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Biomedical subjects

L Legrand

Publications and source records attributed to L Legrand.

At least 19 recordsLinked to original sources
PubMed2006

[Mycoplasma pneumoniae infections: retrospective study in Basse-Normandie, 1997-2005. Epidemiology--diagnostic utility of serology and PCR for a rapid diagnostic].

OBJECTIVES: The objective of this study was to evaluate the epidemiology of Mycoplasma pneumoniae (Mpn) infections in Basse-Normandie by a retrospective analysis of serological and PCR data, and to confirm the diagnostic utility of PCR and serology. METHODS: From 1997 to August 2005, 6156 serum samples and 6123 respiratory tract samples were collected from hospitalised patients and evaluated for the diagnosis of Mpn infection by PCR, serological assays, or by the two tests. During the epidemic period (2004-2005), the results of 1489 patients were analysed. RESULTS: Over the 9-y period, the seroprevalence was 40,4% and we reported on 525 cases with serologically or/and PCR proven Mpn infection, according a cyclic pattern spaced out 7 years. During the epidemic period, the seroprevalence increased to 50,2% and the rate of infections was 8.3%. The analysis of the 124 cases of Mpn infection showed typical epidemiological characteristics: a peak of incidence among the children and young adults, a summer-winter pattern and some coinfections with viral strains. For diagnosis of Mpn infection, the comparison of PCR and serological assays among 36 patients showed a concordance of only 41.7%. CONCLUSION: Mpn infections were endemic and outbreaks were observed according cyclic pattern with a high incidence specially in the children. Sensitive and specific tests were now available for early and reliable diagnosis. In children, the combination of the PCR on nasopharyngeal samples and the IgM EIA serology test were recommended. In adults, the PCR was privilegiated.

France↗
PubMed2006

Characteristics of tracheostomy phonation valves.

Phonation valves are commonly used devices that allow the restoration of speech in tracheostomised patients. However, their use should not compromise the physiological benefit of tracheostomy. Six commercialised phonation valves were studied in a dynamic set-up simulating a respiratory frequency of 20 breaths.min(-1), a tidal volume of 0.5 L and a peak flow rate of 0.5 L.s(-1). Resistance and additional work of breathing (WOB) were calculated. In 10 tracheostomised patients, evaluations using no phonation valve (baseline), and the most and one of the least resistive valves were carried out. Respiratory patterns and gas exchanges were recorded. Inspiratory difficulty was evaluated using the modified Borg scale. Valves displayed a wide array of resistance ranging 1.3-5.9 cmH2O.L(-1).s(-1). Additional WOB varied with a ratio of 4.4 between the best and the worst valve. While the different clinical conditions did not modify respiratory patterns and gas exchanges, a significant effect on the Borg scale rating was observed using ANOVA and post hoc analysis of baseline versus worst valve and one of the best valves versus worst valve. In conclusion, the variety of aerodynamic characteristics of phonation valves should be considered when choosing the device, according to the underlying condition of the patients benefiting from their use.

Adult↗
PubMed2005

Development of three multiplex RT-PCR assays for the detection of 12 respiratory RNA viruses.

Three multiplex hemi-nested RT-PCR assays were developed to detect simultaneously 12 RNA respiratory viruses: influenza viruses A, B and C, human respiratory syncytial virus (hRSV), human metapneumovirus (hMPV), parainfluenza virus types 1-4 (PIV-1, -2, -3 and -4), human coronavirus OC43 and 229E (HCoV) and rhinovirus (hRV). An internal amplification control was included in one of the RT-PCR assays. The RT-PCR multiplex 1 and the hemi-nested multiplex 1 detected 1 and 0.1 TCID50 of RSV A, respectively, and 0.01 and 0.001 TCID50 of influenza virus A/H3N2, respectively. Two hundred and three nasal aspirates from hospitalised children were retrospectively tested in comparison with two conventional methods: direct immunofluorescence assay and viral isolation technique. Almost all samples (89/91) that were positive by immunofluorescence assay and/or viral isolation technique were detected by the multiplex assay. This method also detected an additional 85 viruses and 33 co-infections. The overall sensitivity (98%), rapidity and enhanced efficiency of these multiplex hemi-nested RT-PCR assays suggest that they would be a significant improvement over conventional methods for the detection of a broad spectrum of respiratory viruses.

Child↗
PubMed2004

[Acute respiratory tract infections due to a human metapneumovirus in children: descriptive study and comparison with respiratory syncytial virus infections].

