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Biomedical subjects

M Deschamps

Publications and source records attributed to M Deschamps.

At least 19 recordsLinked to original sources
PubMed2006

Genetic control of oil content in oilseed rape (Brassica napus L.).

In oilseed rape (Brassica napus L.) like in most oleaginous crops, seed oil content is the main qualitative determinant that confers its economic value to the harvest. Increasing seed oil content is then still an important objective in oilseed rape breeding. In the objective to get better knowledge on the genetic determinism of seed oil content, a genetic study was undertaken in two genetic backgrounds. Two populations of 445 and a 242 doubled haploids (DH) derived from the crosses "Darmor-bzh" x "Yudal" (DY) and "Rapid" x "NSL96/25" (RNSL), respectively, were genotyped and evaluated for oil content in different trials. QTL mapping in the two populations indicate that additive effects are the main factors contributing to variation in oil content. A total of 14 and 10 genomic regions were involved in seed oil content in DY and RNSL populations, respectively, of which five and two were consistently revealed across the three trials performed for each population. Most of the QTL detected were not colocalised to QTL involved in flowering time. Few epistatic QTL involved regions that carry additive QTL in one or the other population. Only one QTL located on linkage group N3 was potentially common to the two populations. The comparisons of the QTL location in this study and in the literature showed that: (i) some of the QTL were more consistently revealed across different genetic backgrounds. The QTL on N3 was revealed in all the studies and the QTL on N1, N8 and N13 were revealed in three studies out of five, (ii) some of the QTL were specific to one genetic background with potentially some original alleles, (iii) some QTL were located in homeologous regions, and (iv) some of the regions carrying QTL for oil content in oilseed rape and in Arabidopsis could be collinear. These results show the possibility to combine favourable alleles at different QTL to increase seed oil content and to use Arabidopsis genomic data to derive markers for oilseed rape QTL and identify candidate genes, as well as the interest to combine information from different segregating populations in order to build a consolidated map of QTL involved in a specific trait.

Agriculture↗
PubMed2003

Principal surface wave velocities in the point focus acoustic materials signature V(z) of an anisotropic solid.

This paper deals with the point focus beam (PFB) acoustic materials signature V(z) of an anisotropic solid, and in particular how it tends to be dominated by a limited number of principal surface rays. These rays are associated with propagation directions in which the Rayleigh wave (RW), pseudo-surface acoustic wave (PSAW) or a lateral wave slowness has an extremum. The phenomenon is interpreted in terms of the complex azimuthally averaged reflectance function of the surface, and also explained on the basis of a ray model. We illustrate the phenomenon with a number of examples, pertaining to the surfaces of single crystal copper and a carbon-fibre epoxy composite. In the case of copper, which has a much larger acoustic impedance than the water couplant, the oscillations in V(z) are dominated by principal RW and PSAW, whereas for the composite there is no RW or pseudo-SAW to be discerned with acoustic microscopy (AM), and V(z) is dominated by principal lateral waves. The utility of PFB AM in the study of anisotropic solids is further elaborated with examples showing how V(z) is sensitive to surface orientation, and how V(z) is affected by the presence of a surface over layer. The phenomena examined in this paper expand the scope for determining materials characteristics, such as elastic constants, crystallographic orientation, residual stress and over layer properties, from PFB V(z) measurements.

Anisotropy↗
PubMed2002

Inhomogeneous plane wave and the most energetic complex ray.

This paper presents a study on the wave surfaces of anisotropic solids. In addition to the classical and real rays, which are defined by the normal to the slowness surfaces, it is obtained complex rays, which are associated to specific inhomogeneous plane waves. Referring to the complex Christoffel's equation and to the Fermat's principle, an intrinsic equation can be associated to these complex rays. Limiting the study to principal planes and plotting the associated complex wave surfaces, it can be shown that four energetic rays always exist in any directions for both quasi-isotropic and anisotropic media (even beyond the cusp). Consequently, it is always possible to define four closed wave surfaces (real or not).

Journal Article↗
PubMed2002

Meckel's diverticulum and mesenterium commune in a patient with gastrointestinal bleeding.

Lower gastrointestinal bleeding after aspirin intake was reported in a 64-year-old woman. Gastroscopy, colonoscopy and selective mesenteric angiography failed to reveal the source of hemorrhage; only a midgut malrotation was suggested by angiography. Small bowel enema finally demonstrated a blind sac on the antimesenteric border of the ileum, corresponding to a Meckel's diverticulum. This embryological remnant of the vitelline duct was associated with a mesenterium commune. Laparoscopy confirmed the small bowel study, and resection of the diverticulum was easily carried out. It is, to our knowledge, the first time that these developmental abnormalities have been preoperatively diagnosed together.

