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Biomedical subjects

M Perrin

Publications and source records attributed to M Perrin.

At least 37 records · Page 2Linked to original sources
PubMed2001

Phase transition in a radiation-matter interaction with recoil and collisions.

The standard model introduced to describe the collective atomic recoil of an ensemble of atoms interacting with a strong electromagnetic field has been here extended by the inclusion of collisions with a buffer gas. As a result, we find that in the thermodynamic limit the coherent emission of radiation exhibits a continuous phase transition upon increasing the pump intensity. The output laser field is strictly larger than 0 only above a critical value. We find that the transition is not associated with the onset of spatial ordering but rather with the onset of a synchronization between the polarization phase and spatial position. A coherence parameter is introduced to characterize the phase transition.

Journal Article↗
PubMed2001

[Superficial venous thrombosis of the lower limbs: prospective analysis in 100 patients].

OBJECTIVES: Our objectives were first to estimate the potential gravity of superficial venous thrombosis (SVT) of the lower limbs by determining the frequency of associated deep venous thrombosis (DVT), pulmonary embolism (PE) and extensions of the junction or a perforating vein and second to identify factors of risk (neoplasia, thrombophilia, connective tissue disease, thromboembolic events). METHOD: We conducted a prospective study in 100 cases of SVT in 88 patients with varicose veins (VV) and 12 patients without varicose veins (NVV). RESULTS: Superficial venous thrombosis was identified in 32 cases (32%): muscle vein in 23 (gastrocnemius, solesu), popliteo-femoro-iliac system in 5, and posterior tibial or fibular vein in 4. In 17 cases (17) the SVT extended to deep veins at distant localizations in 15 (15%). Pulmonary embolism was suspected clinically in 10 cases (10%) and confirmed in 3 (3%). An extension to the saphenous junction was observed in 17 cases (17%) and the thrombus migrated into a deep vein in 7. There were 6 cases of a unique extension to a perforating vein. Search for etiology was conducted in 86 cases: 64 were negative (74.4%), there was a neoplasia context in 5 (6%) and a hemostasis disorder in 17 (19.8%) including 6/12 (50%) in the NVV group and 11/74 (15%) in the VV group. CONCLUSION: Superficial venous thrombosis is often considered to be benign although severe situations can occur in patients with a hemostatis disorder. Consideration of these different factors (risk factors, presence of a deep venous thrombus or pulmonary embolism) should be helpful in determining the etiology and for a better choice of a therapeutic option (medical/surgical) depending on the different subpopulations identified.

Activated Protein C Resistance↗
PubMed2000

Distribution of mRNAs encoding CRF receptors in brain and pituitary of rat and mouse.

Two G protein-coupled receptors have been identified that bind corticotropin-releasing factor (CRF) and urocortin (UCN) with high affinity. Hybridization histochemical methods were used to shed light on controversies concerning their localization in rat brain, and to provide normative distributional data in mouse, the standard model for genetic manipulation in mammals. The distribution of CRF-R1 mRNA in mouse was found to be fundamentally similar to that in rat, with expression predominating in the cerebral cortex, sensory relay nuclei, and in the cerebellum and its major afferents. Pronounced species differences in distribution were few, although more subtle variations in the relative strength of R1 expression were seen in several forebrain regions. CRF-R2 mRNA displayed comparable expression in rat and mouse brain, distinct from, and more restricted than that of CRF-R1. Major neuronal sites of CRF-R2 expression included aspects of the olfactory bulb, lateral septal nucleus, bed nucleus of the stria terminalis, ventromedial hypothalamic nucleus, medial and posterior cortical nuclei of the amygdala, ventral hippocampus, mesencephalic raphe nuclei, and novel localizations in the nucleus of the solitary tract and area postrema. Several sites of expression in the limbic forebrain were found to overlap partially with ones of androgen receptor expression. In pituitary, rat and mouse displayed CRF-R1 mRNA signal continuously over the intermediate lobe and over a subset of cells in the anterior lobe, whereas CRF-R2 transcripts were expressed mainly in the posterior lobe. The distinctive expression pattern of CRF-R2 mRNA identifies additional putative central sites of action for CRF and/or UCN. Constitutive expression of CRF-R2 mRNA in the nucleus of the solitary tract, and stress-inducible expression of CRF-R1 transcripts in the paraventricular nucleus may provide a basis for understanding documented effects of CRF-related peptides at a loci shown previously to lack a capacity for CRF-R expression or CRF binding. Other such "mismatches" remain to be reconciled.

