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Biomedical subjects

B Massonnet

Publications and source records attributed to B Massonnet.

15 recordsLinked to original sources
PubMed2004

Patterns of genetic differention between populations of the specialized herbivore Macrosiphoniella tanacetaria (Homoptera, Aphididae).

For herbivorous insects, studies of isolation by distance (IBD) are available for large spatial scales, whereas studies over small geographic distances are relatively rare, in particular for species where population turnover is high. In this study, we investigated IBD and population genetic structure in the aphid Macrosiphoniella tanacetaria, a specialist herbivore of tansy (Tanacetum vulgare). Owing to clonal growth, an individual plant (genet) has one to many shoots (ramets), which can host aphid colonies. Both at the level of ramets and genets, aphid persistence is short, in the order of weeks. Sampling of 17 populations was performed on a logarithmic scale, along the Saale River in Germany in June 2001, with distances between populations ranging from 1 m to 170 km. For the six microsatellites used, allelic and genotypic variability within aphid populations was high, and deviations from Hardy-Weinberg equilibrium and linkage disequilibrium were frequent. Most pairs of populations were significantly differentiated but there was no pattern of IBD. However, including into the analysis four additional populations from Alsace, France, collected at distances of, on average 470 km, resulted in a weak but significant IBD. Aphids are passive dispersers that are known to occasionally disperse over large distances, even though most dispersal is likely to occur over a small spatial scale. We suggest that for the host-specific M. tanacetaria, patterns of genetic variation among populations are, at an ecologically meaningful scale, governed by colonization/extinction dynamics and genetic drift rather than by a drift-dispersal equilibrium.

Animals↗
PubMed1997

[Respiratory function surveillance during prolonged treatment with low-dose methotrexate].

Long-term low-dose methotrexate (MTX) has a proven beneficial effect in patients with rheumatoid arthritis; the main drawback being the risk of interstitial pneumonia. Although estimations have varied, in our recent prospective analysis we observed 4 cases among 124 receiving MTX for rheumatological disorders, i.e. a risk rate of 3.2% Age, sex, disease duration, administration route and daily or cumulative dose do not appear to affect risk, but recent work suggest that renal failure, concomitent use of nonsteroid anti-inflammatory drugs, smoking, past pulmonary history or radiographic anomalies as well as recent withdrawal of corticosteroids are risk factors. Pulmonary function tests can be used to detect acute disorders and regular testing has been proposed to help predicted pulmonary complications in patients receiving long-term MTX. Unfortunately, minimal variations observed to date, for example in forced vital capacity or expiratory volume, do not appear to occur prior to clinical manifestations and may be due to normal aging processes or the pathological effect of the rheumatoid disease itself. In addition, due to the proven efficacy of MTX, randomized trials against a control group not given MTX would be ethically unacceptable. We are thus still unable to predict development of secondary pulmonary complications to long-term low-dose MTX. We therefore recommend testing pulmonary function at treatment onset to establish a reference for subsequent tests performed in case of clinical manifestations during MTX therapy. Patients should be counselled to consult in case of pulmonary symptoms in order to allow diagnosis as early as possible. The most recent data also would suggest that MTX may induce infraclinical alterations of pulmonary function although their significance remains to be clarified.

Antirheumatic Agents↗
PubMed1996

Pulmonary function in patients receiving long-term low-dose methotrexate.