Aspirin↗
PubMed2001

Monophosphoryl lipid A adjuvant reverses a principal histologic parameter of formalin-inactivated respiratory syncytial virus vaccine-induced disease.

The mechanisms by which administration of a formalin-inactivated respiratory syncytial virus vaccine resulted in enhanced disease among children after they later became naturally infected with the virus remains largely undefined. After immunization and live virus challenge, the cotton rat demonstrated the histopathologic marker of the enhanced disease, polymorphonuclear leukocyte infiltration of lung alveolar spaces. We now report that immunization with formalin-inactivated vaccine formulated with the adjuvant, 3-deacylated monophosphoryl lipid A, dramatically reduces or eliminates the polymorphonuclear leukocyte infiltration within the alveoli of cotton rats post-challenge. We suggest, that this or similar adjuvants may be beneficial components of candidate non-replicating respiratory syncytial virus vaccines, whose development has been hampered by safety concerns.

Adjuvants, Immunologic↗
PubMed2001

Probing aerogels by multiple quantum filtered (131)Xe NMR spectroscopy.

At the interface between solid surfaces and cavities filled with gaseous or liquid xenon, the nuclear magnetization of (131)Xe (S = (3)/(2)) is subject to quadrupolar interactions which may lead to higher rank single-quantum coherences that can be described by tensor elements T(2,)(+/-)(1) and T(3,)(+/-)(1). This can be demonstrated by multiple-quantum filtered (MQF) NMR experiments. In gaseous xenon on Pyrex surfaces, the primary source of such coherences was shown to be coherent evolution induced by a nonvanishing average quadrupolar coupling. In this contribution, MQF NMR is applied to aerogels filled with liquid xenon to demonstrate the potential of this technique for material sciences. Xenon in the liquid phase provides a sufficient spin density to obtain reasonable signal-to-noise ratios. Coherent evolution and relaxation both contribute to the creation of higher rank coherences depending on the presence or absence of water molecules on the surface. These two processes can be distinguished experimentally and provide complementary information about the surface of the host material.

Journal Article↗
PubMed2000

Surface acoustic waves at the vacuum-thermoviscoelastic solid interface.

The present investigation concerns the propagation of surface waves at the vacuum-solid interface of a solid which is isotropic and thermoviscoelastic, i.e., for which the effects of heat conductivity need to be taken into account. Calculations show that, in addition to the Rayleigh wave, a thermal surface wave propagates that couples both the thermal and the elasticity effects. This latter wave is interpreted in terms of evanescent plane waves. The displacement field associated with this wave is calculated and interpreted. Some experimental results are also presented.

Acoustics↗
PubMed2000

Ultrasonic waves propagation in absorbing thin plates application to paper characterization.

Guided wave theory is applied to a thin orthotropic and absorbing plate for low frequency propagation of ultrasonic waves. The aim of this paper is to give some physical interpretations of the non-destructive characterization of paper materials, which are cellulosic fibrous networks. It is shown that the propagation problem reduces to two normal modes of propagation in the plane of the plate. Each of them depends on four complex and independent stiffnesses that are combinations of elementary complex stiffnesses of the media. The imaginary part of these stiffnesses corresponds to a possible mechanism of energy dissipation during the wave propagation for this kind of material. The reverse problem, which gives four complex values, is then numerically solved using a small attenuation assumption. The specially designed experimental set-up has led to the first measurements of tracing paper damping factors. The phase velocity measurements of the plate waves agree with the results already found by several paper researchers. As a particular and new result, the shear wave velocities are found to present a quasi-isotropic repartition in the plane of the paper sheet. It was found that the absorbing phenomenon can occur for each propagation mode in such a material. The attenuation values are small, except for one of them that corresponds to a coupling term in the propagation model. The anisotropy of their repartition is also shown in the case of quasi-longitudinal waves.

Cellulose↗
PubMed2000

Identification of occupational cancer risks in British Columbia. A population-based case-control study of 995 incident breast cancer cases by menopausal status, controlling for confounding factors.

Lifetime occupational histories as well as information on known and suspected breast cancer risk factors were collected by means of a self-administered questionnaire from 1018 women with incident breast cancer ascertained from the British Columbia Cancer Registry, and from 1020 population controls. A matched case-control study design was used. Conditional logistic regression for matched sets data and the likelihood ratio were used in a two-step procedure and were performed separately for pre-menopausal women, post-menopausal women, and for all cases combined. Excess risk was noted for several white-collar occupations. Significantly increased risk was observed: (1) among pre-menopausal women: in electronic data-processing operators; barbers and hairdressers; in sales and material processing occupations; and in the food, clothing, chemical and transportation industries; (2) among post-menopausal women: in schoolteaching; in medicine, health, and nursing occupations; in laundry and dry-cleaning occupations; and in the aircraft and automotive, including gasoline service station, industries. Several significant associations were also seen in the combined group of pre- and post-menopausal women, particularly in crop farmers and in the fruit and vegetable, publishing and printing, and motor vehicle repair industries. The results of this study suggest excess breast cancer risk in a number of occupations and industries, notably those that entail exposure to solvents and pesticides.