Animals↗
PubMed2000

Hepatitis virus infections in heart transplant recipients: epidemiology, natural history, characteristics, and impact on survival.

BACKGROUND & AIMS: We have observed a high prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in heart transplant recipients (HTRs). The aim of this study was to assess the epidemiology, natural history, and clinical and biological characteristics of viral hepatitis in HTRs. METHODS: From 1983 to 1992, 874 patients underwent heart transplantation at the Pitié-Salpêtrière Hospital, Paris, France, 459 of whom qualified for analysis. A total of 140 patients had posttransplantation hepatitis B, C, or non-A-E. Sixty-nine patients developed HBV infection, 49 HCV infection, 11 HBV-HCV coinfection, and 11 non-A-E hepatitis. RESULTS: HBV was transmitted nosocomially from patient to patient, most likely during endomyocardial biopsies. HCV was mainly transmitted through blood transfusions or the transplanted organ. Clinical and biological findings after 2 years of follow-up showed that 3 patients with an HBV genotype A precore mutant had severe or subfulminant hepatitis and that patients with HBV and HCV infection always progressed to chronicity. In general, patients had mild alanine aminotransferase level increases, a high level of viral replication, and few severe histologic lesions, except for patients infected by precore HBV mutants. Patients coinfected by HBV and HCV tended to have more severe liver lesions. The survival rate 5 years after transplantation in patients with viral hepatitis (HBV, 81%; HCV, 89%; HBV and HCV coinfection, 100%; non-A-E hepatitis, 73%) was similar to that in patients without liver test abnormalities (76%). The actuarial survival curve was also similar in patients with or without liver test abnormalities. CONCLUSIONS: In our experience, histologic liver lesions do not progress rapidly in patients with post-heart transplant infection caused by HBV or HCV. HBV or HCV infection seems to have little impact on the 5-year survival rate of HTRs.

Adolescent↗
PubMed2000

Microbiologic contamination study of nebulizers after aerosol therapy in patients with cystic fibrosis.

BACKGROUND: To evaluate the contamination of delivery systems after an aerosol therapy session in patients with cystic fibrosis who have chronic Pseudomonas aeruginosa infection. METHODS: Fifty-three patients with cystic fibrosis were enrolled in the study from March 1996 to June 1997. All patients were age 7 years or older and had P aeruginosa infection. They also had been treated with recombinant deoxyribonuclease and were capable of producing sputum for culture. RESULTS: Nine devices were excluded for the study. A total of 44 nebulizers were included: 37 from patients with P aeruginosa colonization with a count of 10(6) colony-forming units/mL or more and 7 with a count of between 10(5) colony-forming units/mL and 10(6) colony-forming units/mL. CONCLUSION: This study demonstrates that in the absence of cleaning, nebulizers of patients with cystic fibrosis who are infected with P aeruginosa are likely to be contaminated by a pathogenic flora.

Aerosols↗
PubMed2000

Management of symptomatic and asymptomatic popliteal venous aneurysms: a retrospective analysis of 25 patients and review of the literature.

