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Biomedical subjects

M Millet

Publications and source records attributed to M Millet.

At least 19 recordsLinked to original sources
PubMed2001

Modification of the rat aortic wall during ageing; possible relation with decrease of peptidergic innervation.

Structural changes of the male rat aorta were followed from birth to old age in male and female rats. In males, the vessel media width and area progressively increase concomitantly with a decrease of nuclei density during ageing, suggesting an hypertrophy of the smooth muscle cells. These correlations were however not evidenced in females. TUNEL-positive cells were found in media of 4 and 6 months in both sexes, mainly on the luminal side and in the adventitia. When biochemical markers were investigated with immunohistochemistry, media was uniformly stained by the anti-vimentin and anti-alpha-smooth actin at all stages investigated. On the contrary, the surface of media stained with anti-desmin decreased during ageing, especially on the luminal side. As observed with electron microscopy, with ageing the endothelium is replaced by small cells with pseudopodia adhering to the vestigial elastic lamina and infiltrating into the extracellular matrix left after the disappearance of smooth muscle cells. In addition, in the older rats (25-29 months) the elastic laminae are completely disorganised. Hypertrophy of the smooth muscle cells was confirmed by this approach. In parallel to this study, perivascular peptidergic innervation was stained with antibodies against calcitonin gene-related peptide (CGRP), substance P (SP), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) at different ages during the whole life of rats. These peptides are present in stages younger than 6 months, then gradually disappear. In one year animals and older, the peptidergic innervation has totally disappeared. We discuss the possible role of peptidergic innervation in the control of the vessel wall cellular stability during ageing.

Actins↗
PubMed2000

Comparison of atmospheric pesticide concentrations measured at three sampling sites: local, regional and long-range transport.

We present the comparison of atmospheric concentrations of eleven currently used pesticides (HCB, alpha-HCH, gamma-HCH, trifluraline, mecoprop, phosalone, atrazine, carbofuran, carbaryl, diuron and isoproturon) measured in remote (Aubure), rural (Colmar) and urban (Strasbourg) areas of Alsace and Vosges regions (cast France). Pesticides samples were collected simultaneously on two of the three sites during the summer season of 1993 and 1994, using a Hi-Vol sampler with Whatman filter paper and XAD-2 resin. The particle and gas phases were collected separately during 24 h. The relative importance of local emissions and local, regional and long distance transport on the contamination of the atmosphere in the three environments (remote, rural and urban) were investigated. To facilitate the interpretation of the results, the alpha/gamma-HCH ratio was used as a tracer of pesticide emissions.

Air Movements↗
PubMed2000

Adsorption/thermal desorption-GC/MS for the analysis of pesticides in the atmosphere.

An analytical methodology using Automatic Thermal Desorption (ATD) and GC/MS was developed for the determination of the pesticides alachlor, atrazine, captan, formothion, lindane and phosalone in atmospheric samples. This methodology was developed to evaluate the atmospheric contamination by pesticides during treatments and by post-application. Atmospheric samples were collected by using (4 i.d. x 89 mm) stainless steel sampling tubes containing 125 mg of adsorbents at a flow rate of 80 ml min-1. Different types of adsorbents were tested for their ability to efficiently trap pesticides under study: Tenax TA, Carbopack Y, Carbopack B, Carbotrap, Carboxen, Chromosorb 106 and XAD-4. Results of experiment show that Tenax gives the better results for all the pesticides used but the use of the thermal-desorption method, especially for pesticides with low volatility and/or poor thermal stability presents some difficulties. This method was validated by the analysis of the contamination of atmosphere, through volatilization by post-application processes, of atrazine in a parcel of 1 ha.

Acetamides↗
PubMed1998

OH radical reactivity of pesticides adsorbed on aerosol materials: first results of experiments with filter samples.