Adolescent↗
PubMed2000

Comparison between the dispersion curves calculated in complex frequency and the minima of the reflection coefficients for an embedded layer

Analytical solutions of Lamb functions for symmetric and antisymmetric elastodynamic modes propagating within a solid layer embedded in an infinite medium are presented. Alternative theoretical analyses of such modes are performed, first in terms of the usual approach of harmonic heterogeneous plane waves (real frequency and complex slowness) and then in terms of transient homogeneous plane waves (complex frequency and real slowness). An example structure of a 0.1-mm-thick "alpha case" (an oxygen-rich phase of titanium that is relatively stiff) plate embedded in titanium is used for the study. A large difference between the usual dispersion curves calculated in real frequency and complex slowness and those calculated in complex frequency and real slowness is shown. Thus the choice between a spatial and a temporal parameter to describe the imaginary part of the guided waves is shown to be significant. The minima and the zeros of the longitudinal and shear plane-wave reflection coefficients are calculated and are compared with the dispersion curves. It is found that they do not match with the dispersion curves for complex slowness, but they do agree quite well with the dispersion curves for complex frequency. This implies that the complex frequency approach is better suited for the comparison of the modal properties with near-field reflection measurements.

Journal Article↗
PubMed2000

Transient Lamb waves: comparison between theory and experiment

This paper presents an experimental investigation of the generation of transient Lamb waves inside an immersed plate by a time limited signal. The transient Lamb waves are the solutions of the characteristic equation of the plate for complex frequency and real slowness, in contrast to the leaky Lamb waves, for which the slowness is complex and the frequency is real. By using a large transducer in agreement with the real slowness assumption, the excitation of these transient Lamb waves is observed experimentally both in reflection and transmission for a tone burst excitation. Particular attention is paid to the A0 mode for which the amplitude increases exponentially in time. As a result, the total reflected waveform contains in this case a transient contribution, coming from the generation of the A0 mode, that precedes the forced regime. It is shown that there is a very good agreement between the theoretical and the experimental time exponential amplitude variations of the transient Lamb waves. For the A0 mode, the transient signal is qualitatively explained by a group velocity higher than the phase velocity.

Journal Article↗
PubMed2000

Efficacy and safety studies of a recombinant chimeric respiratory syncytial virus FG glycoprotein vaccine in cotton rats.

Several formulations of a recombinant chimeric respiratory syncytial virus (RSV) vaccine consisting of the extramembrane domains of the F and G glycoproteins (FG) were tested in cotton rats to evaluate efficacy and safety. The FG vaccine was highly immunogenic, providing nearly complete resistance to pulmonary infection at doses as low as 25 ng in spite of inducing relatively low levels of serum neutralizing antibody at low vaccine doses. Upon RSV challenge animals primed with FG vaccine showed quite mild alveolitis and interstitial pneumonitis, which were eliminated by the addition of monophosphoryl lipid A to the formulation.

Animals↗
PubMed1998

A clinically relevant HIV-1 subunit vaccine protects rhesus macaques from in vivo passaged simian-human immunodeficiency virus infection.

OBJECTIVES: To investigate whether immunization with recombinant HIV-1 envelope protein derived from a clinical isolate could protect macaques from infection with an in vivo passaged chimeric simian-human immunodeficiency virus (SHIV). DESIGN AND METHODS: A total of 16 animals were studied from which three groups of four animals were immunized with vaccine formulations of the CC-chemokine receptor-5-binding recombinant gp120 of HIV-1W6.1D. Four weeks after the last immunization, all 16 animals were intravenously challenged with in vivo passaged SHIV derived from the same HIV-1 group B clinical isolate (W6.1D) as the vaccines. RESULTS: Vaccine protection from infection was demonstrated in 10 out of 12 macaques immunized with recombinant gp120. Complete protection from infection was achieved with all of the animals that received the SBAS2-W6.1D formulation, a potent inducer of both T-cell and humoral immune responses. Partial protection was achieved with SBAS1-W6.1D, a formulation based on immunomodulators known to induce T-cell responses in humans. In vaccinated animals that were infected, virus load was reduced and infection was delayed. CONCLUSIONS: In a relatively large number of primates, vaccine efficacy was demonstrated with a clinically relevant HIV-1 vaccine. These results reveal that it is possible to induce sterilizing immunity sufficient to protect from infection with SHIV which was passaged multiple times in vivo. Our findings have implications for current HIV-1 clinical vaccine trials and ongoing efforts to develop safe prophylactic AIDS vaccines.