BACKGROUND: A new paramyxovirus, the human metapneumovirus was recently isolated. We report the first French cases collected between 2000 and 2002. MATERIAL AND METHODS: Samples were obtained from nasopharyngeal aspirates from children hospitalised for acute respiratory tract infection in hospitals of Caen and Flers in Basse-Normandie. Human metapneumovirus was studied by polymerase chain reaction on negative samples for respiratory syncytial virus, influenza A and B virus, parainfluenza (1, 2 and 3) virus, adenovirus, coronavirus and rhinovirus. Comparison between metapneumovirus virus and respiratory syncytial virus infections was done after matching sex, age and infection month. RESULTS: Twenty-six human metapneumovirus infections were identified. A comparative study of a matched group of children infected by respiratory syncytial virus found no significative difference for hospitalisation motive, clinical criteria and treatment. CONCLUSION: The human metapneumovirus is responsible for typical acute bronchiolitis in children.

Acute Disease↗
PubMed2004

Left ventricular ejection fraction calculation from automatically selected and processed diastolic and systolic frames in short-axis cine-MRI.

The calculation of the left ventricular ejection fraction (LVEF) is dependent upon the accurate measurement of diastolic and systolic left ventricular volumes. Although breath-hold cine magnetic resonance imaging (MRI) allows coverage of the whole cardiac cycle with an excellent time resolution, many authors rely on the visual selection of diastolic and the systolic short-axis slices in order to reduce the postprocessing time. An automatic method was developed to detect the endocardial contour on each image, allowing an automatic selection of the systolic frame. The calculated ejection fraction was compared with radionuclide ventriculography (RNV). Sixty-five patients were examined using an electrocardiogram (ECG)-gated gradient echo sequence. Among these examinations, manual and automatic processing with MRI were compared when the time of the systolic frame concorded. Good correlations have been found between the automatic MRI approach and RNV, and between manual and automatic processing on MRI alone. The results show that the automatic determination of the ejection fraction is feasible, and should constitute an important step toward a larger acceptance of MRI as a routine tool in heart disease imaging. One major benefit of using automatic postprocessing is that it may eliminate the visual choice of the systolic frame, inaccurate in more than 50% of the studied patients.

Adult↗
PubMed2002

Two polymorphs of lysozyme nitrate: temperature dependence of their solubility.

Two crystallographic forms of lysozyme nitrate are known, namely monoclinic and triclinic. Having previously determined the temperature dependence of the solubility of the monoclinic form (0.2 M NaNO (3) solutions at pH = 4.5) [Legrand et al. (2001). J. Crystal Growth 232, 244-249], we focus here on the solubility of the triclinic form. The temperature dependence of the solubility of this crystallographic form has been measured with a static light device developed in our laboratory. This device allows to observe of the dissolution of one phase and/or the occurrence of a new one by varying the temperature with a sweep rate as low as 0.6 degree/hour. The new solubility data are complemented with crystallographic data of the triclinic form for the sake of completeness. The faces of a triclinic crystal are indexed. The crystallisation enthalpy of the triclinic form is deduced from these new results. These new solubility data allow us now to discuss (1). the published protocols used to obtain the monoclinic and triclinic forms of lysozyme nitrate and (2). the phase transformation.

Animals↗
PubMed2001

A 3-D marker-free system for the analysis of movement disabilities--an application to the legs.

The aim of this paper is to describe an approach allowing the analysis of human motion in three-dimensional (3-D) space. The system that we developed is composed of three charge-coupled-device cameras that capture synchronized image sequences of a human body in motion without the use of markers. Characteristic points belonging to the boundaries of the body in motion are first extracted from the initial images. Two-dimensional superquadrics are then adjusted on these points by a fuzzy clustering process. After that, the position of a 3-D model based on a set of articulated superquadrics, each of them describing a part of the human body, is reconstructed. An optical flow process allows the prediction of the position of the model from its position at the previous time, and gives initial values for the fuzzy classification. The results that we present concern more specifically the analysis of movement disabilities of a human leg during gait. They are improved by using articulation-based constraints. The methodology can be used in human motion analysis for clinical applications.

Persons with Disabilities↗
PubMed1999

Automatic detection of left ventricular contours from cardiac cine magnetic resonance imaging using fuzzy logic.

RATIONALE AND OBJECTIVES: Gated cardiac cine magnetic resonance imaging provides accurate dynamic data of the left ventricular function. However, the manual extraction of important physiologic parameters such as myocardium wall thickness and left ventricular volumes is invariably time consuming and subjective. To reduce the variability and time constraints inherent in observer contour tracing, the authors developed an automatic left ventricle contour-detection method. METHODS: The purpose was to apply fuzzy logic-based automatic contour detection to identification of endocardial and epicardial borders in short-axis magnetic resonance images. The automatic contouring was compared with manual tracing using the calculated ejection fraction as the comparison criterion. RESULTS: A good correlation was found between the two approaches (r2 = 0.98). CONCLUSIONS: The ejection fraction can be obtained using this automatic contouring method.