OBJECTIVE: Popliteal venous aneurysms (PVAs) are an uncommon but potentially life-threatening disease because they can be a source for pulmonary emboli (PE). With the widespread use of venous duplex scanning, PVAs are increasingly found in patients with deep or superficial vein insufficiency, and questions have arisen as to the management of these aneurysms. The purpose of this study was to review our experience in the management of PVAs diagnosed in patients with PE and in patients with chronic venous diseases. METHODS: Twenty-five patients with PVAs were treated in two centers between 1985 and 1999. There were 20 women and five men, with an average age ranging from 33 to 79 years (mean age, 59 years). Twenty-four percent (6/25) presented with PE, and 76% (19/25) of PVAs were discovered during investigation for chronic venous disease (varicosities, n = 13; post-thrombotic symptoms, n = 6). The diagnosis of PVA was achieved in all cases with venous duplex scanning and phlebography. Aneurysms were located in the proximal popliteal vein (n = 17) and at the saphenopopliteal junction (n = 8). Seventy-two percent (18/25) of PVAs were saccular, and 40% (10/25) had an intraluminal thrombus. Two patients with PE underwent cardiac arrest, with one requiring a pulmonary embolectomy. The Fisher exact test showed a statistically significant correlation between PE and the presence of thrombus (50% vs 7% without thrombus, P =.02). Aneurysms were treated with tangential aneurysmectomy and lateral venorrhaphy (n = 19), resection with end-to-end anastomosis (n = 2), resection with interposition of the greater saphenous vein (n = 2) or the superficial femoral vein (n = 1), and resection with vein transposition (n = 1). Two patients who experienced a PE had an inferior vena cava filter placement before surgical repair of the PVA. RESULTS: Mean follow-up was 63 months (range, 11-168 months). No operative deaths occurred, and no patient had evidence of a recurrent PE. Postoperative minor complications (20%) included transient common peroneal nerve palsy (n = 2), postoperative hematoma (n = 2), and wound infection (n = 1). Postoperative thrombosis of the surgical repair occurred in three patients, and patency was restored with anticoagulation therapy. CONCLUSION: Despite its rarity, PVAs should be ruled out with venous duplex scanning in patients with PE and in patients presenting with chronic venous diseases. Because of the unpredictable risk of thromboembolic complications, surgical treatment that is accompanied by a low morbidity rate is indicated in all PVAs. Tangential aneurysmectomy with lateral venorrhaphy is the procedure of choice.

Adult↗
PubMed2000

Associations between drinking water and urinary arsenic levels and skin lesions in Bangladesh.

The present study examined the associations between drinking water and urinary arsenic levels and skin lesions among 167 residents of three contiguous villages in Bangladesh. Thirty-six (21.6%) had skin lesions (melanosis, hyperkeratosis, or both), of which 13 (36.1%) occurred in subjects who were currently drinking water containing concentrations of arsenic < 50 micrograms/L. The risk for skin lesions in relation to the exposure estimates based on urinary arsenic was elevated more than 3-fold, with the odds ratios for the highest versus the lowest quartiles being 3.6 (95% confidence interval, 1.2 to 12.1) for urinary total arsenic and 3.2 (95% confidence interval, 1.1 to 10.0) for urinary creatinine-adjusted total arsenic. The risks for skin lesions in relation to the exposure estimates based on arsenic in drinking water were less strongly elevated, with the odds ratios for the highest versus the lowest quartiles of exposure being 1.7 (95% confidence interval, 0.6 to 5.1) for drinking-water arsenic and 2.3 for cumulative arsenic index. The study suggests that arsenic exposure is associated with skin lesions in the Bangladesh population and that urinary arsenic may be a stronger predictor of skin lesions than arsenic in drinking water in this population.

Adult↗
PubMed2000

Edema and leg volume: methods of assessment.

Various techniques may be used to assess leg edema. The value of these investigations has been discussed in depth in the consensus statement made in Vaux de Cernay in 1997 and supported by Servier Research Group. These techniques can be classified into three groups: The most simple is leg circumference measurement, which can be assessed by a tape measure, or more rigorously with a Leg-O-Meter. This device is a cheap and reproducible method that has been validated and that takes into account the height at which the circumference has been measured. However, circumference measurement is not always correlated with leg (including foot) volume measurement. The second group of techniques assess leg volume. The most simple method is water displacement volumetry, which has been validated in terms of reproducibility. Several other devices have been used: optoelectronic methods, computed tomography, magnetic resonance imaging (high resolution), dual X-ray absorptiometry. These methods are expensive and not all of them have been validated, but these might be the future investigations of choice. Some other investigations assess immediate variations in volume such as water displacement using dynamic foot volumetry, rheoplethysmography, strain gauge plethysmography, and air plethysmography. The assessment made by these methods (using postural, dynamic, or compressive maneuvers) is more an assessment of the venomuscular pump and/or venous outflow than volume assessment. In conclusion, edema, an early and frequent sign of chronic venous insufficiency (CVI), can be precisely measured by several methods. This measurement can be considered one of the most objective ways of assessing treatment efficacy in CVI-associated edema.