Preliminary results of a new method to investigate the OH radical reactivity of semi-volatile organic compounds (e.g., pesticides) are presented. Terbuthylazine, simazine, sodium benzoate, and bromoxynil were adsorbed on highly disperse silicon dioxide powder as an unreactive carrier at a thickness well below one monolayer. The coated material was suspended in air as an aerosol, sampled on filters, and exposed in an 840-liter Duran chamber to OH radicals, produced by photolysis of hydrogen peroxide in the gas phase. Sunlamps on top of the chamber were used as cold light sources [T(aerosol) approximately 25 degreesC]. OH radical concentrations (10(5)<cOH (cm-3)<3x10(6)) were monitored in the gas phase using a set of four hydrocarbons with well-known OH reactivities as reference compounds. The triazine terbuthylazine (kOH=1.1x10(-11) cm3 s-1) was used as a reference compound in the filter samples. Simazine and isoproturon were found to react with a comparable OH rate constant with respect to terbuthylazine. Sodium benzoate reacts about a factor of 3 slower. Rapid degradation was observed for bromoxynil, explained mainly by photolysis. Besides the characterization and discussion of the experimental setup used, the rate constants obtained are discussed and compared with estimated values.

Aerosols↗
PubMed1998

Abiotic degradation of halobenzonitriles: investigation of the photolysis in solution.

This paper presents first experiments of laboratory investigations of the photodegradation by direct photolysis (lambda>290 nm) of cholorotahlonil, dichlobenil, chloroxynil, bromoxynil, and ioxynil in aqueous, pH-buffered, and organic solutions and the calculation of the quantum yields. The photolysis of chlorothalonil in water is low, with a corresponding low quantum yield (Phi=0.0001). Dichlobenil is photostable under the laboratory conditions used. The photoreactivity of bromoxynil and ioxynil was found to be comparable in aqueous solutions and about three times lower with respect to chloroxynil. The quantum yields obtained in water of chloroxynil, bromoxynil, and ioxynil are Phi=0.0060, 0.0093, and 0.0024, respectively. Half-lives of the pesticides in the environment with respect to direct irradiation are estimated using UV spectra and quantum yields as input variables obtained in the laboratory.

Benzamides↗
PubMed1996

A multiresidue method for determination of trace levels of pesticides in air and water.

A multiresidue analytical method is described for the analysis of 13 pesticides in fogwater, rainwater, gas, and particles. This method is based upon solid-liquid extraction using Sep-Pak tC18 light cartridges for aqueous samples, soxhlet for gas (adsorbed on XAD-2) and particles (on glass fiber filters), HPLC-based fractionation of the extracted residues using a silica column, and a linear gradient of n-hexane/tert butyl methyl ether followed by GC-ECD and HPLC-UV analyses of each fraction. Prior to analysis with GC-ECD, a methylation procedure using BF3/methanol was developed for the analysis of the fraction which contains chlorophenoxy acid herbicides. The recoveries of the extraction procedure of liquid samples and of the methylation were greater than 92 and 97% with a standard deviation lower than 8 and 5%, respectively. The detection limits varied between 0.1 and 0.01 microgram.ml-1 for the 13 pesticides studied with a standard deviation less than 9%. This method was used for the determination of pesticides in 18 fogwater samples (soluble + insoluble), 31 rainwater samples, and 17 air (gas + particles) samples collected between 1991 and 1993 in Colmar (east of France).

Air Pollutants↗
PubMed1996

[Study by questionnaire of the influence of weather conditions, particularly fog, on the symptomatology of asthmatic subjects].

The role of fog in the symptomatology in asthmatic subjects has been assessed by a questionnaire concerning respiratory complaints linked to meteorological conditions and to non-specific irritant factors. In a population of 121 asthmatics (59 men and 62 women) 74.4% complained that fog was a factor aggravating their symptoms while only 3% of a group of 30 non-asthmatic subjects expressed discomfort during episodes of fog. The chemical analysis of fog during 32 episodes of local fog (pH, chloride, nitrate, sulphate, sodium, ammonia, potassium, magnesium, calcium) has shown a greater concentration of pollutants and greater acidity in the smaller particles (2-6 microns) which are able to penetrate the bronchial tree. This acidity could explain the role of fog in respiratory physiology. Certain authors have suggested that the aggravation of respiratory symptoms observed during peaks of pollution could be induced by aerosols containing sulphuric acid while others have described effects on respiratory function at the time of exposure to acid aerosols in asthmatic subjects but the results of the different studies have not all been concordant. Putting aside the role of the susceptible individual, other factors may intervene at the time inhalation of pollutants, notably the ambient humidity, the neutralising effect of endogenous ammonia and the synergystic effect between acid aerosols and atmospheric pollutants.