Adult↗
PubMed1998

A marker-free system for the analysis of movement disabilities.

A major step toward improving the treatments of disabled persons may be achieved by using motion analysis equipment. We are developing such a system. It allows the analysis of plane human motion (e.g. gait) without using the tracking of markers. The system is composed of one fixed camera which acquires an image sequence of a human in motion. Then the treatment is divided into two steps: first, a large number of pixels belonging to the boundaries of the human body are extracted at each acquisition time. Secondly, a two-dimensional model of the human body, based on tapered superquadrics, is successively matched with the sets of pixels previously extracted; a specific fuzzy clustering process is used for this purpose. Moreover, an optical flow procedure gives a prediction of the model location at each acquisition time from its location at the previous time. Finally we present some results of this process applied to a leg in motion.

Biomechanical Phenomena↗
PubMed1997

Automatic detection of cardiac contours on MR images using fuzzy logic and dynamic programming.

This paper deals with the use of fuzzy logic and dynamic programming in the detection of cardiac contours in MR Images. The definition of two parameters for each pixel allows the construction of the fuzzy set of the cardiac contour points. The first parameter takes into account the grey level, and the second the presence of an edge. A corresponding fuzzy matrix is derived from the initial image. Finally, a dynamic programming with graph searching is performed on this fuzzy matrix. The method has been tested on several MR images and the results of the contouring were validated by an expert in the domain. This preliminary work clearly demonstrates the interest of this method, although a formal evaluation has to be done.

Fuzzy Logic↗
PubMed1989

Percutaneous transluminal angioplasty without anticoagulation.

This paper presents the results of a retrospective study of 110 percutaneous transluminal angioplasties done over a period of two years on 110 consecutive patients. Anticoagulation or antiplatelet drugs were not used during or after percutaneous transluminal angioplasty. Life-table analysis was used to calculate success rates at one and three months following the procedure. Success rates were determined using three criteria: clinical improvement, pre- and post-percutaneous transluminal angioplasty Doppler studies, and radiographic appearance. Claudication was present in 87 (79%) patients and severe ischemia in 23 (21%) patients. Sixty-eight (62%) PCTAs were done in the iliac arteries, 35 (32%) in the femoral arteries, and 7 (6%) in the popliteal artery. The majority of patients (61%) had 50%-75% arterial stenosis and only 18% had complete occlusion. Percutaneous transluminal angioplasty in the iliac arteries had the best results with cumulative success rates of 90% and 85% at one and three months, respectively. Success rates in the femoral arteries were 83% and 79% and in the popliteal artery 71% and 57% at one and three months, respectively. None of our patients required amputation. Ten patients (9.1%) suffered the following complications within 30 days of percutaneous transluminal angioplasty: death (2), thrombosis (2), perforation (3), minor hematoma (2), and false aneurysm (1). In conclusion, we have shown that percutaneous transluminal angioplasty can be performed safely and effectively without the use of anticoagulation and its associated risks.

Adult↗
PubMed1987

HLA haplotypes in non-familial rheumatoid arthritis.

The frequencies of HLA-A, B, C, DR, and BF haplotypes in 44 unrelated Caucasian patients with definite seropositive rheumatoid arthritis (RA) were compared with haplotype frequencies in controls. Overall, the patients had an increased risk for HLA-DR4, DR3, and DR2 antigens, but frequencies of certain DR4 or DR3 haplotypes were not increased, suggesting the importance of other HLA loci for the evaluation of risk. The presence of DR4 alone was not found to produce an increased risk for RA since the frequencies of certain DR4 haplotypes were similar in patients and controls. Increased frequencies of HLA-B18, DR4, HLA-B15, DR4, and HLA-A1, B8, Cw7, DR3 haplotypes were found in patients. RA susceptibility has been found to be associated with the last two haplotypes in some studies of multiple case families, suggesting that similar genetic mechanisms may underlie the disease in familial and sporadic forms.

Arthritis, Rheumatoid↗
PubMed1986

Combined influences of Gm and HLA phenotypes upon multiple sclerosis susceptibility and severity.

In some Caucasian populations, multiple sclerosis (MS) susceptibility has been independently related to given alleles of HLA or Gm systems that respectively code for major histocompatibility complex class I and II antigens or immunoglobulin G heavy chains. Whether given combinations of alleles at both series of loci simultaneously influence MS susceptibility and/or severity was investigated by comparing 147 French MS patients and 226 geographically-matched healthy controls. The G2m(-23)/HLA-B35 phenotype and G1m(-1)/HLA-B7(-)/HLA-DR2 phenotype were respectively associated with significant protection against (relative risk = 0.05) and susceptibility to (relative risk = 4.3) MS. When considering MS severity, the presence of HLA-B7 antigen correlated with a more severe disease in Gm1/Gm3 heterozygous patients, but not in Gm3/Gm3 homozygous patients. Conversely, an HLA-B12-associated milder disease was restricted to Gm3/Gm3 homozygotes. These results demonstrate the combined influence on MS of genetic loci that are unlinked but immune response-associated. Combined Gm and HLA typing is very likely able to serve as a prognostic indicator in this disease.