Absorptiometry, Photon↗
PubMed2000

Role of duplex imaging in endovenous obliteration for primary venous insufficiency.

PURPOSE: To assess the role of duplex imaging in defining suitable pathological anatomy for endovenous obliteration and characterizing its treatment outcomes over time. METHODS: Eighteen lower limbs in 17 patients (12 women; mean age 48 years; range 29-74 years) presenting with varicose greater saphenous veins (GSVs) were treated with endovenous obliteration without adjunctive high ligation. Duplex imaging was used as an intraprocedural guidance tool for vein access and catheter positioning and for preprocedural evaluation and serial surveillance after the procedures. RESULTS: In the 18 limbs, preprocedural duplex scanning defined reflux owing to incompetence of the terminal valve (n = 6), subterminal valve (n = 9), or truncal valve (n = 3). Duplex imaging facilitated percutaneous vein puncture and was essential in catheter positioning at the saphenofemoral junction (SFJ). At 1 week, the saphenous trunks of all 18 limbs were either shrunken and obliterated (n = 7) or occluded by thrombus without shrinkage (n = 11). By 6 months, 7 GSVs were no longer sonographically visible, 10 were shrunken and obliterated, and 1 had a segmental partial recanalization. In the 15 limbs with terminal or subterminal valve incompetence at 1 week, 5 had total SFJ obliteration, 4 had > or =1 patent tributaries draining directly into the femoral vein through an open SFJ, and 6 had > or =1 patent tributaries draining into an open SFJ through a short (<2 cm) proximal saphenous trunk. By 6 months, only 1 limb had total SFJ occlusion; the other 14 had at least 1 persistent or reopened tributary. CONCLUSIONS: Duplex scanning is indispensable for selecting patients, guiding the procedure, and defining the morphological maturation and hemodynamic changes that appear to characterize successful endovenous obliteration.

Adult↗
PubMed2000

Reconstructive surgery for deep venous reflux: a report on 144 cases.

This retrospective study was conducted on 144 lower extremities (133 patients) with deep venous reflux treated with surgery to restore venous valvular function. Clinically, 51% of patients were in class C5-C6, and based on etiology, patients were equally divided into primary and secondary venous disease. Four surgical procedures were used: valvuloplasty (n=85), transposition (n=18), transplantation (n=32), or Psathakis' technique II (n=9). The procedure chosen was determined mainly by the feasibility of the technique in the above-mentioned preferred order. Thus, 76% of valvuloplasties were performed for primary venous insufficiency. A postoperative venography routinely performed soon after surgery demonstrated a large number of segmental thromboses (20.3%). Their number was statistically different in primary and secondary (PTS) venous disease, respectively 8.8 vs 32.3%. Clinical and hemodynamic results were evaluated (duration of follow-up: 12-168 months) based on etiology and type of procedure. A correlation was established between clinical result (venous ulcer) and efficacy of valvular reconstruction. The latter was satisfactory in valvuloplasties (P=0.005) but not in venous transfer (P=0.35). Overall results were better for primary venous insufficiency than in postthrombotic syndromes (P=0.03).

Adult↗
PubMed1999

Results of valvuloplasty in patients presenting deep venous insufficiency and recurring ulceration.

The purpose of this retrospective study was to assess mid-term results of valvuloplasty in patients presenting chronic recurring venous stasis ulceration. From 1988 to 1993, valvuloplasty was performed in the superficial femoral vein of 33 lower extremities in 28 patients presenting recurring ulceration. In 23 cases, previous surgery in the superficial venous system or perforating vein had failed. Preoperative work-up demonstrated primary deep venous insufficiency (PDVI) in 22 extremities (group I), proximal PDVI in association with distal postthrombotic syndrome (PTS) in 10 (group II), and Klippel-Trenaunay syndrome in 1. Hemodynamic assessment with tourniquet placement demonstrated a mean venous return time of 9 sec (+10, -8). Descending femoral phlebography showed Kistner grade 4 in 30 cases. Outcome was evaluated by clinical examination and Dupplex scan with photophlethysmography at follow-up times ranging from 2 to 7.6 years (mean: 51 months). Correlation between outcome of valvuloplasty and clinical findings was excellent. The incidence of poor clinical and hemodynamic results was higher for patients with PTS. Valve repair in association with surgery for superficial vein insufficiency and ligation of perforators gives good results in patients with isolated PDVI.