Adolescent↗
PubMed1994

[Tobacco consumption among primary care physicians in the Autonomous Community of the Basque Province].

OBJECTIVE: To discover the tobacco consumption among Primary Care doctors in the Autonomous Community of the Basque Country. DESIGN: A crossover study by means of a telephone survey. PARTICIPANTS: 285 Primary Care doctors in the Autonomous Community of the Basque Country, obtained by systematic random sampling. RESULTS: Out of the 275 doctors who were finally surveyed, 32.1% smoked every day. 47.4% of doctors between 45 and 64 years old defined themselves as ex-smokers. CONCLUSIONS: The hypothesis can be ventured that Primary Care doctors are in the vanguard of giving up tobacco consumption.

Adult↗
PubMed1993

Postnatal development of the rat portal vein: correlation with occurrence of peptidergic innervation.

The portal vein of the rat is immature at birth, and is composed of an endothelium surrounded by undifferentiated cells of mesenchymal origin. Three days after birth, these cells have begun to differentiate and aggregate around the lumen to form two separate layers of perpendicularly oriented myoblasts, while a rich calcitonin gene-related peptide (CGRP) innervation is present around the vessel. In the internal circular muscle layer of the media myofibrils first develop on the endothelial side of the myoblasts, and then progressively reach the other side. In the longitudinal muscular layer of the media, which is separated from the circular layer by a connective lamina as early as 3 days after birth, myofibrils develop randomly in the cells. At the time of the enlargement of the longitudinal layer, long close contacts and intermediate junctions between external myoblasts and adventitial fibroblast-like cells were noted, suggesting that recruitment of this cell type is necessary for the maturation of the vessel wall. At about 28 days, the vein has reached its final structure and the smooth muscle cells are fully differentiated. The dense CGRP perivascular innervation already present at birth persists for the first 14 days of postnatal life when most of the cells have not yet acquired their complete contractile differentiation and are still capable of division. This innervation decreases transiently between 15-17 days, when the vessel acquires its spontaneous contractile activity, then rises to a peak between 20 and 25 days, and falls again. CGRP innervation, which is very scarce at 28 days, slowly increases during the peripubescent stage, by which time the adult structure of the vessel is established. Similar fluctuations in the density of peptidergic innervation were observed for substance P and neuropeptide Y, although these peptides were not yet present at birth and occurred only after 5 days. Vasoactive intestinal polypeptide- and bombesin-immunoreactive fibres were not found at any stage investigated. In addition to a description of the different cell-to-cell contacts which could play a role in the maturation of the vessel wall, we discuss the possible implication of the different peptides in the differentiation, maturation or maintenance of the vessel wall.

Animals↗
PubMed1992

Bright dawn simulation compared with bright morning light in the treatment of winter depression.

In a randomized cross-over design, 7 patients with winter depression were treated with a week of a bright (1700 lx) dawn simulation (0400 to 0600) and a week of standard bright (1700 lx) morning (0600 to 0800) light therapy. The Hamilton Rating Scale for Depression scores decreased significantly for the standard light therapy (18.9 to 6.6) but not for the bright dawn therapy (18.0 to 11.3). Early morning awakening was a frequent side effect with the bright dawn simulation. Although dawn simulation at a lower illuminance may be an effective treatment, the bright dawn used in this study showed only a nonsignificant trend to lower depression ratings. The illuminance of dawn simulation should be adjusted to minimize side effects.

Adult↗