STUDY OBJECTIVE: Acute interstitial pneumonitis is the main pulmonary side effect during methotrexate (MTX) treatment for rheumatoid arthritis. The aim of the study was to determine the following: (1) the incidence of MTX-induced pneumonitis during low-dose long-term MTX treatment for chronic arthritis; (2) whether periodic pulmonary function tests were useful for detecting MTX pneumonitis before clinical symptoms; and (3) whether any subclinical abnormality of pulmonary function was present in asymptomatic patients receiving MTX treatment. DESIGN: Pulmonary function tests, including diffusing capacity for carbon monoxide (DCO) measurements, were performed in 124 patients receiving low-dose MTX for rheumatologic diseases at the time of initiating treatment, and then at 3 months, 6 months, and at 6-month intervals thereafter. Mean duration of treatment was 23 months. RESULTS: MTX treatment was interrupted in six patients for acute onset of clinical symptoms; criteria for diagnosis of MTX pneumonitis were fullfilled in four cases (incidence: 3.2%); no risk factor could be identified. No significant decrease in pulmonary function parameters could be observed before the onset of clinical symptoms of MTX pneumonitis, and this adverse effect could not be predicted by periodic function tests. A statistically significant decrease was found in FVC (-2.2%, p=0.04), FEV1 (-5.0%, p<0.001), and diffusing capacity per alveolar volume, DCO/VA (-4.8%, p=0.03), but not DCO (-1.3%, p>0.05), in the 118 other asymptomatic patients during MTX treatment. CONCLUSION: We found minor subclinical alterations in pulmonary function in asymptomatic patients receiving low-dose long-term MTX treatment, but periodic pulmonary function tests did not allow us to detect MTX-induced pneumonitis before clinical symptoms. Therefore, we recommend that these tests should not be systematically performed while patients are receiving treatment.

Adult↗
PubMed1988

[Mucociliary function of 10 patients with ankylosing spondylarthritis with normal lung radiographs].

Bi-apical pulmonary fibrosis particular to ankylosing spondylitis is found in 1 to 10% of cases. The non-specific fibrosis or fibrosis of a more specific character such as iritis or the aortic disease are discussed. The fibrosis may be provoked by repeated infections which would favour an eventual hypoventilation at the apices secondary to the rigidity of the thoracic cage. To test this hypothesis we have studied muco-ciliary clearance in 10 subjects presenting with ankylosing spondylitis without any pulmonary radiological lesion and have compared these to 7 control subjects. No statistical difference was found in the clearance rate between the control subjects and the patients on the one hand (whether or not they had extra articular manifestations) and between the different areas of the lung (notably superior and inferior) in patients on the other hand. Thus this bi-apical fibrosis does not seem to explain the phenomena repeated infections at the apices which might have been favoured by any secondary deficiency in muco-ciliary clearance and hypoventilation of the apices. It seems most likely that the fibrosis has a specific origin related to the nature of the disease.

Adult↗
PubMed1985

[Tracheobronchial clearance in the hypersecreting asthmatic patient].

Tracheo-bronchial clearance in the hyper-secreting asthmatic patient was studied by observing the elimination over a period of time of a tracer placed on the bronchial wall over time. The authors describe the method used. The analysis of the results enables two purification processes to be distinguished: muco-ciliary activity and cough. The reliability of the method enabled comparison of the results obtained in 7 healthy subjects and 11 hyper-secreting asthmatics. In the healthy subjects, clearance is carried out by the muco-ciliary activity. In the asthmatics, global clearance is normal, but the cough plays an essential role as the muco-ciliary activity is decreased. The question then arises as to whether the decreased muco-ciliary activity in asthmatic patients is due to failure of the bronchial cilia or to the mucus.

Adult↗
PubMed1980

[Pathology of thermoregulation].

Though the same symptoms are observed in either hyper- or hypothermia, the etiology may be of four different types: 1) the thermoregulatory mechanisms may be insufficient to adapt to temperature extremes in normal subjects; 2) there may be modifications in peripheral thermoregulatory responses, when the patient compensates for the deficiency or excess by other thermoregulatory responses: the internal temperature is then not distrubed but is not stable; 3) a central lesion causing loss of ability to oppose low temperatures results in hypothermia with coma as soon as the subject is exposed to cold. Loss of ability to oppose heat is not encountered: it is superimposable on the hyperexcitation of the centers that oppose heat; 4) modifications in thermoregulatory responses are mainly evident as fever, a protective defense reaction of the organism wich should be supported rather than fought. The inverse syndrome, if it exists, is difficult to distinguish from the loss of ability to oppose cold. The term of "anapyrexia" is suggested for this latter condition. Whatever the diagnosis, measurment of rectal temperature is insufficient for diagnosis, and thermoregulatory responses have to be evaluated. Therapy for the same symptom may, in fact, be inversed depending on the etiology. It may well be that thermoregulatory function is poorly understood because of its true importance. Possessing no specific organs, it uses the various reactions that have appeared during phytogenetic development to ensure thermal homeostasis. It acts permanently through multiple, independent, regulatory loops allowing many compensatory mechanisms. This underlines, in an indirect manner, the need for the organism to maintain at all costs a constant temperature. This permanent thermal homeostasis implies that only severe disorders result in hyper- or hypothermia, that major disturbances are rapidly fatal, which emphasizes the fundamental importance of thermorgulation.