Adult↗
PubMed1999

Comparative antimicrobial resistance and genomic diversity of Escherichia coli isolated from urinary tract infections in the community and in hospitals.

Well-defined community- and nosocomially-acquired isolates of Escherichia coli responsible for urinary tract infections were studied for their resistance to beta-lactams, quinolones, and co-trimoxazole, antibiotics widely used for treatment of urinary infections. For each strain, an antibiogram was obtained using the Vitek automat, which estimates the minimal inhibitory concentrations of various drugs. Nosocomial strains were significantly more amoxycillin-resistant than community strains (P = 0.01) and were also significantly more resistant to co-trimoxazole (P = 0.025) and first generation quinolones (P = 0.02) than the latter. To determine whether this was due to transmission of strains within the hospital, DNA restriction patterns, established using XbaI enzyme and separation by pulsed-field gel electrophoresis, were compared. Extreme genomic diversity was found among both the community and nosocomial strains. The increased frequency of resistance among nosocomial strains is thus not due to transmission of resistant hospital strains but probably results from the selection of resistant strains from the endogenous flora of patients.

Anti-Bacterial Agents↗
PubMed1999

Characterisation of dermonecrotic toxin-producing strains of Pasteurella multocida subsp. multocida isolated from man and swine.

Thirty-six isolates, from man or swine, of Pasteurella multocida subsp. multocida producing (n = 13) or not producing (n = 23) the dermonecrotic toxin (DNT) were studied by numerical analysis, capsular typing and ribotyping. Toxigenic strains were also characterised by restriction fragment length polymorphism (RFLP) of the toxA gene and pulsed-field gel electrophoresis (PFGE). Numerical analysis differentiated the Pasteurella species and subspecies, but did not discriminate between toxigenic and nontoxigenic strains. RFLP demonstrated that toxA was located in a conserved part of the chromosome of all toxigenic strains. Ribotyping provided evidence of a close association between DNT production and one of the six EcoRI ribotypes designated as E2. In contrast, PFGE provided evidence for significant DNA polymorphism amongst the toxigenic strains. Results of phenotypic and genotypic studies suggested that toxigenic strains do not form a clone within the subspecies multocida. No difference was found between toxigenic strains of porcine or human origin by biochemical characterisation, capsular serotyping or genomic typing methods.

Animals↗
PubMed1999

Increasing incidence and comparison of nalidixic acid-resistant Salmonella enterica subsp. enterica serotype typhimurium isolates from humans and animals.

We determined the resistance to quinolone of 309 Salmonella enterica subsp. enterica serotype Typhimurium strains isolated from humans and animals (cattle, pigs, or poultry) in 1995 or 1996. Nalidixic acid resistance increased from 8.5% in 1995 to 18.6% in 1996. The highest resistance levels correlated with a mutation at Ser-83 (or Asp-82). All strains remained ciprofloxacin susceptible. Human and animal isolates were compared by pulsed-field gel electrophoresis, and the banding patterns of the human isolates most closely matched those of the bovine isolates.

Animals↗
PubMed1999

[Leg perforating veins].

Our knowledge of the so-called incompetent leg perforating veins remains questionable. Anatomic and hemodynamic studies show that perforators in a healthy subject do not always convey inward flowing blood. Are incompetent perforating veins more frequent with increasing severity of chronic venous disease? Answering this question is difficult as no consensus has been established on how to assess incompetent leg perforating veins and we have no gold standard to refer to. The number of incompetent leg perforating veins is generally greater in severe chronic venous disease although their frequency in clinical stage 4 to 6 (CEAP classification) is not statistically different. This means that incompetent leg perforating veins are not markers of severity of chronic venous insufficiency. When analyzing published series which take into account etiology (primary or secondary venous diseases) the frequency of incompetent perforating veins is variable. Is surgical management required when incompetent leg perforating veins are present? Angiologists and surgeons have not come to an agreement on this point. What can be recommended today? It is generally accepted that the more severe the disease the more worthwhile surgical treatment. Technically speaking, subfascial endoscopic ligature is a promising new method although long-term results are still lacking. We must watch carefully the prospective and randomized studies which have been started in different countries. A lot of questions, only a few reliable answers.