AIDS Vaccines↗
PubMed1998

Reducing cervical cancer among First Nations women.

First Nations women in British Columbia have a four to six times higher mortality rate from cancer of the cervix than do women in the general population. Their participation in the provincial Cervical Cytology Screening Program (CCSP) is less regular and less frequent than other women in B.C. Likewise, they have more difficulty in obtaining culturally suitable health care services from respectful and consistent professionals. These issues should be of critical concern to nurses, as nurses provide the majority of health services to First Nations people.

British Columbia↗
PubMed1998

Long term disability rates in a cohort of Air Canada pilots.

Causes of long term disability (LTD) were collected between January 1, 1981 and December 31, 1990 among all active pilots in a cohort of Air Canada pilots. During this 10-yr period, 474 (20.9%) of the 2271 pilots had LTD; there were 1107 cases of LTD corresponding to a total duration of leave of absence of 4161 mo. Frequencies of the main diagnostic categories were: injuries: 249 (22.5%); mental disorders: 175 (15.8%); circulatory system: 157 (14.2%); digestive system: 128 (11.6%); and musculoskeletal system: 121 (10.9%). LTD rates increased with age, ranging from 1.86-9.22 per 1000 pilots per year from the younger (20-29 yr) to the older age group (50-59 yr), respectively. Several causes of LTD could be potentially preventable, in particular injuries which accounted for 63.6% of all causes in the younger age group and remained a significant condition at subsequent ages.

Absenteeism↗
PubMed1996

Cohort study of Air Canada pilots: mortality, cancer incidence, and leukemia risk.

Despite the special working environment and exposures of airline pilots, data on risk of death and cancer incidence in this occupational group are limited. The authors investigated a cohort of 2,740 Air Canada pilots who contributed 62,449 person-years of observation. All male pilots employed for at least 1 year on and since January 1, 1950, were studied. The cutoff date for outcome information was December 31, 1992. Standardized mortality ratio (SMR) and standardized incidence ratio (SIR) were used to compare mortality rates and cancer incidence rates of the cohort with the respective Canadian population rates. Ninety percent confidence intervals of the SMR and SIR were calculated. Statistically significant decreased mortality was observed for all causes (SMR = 0.63, 90% confidence interval (CI) 0.56-0.70), for all cancers (SMR = 0.61, 90% CI 0.48-0.76), and for all noncancer diseases (SMR = 0.53, 90% CI 0.45-0.62). Mortality from aircraft accidents was significantly raised (SMR = 26.57, 90% CI 19.3-35.9). Significantly decreased cancer incidence was observed for all cancers (SIR = 0.71, 90% CI 0.61-0.82), rectal cancer (SIR = 0.42, 90% CI 0.14-0.96), lung cancer (SIR = 0.28, 90% CI 0.16-0.46), and bladder cancer (SIR = 0.36, 90% CI 0.12-0.82). Prostate cancer (SIR = 1.87, 90% CI 1.38-2.49) and acute myeloid leukemia (SIR = 4.72, 90% CI 2.05-9.31) were significantly increased. The preferred relative risk model for radiation-induced nonchronic lymphoid leukemia (Beir V report) was applied to the cohort by using published estimates of in-flight radiation exposures. The estimated relative risk ranged from 1.001 to 1.06 and did not differ significantly from the observed SIR (SIR = 1.88, 90% CI 0.80-3.53). However, the incidence rate of acute myeloid leukemia was significantly increased. Monitoring of in-flight radiation exposure and long-term follow-up of civil aviation crew members is needed to further assess cancer incidence and leukemia risk in this special occupational group.

Accidents, Aviation↗
PubMed1996

[Treatment with silicone oil in complicated retinal detachment. Anatomopathological test of 2 enucleated eyes].

Two eyes with a complicated retinal detachment were operated using intraocular silicone oil injection. They were enucleated 33 and 12 months after the operation because of painful secondary glaucoma and corneal dystrophy. Using light and electron microscopy, silicone oil vacuoles were observed in the corneal depth, the iris stroma, the trabecular meshwork and in lens remnants. There was an angle closure due to iridocorneal synechia. The same vacuoles were recognized in epiretinal membranes, in the internal and external layers of the retina and in the pigment epithelium. When the retina was detached, silicone oil vacuoles were present in the choroidal vessels.

Aged↗