 120 urine samples of PAH-exposed and expected unexposed workers; the statistical treatment indicated that both methods are in agreement.
We previously mapped a quantitative trait locus (QTL) affecting milk production to bovine chromosome 14. To refine the map position of this QTL, we have increased the density of the genetic map of BTA14q11-16 by addition of nine microsatellites and three single nucleotide polymorphisms. Fine-mapping of the QTL was accomplished by a two-tiered approach. In the first phase, we identified seven sires heterozygous "Qq" for the QTL by marker-assisted segregation analysis in a Holstein-Friesian pedigree comprising 1,158 individuals. In a second phase, we genotyped the seven selected sires for the newly developed high-density marker map and searched for a shared haplotype flanking an hypothetical, identical-by-descent QTL allele with large substitution effect. The seven chromosomes increasing milk fat percentage were indeed shown to carry a common chromosome segment with an estimated size of 5 cM predicted to contain the studied QTL. The same haplotype was shown to be associated with increased fat percentage in the general population as well, providing additional support in favor of the location of the QTL within the corresponding interval.