Catheterization↗
PubMed1999

[Fate of the competence of the valvular apparatus of the femoral veins after cryopreservation. Preliminary study].

PURPOSE: The aim of this study was to determine the impact of cryopreservation on the competency of human femoral vein valve. MATERIALS AND METHODS: Nine superficial femoral veins bearing 24 valves were harvested in brain death patients (5 men, mean age 32 years, range 16 to 63 years). Veins were divided in 24 segments bearing only one valve. Each segments was tested for reflux by using a pressure column filled with heparinized saline. After harvest, vein segments were kept in Belzer solution with antibiotics (gentamycin, colistin, lincomycin and amphotericin B). Histological study was undertaken in a fresh valve segment (n = 9). The remaining segments (n = 15) were stored in 15% dimethyl sulfoxide (DMSO) and cryopreserved in liquid nitrogen vapor for 120 days. Afterwards the 15 cryopreserved vein segments were thawed in 37 degrees C water bath and were studied for mechanical and histological changes. RESULTS: All the 24 valve segments initially tested were competent. Off the 15 cryopreserved segments only 4 (26%) were found to be non refluxive after cryopreservation. Histological study performed before cryopreservation showed a normal appearance of the vein wall (n = 9). On the contrary after cryopreservation, microscopic examination showed that in the incompetent veins, the endothelium surface was either absent or poor with a marked decrease in elastic fibres. CONCLUSION: This preliminary study indicates that DMSO cryopreservation must be improved in order to preserve vein valve competency: 26% of the cryopreserved valves remained competent. Histological findings also suggest that elastic fibres play a major role in the failure of the vein competency.

Adolescent↗
PubMed1998

Mutations in NS5A region of hepatitis C virus genome correlate with presence of NS5A antibodies and response to interferon therapy for most common European hepatitis C virus genotypes.

A part of the hepatitis C virus (HCV) nonstructural protein 5A (NS5A) amino acid sequence, designated as an interferon (IFN)-sensitive determining region (ISDR), has been shown to be correlated with a response to IFN in Japanese patients. We have shown previously that the presence of NS5A antibodies (Abs) detected by the INNOLIA test (IL-NS5A Ab) is also correlated with a response to IFN. The aim of this study was to investigate, in a wide range of patients, the possible relationship within the NS5A protein between the sequence of ISDR and that used in the INNOLIA test designated as IL3R. Serum samples from 52 patients infected by HCV genotypes 1, 2, and 3 were analyzed before and after treatment. The patients were classified as nonresponders (NRs), responder-relapsers (RRs), or long-term responders (LTRs). We amplified the NS5A region for 42 patients using polymerase chain reaction (PCR), and these amplicons were sequenced directly. The 10 remaining patients were analyzed using PCR with mutation-specific primers. No correlation was found between the IL3R sequence of the HCV strains and the presence of the IL-NS5A Ab for all genotypes. However, for the subtype 1b, only 2 of 11 NR patients tested had an arginin in position 2218 within the ISDR versus 3 of 3 LTR and 10 of 13 RR patients. All patients with R-2218 had IL-NS5A Ab. For the genotype 1a, 2 of 2 LTR and 1 of 3 RR were mutated in position 2216-2218 in comparison to three NR sequences. For the genotype 3, no mutations were found in the region homologous to 1b-ISDR, but 4 of 5 LTR and RR patients had a mutation T-2161 to A or V versus 0 of 3 NR patients. A close correlation was found between arginin in position 2218 in ISDR, the presence of IL-NS5A Ab, and the response to IFN therapy for genotype 1b, but this association did not predict a long-term response. For genotype 3, a potential ISD mutation could be located at the codon 2161.

Amino Acid Sequence↗