Adult↗
PubMed1980

[Salivation during hyperthermia in human beings (author's transl)].

In numerous species, saliva secretion is an important thermolytic response to hyperthermia. The aim of the present work was to look for a thermolytic saliva secretion in human beings. Saliva collected by cannulation was not secreted more during active or passive hyperthermia than during control periods. Therefore, it can be concluded that saliva secretion has no thermoregulatory role in human beings.

Body Temperature Regulation↗
PubMed1977

[Initial assessment of a behavioural therapy anti-tobacco programme (author's transl)].

The principle of behavioural therapy was used in anti-tobacco treatment. An assessment of the first 100 patients is given here. From the beginning of treatment, which was individual and lasted for one week, the subjects, with three exceptions, stopped smoking between the treatment sessions. After treatment was completed, 93 subjects maintained this abstinence for at least 15 days; 74 patients have not started to smoke again, with a follow-up period ranging from 2 to 18 months. The degree of motivation of the patients would seem to be the only parameter related to relapse.

Adult↗
PubMed1977

Thermoregulatory responses as a function of core temperature in humans.

1. Six healthy humans were immersed sequentially in baths maintained at a steady temperature of either 28 +/- 1 or 38-8 +/- 1 degree C. 2. Metabolic heat production was calculated by respiratory gas analysis. A ventilated capsule was placed on the forehead and sweat secretion was calculated from psychrometric recordings. Convective heat loss from one hand to water-perfused glove provided a continuous measurement of vasomotor response. 3. Heat production, sweating, and vasomotor heat loss were proportional to core temperature. 4. Sweating and vasomotor response were parallel. Vasoconstriction was complete, before the onset of shivering. 5. The thresholds for heat loss and heat production were superimposed, without a 'dead band' core temperature.

Body Temperature↗
PubMed1976

A study of the nycthemeral cycle of behavioural temperature regulation in man.

1. Four human subjects were rendered hyperthermic and hypothermic by immersion in warm and cool water, at 02.00, 08.00, 14.00 and 20.00 hr. Bath and oesophageal temperatures and pulse rate were recorded. Temperature preference was determined by operant behaviour and vote. The core temperature set-point for behavioural thermoregulation was estimated from the behavioural results. 2. The results are in accord with those of previous studies of the nyethemeral cycling of autonomic responsiveness to heat and cold with a heating up phase before noon and a cooling down phase during the early night. 3. Subjective sensations and behavioural responses were also found to follow a nycthemeral cycle with a minimum before noon and a maximum at 20.00 hr. 4. The core temperature set point was 0-7 degrees C higher after noon than before noon with a small phase advance from resting core temperature. This result suggests that the nycthemeral cyclic change in body temperature is due to a nycthemeral cyclic change in the set-point near to which body temperature is kept by both autonomic and behavioural thermoregulatory responses.

Behavior↗
PubMed1974

Temperature regulation during fever: change of set point or change of gain? A tentative answer from a behavioural study in man.

1. Four subjects were immersed in a stirred water-bath maintained at either 30 or 40 degrees C. The left hand was placed out of the bath in a glove receiving water at a temperature selected by the subject as most pleasurable. Experiments were conducted during the euthermic state and during either spontaneous or induced fever.2. The results of control experiments confirm a previous observation using the same method, that preferred hand skin temperature was a linear function of internal temperature but also indicated an influence by mean skin temperature.3. The general pattern of response during fever was identical to that when fever was absent except that the regulated steady state internal temperature was higher and the slopes of preferred temperature plotted against internal temperature were steeper.4. The results seem to support the concept of a change in set point rather than that of a change in the gain of the thermoregulatory processes during fever.

Behavior↗