Disease Susceptibility↗
PubMed1985

HLA antigens and seronegative rheumatoid arthritis.

HLA antigens and clinical features in a series of 46 Caucasian patients (40 females, 6 males) and definite repeatedly seronegative rheumatoid arthritis (RA) of more than two years' duration (mean 11.6 years) were compared with those in 77 seropositive RA patients and 110 controls of the same ethnic and geographic origin. Seronegative RA appeared to be less often erosive than seropositive RA, and seronegative patients had fewer extra-articular features. The frequency of the HLA antigen DR1 was raised in seronegative patients as compared with controls (p = 0.006, relative risk = 3) and with seropositive patients (p less than 0.05). HLA-DR4 was slightly increased in seronegative patients compared with controls (p less than 0.05) but was clearly less so than in seropositive patients (p less than 0.005). Early onset of disease was very significantly associated with HLA-DR1 in seronegative patients (p = 0.007), whereas HLA-DR4 was present more frequently in seropositive patients with onset prior to age 35 (p less than 0.05). No correlation between HLA antigens and intolerance to drugs was found in seronegative patients, whereas in seropositive patients side effects to gold salts were associated with DR3. These results suggest that seropositive and seronegative RA have distinct HLA-DR associations, especially in disease of early onset, in addition to well established clinical differences.

Adolescent↗
PubMed1985

Delay in diagnosing gastrointestinal injury after blunt abdominal trauma in children.

Intestinal perforation after blunt abdominal trauma in children is rare and thus the diagnosis may be delayed. For this reason the authors reviewed their experience with 12 children to recommend a protocol for investigation that would reduce the delay in diagnosis. Of the 12 perforations, 2 were gastric, 2 duodenal, 7 jejunal and 1 colonic. The diagnosis of jejunal perforation, in particular, was usually delayed because free air was not seen radiologically in the first few hours after injury. This may be because of delayed rupture or spasm of the injured intestine. Serial films were valuable in aiding the diagnosis and are recommended, together with assessment of solid organ injury by radionuclide scanning. In this series peritoneal lavage was not used. No child died.

Abdominal Injuries↗
PubMed1984

HLA-DR genotype risks in seropositive rheumatoid arthritis.

We studied the distribution of HLA-A, B, C, and -DR antigens in 77 Caucasian patients with sero-positive rheumatoid arthritis. Forty-four patients were genotyped and compared with the control panel of 110 unrelated Caucasian genotyped donors. The data obtained confirm the association of DR4 with RA, and reveal an increased risk of disease for patients carrying DR1, DR2, and DR3, compared to the risk for those carrying other antigens, such as DR5, DRw6, and DR7. There is a higher risk for DR4/4 homozygotes than for DR4/1, DR4/2, or DR4/3 heterozygotes. DR4/5, DR4/6, and DR4/7 have a lower risk than the previously mentioned genotypes. The genotype risks are compatible with the inheritance of a single, linked genetic determinant of disease susceptibility, but we are unable to distinguish between recessive and dominant inheritance of susceptibility using the "antigen-frequencies-amongst-diseases" method. DR4 seems to be more frequent in patients in whom onset occurs before the age of 35 (79% vs. 54% DR4 positive). A significant excess of DR3 + is observed in patients with toxic complications following treatment with gold salts (X2(1) = 8.96).

Adult↗
PubMed1982

HLA-and Gm-linked genes affecting the degradation rate of antigens (sheep red blood cells) endocytized by macrophages.

Phagocytosis and catabolism of sheep red blood cells by human peripheral blood phagocytes were studied in 100 normal caucasoid subjects (44 males and 56 females). Both phenomena are highly reproducible, and their indices seem to be biological constants. There is no correlation between these two indices and the indices do not have a correlation with ABO or Rh markers. Further, the phagocytic index has no correlation with HLA and GM markers. However, a low speed of degradation is significantly correlated (p = 0.001) with the HLA-DR3 antigen, and most of the low degraders are significantly correlated (p = 0.006) with both DR3 and Gm 3,23,11 (probably Gm homozygous). Thus the gradient of antigen degradation could be related to an interaction between MHC and Gm immunoglobulin genes, as is found in the mouse [Biozzi's high (H) and low (L) responder strains.

Adult↗