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Biomedical subjects

D Maillard

Publications and source records attributed to D Maillard.

At least 19 recordsLinked to original sources
PubMed2004

The effects of a severe drought on mouflon lamb survival.

The mouflon population of Caroux-Espinouse, southern France, inhabits a highly seasonal area with dry summers. We monitored summer lamb survival during a severe drought in 2003, from early June to late August. The survival of 35 radio-tagged lambs over nine two-week periods was strongly affected by the timing of rainfall. Survival depended on the amount of rainfall recorded at a given 14 day period and in the previous 14-21 day period. Survival was not influenced by the exceptionally high mean daily temperature recorded during some periods. Male lamb survival (0.68) tended to be less than female survival (0.81), although not significantly, possibly because of a low sample size. The high lamb mortality (25.7%) recorded during a four-month period is much higher than previous estimates of first-year mortality (less than 10%). We recommend accounting for climatic variation in summer when studying the population dynamics of ungulates.

Analysis of Variance↗
PubMed2000

[Undergraduate medical education. Students' perspective and medical school policy].

OBJECTIVES: Student attendance to lectures in French medical schools is often poor. We surveyed undergraduate medical students in our medical school, repeating a similar survey conducted ten years earlier. The results are presented with the conclusions of the faculty seminar that followed this survey. METHODS: A closed item questionnaire was distributed in June, 1998, through the hospital wards where the students were posted. After two reminders, the final response rate was 71% (247/348). RESULTS: Overall, 71% of the students declared that they never, or only occasionally, attended lectures in the medical school. Reasons included lack of time (75%), the curriculum diverging from the program of the selective examination that gives access to graduate specialization programs (59%), or insufficient practical clinical content (36%); 46% believed that this teaching prepared them to practice family medicine (11% some specially), and 92% that the way it was organized was not compatible with preparing for the selective examination. On the other hand, 75% of the students in the final two years of the curriculum declared that attending regularly special preparation seminars for the selective examination, to succeed at this test (91%), but also to prepare for family practice (25%). Respectively, 75%, 68% and 66% declared that undergraduate medical courses should, ideally, prepare them for the selective examination, but also for the practice of family medicine, and for graduate medical education. CONCLUSIONS: These results echoed the difficulties of the faculty of the medical school to reconcile preparing students both for their future medical practice and for the selective examination. Two working groups were asked to identify independently appropriate educational objectives according to each perspective: their conclusions appeared to be quite compatible. Based on these conclusions, institutional objectives were ratified to guide the educational policy of our medical school, including the following: to reinforce the consistency and progressiveness of the curriculum; to promote active and autonomous student learning approaches; to develop faculty teaching skills, curriculum evaluation and recognition of teaching activities.

Curriculum↗
PubMed1999

Testing of the AVL OPTI 1 portable blood gas analyzer during inflight conditions.

The "AVL OPTI 1" (AVL Medical Instruments, Saint-Ouen l'Aumone, France), a completely automated portable blood gas analyzer, was chosen because of its accuracy under usual sea-level conditions and because of its new technology which broadens the possibilities for in-flight blood determinations: a) a single use cassette made of plexyglass containing the measurement chamber and the aligned sensors required for pO2, pcO2 and pH determination; b) calibration coefficients memorized in a bar code label fixed on the packing material; c) a quality control of each individual cassette prior to the measurement and at least once a day by two standard reference cassettes simulating high and low levels of pH, pcO2 and pO2; and d) a fully automatic introduction of the blood sample. The complete analytical cycle requires about 3 min with a sample volume of 80 microL of whole blood. After the measurement, the cassette containing blood sample is destroyed. Moreover, this device uses optical electrodes or "optodes" (fluorescence sensors). We tested the accuracy and imprecision of pO2 and pcO2 sensors on fresh blood which was equilibrated with four different gas mixtures at four different altitudes (250, 8000, 10,000 and 13,000 ft), simulated in a decompression chamber. Gas measurement optodes had linear responses and were accurate for all measured pO2 and pco2 values (n = 66), except for at high values of PO2 (>150 mmHg) and pco2 (>65 mmHg). The pressure value given by the AVL OPTI 1 was controlled before the experiment began and during the different depression levels. Barometric pressure results showed: a) concordance of pressure values with those of ground instrumentation; b) stable response; and c) absence of hysteresis. We conclude that the performance of the AVL OPTI 1 is satisfactory during inflight conditions.

Aerospace Medicine↗
PubMed1997

Pressure-heart rate responses to alpha-adrenergic stimulation and hormonal regulation in normotensive patients with obstructive sleep apnea.

Seven normotensive untreated patients with obstructive sleep apnea (OSA) and five control subjects without OSA were compared. Patients with cardiac dilation, chronic airflow limitation, liver and kidney disease, or diabetes mellitus were excluded. Change in pressure-heart rate relation to alpha-adrenergic stimulation (P-HRR), extracellular volume (ECV), and plasma volume (Vp) were measured during daytime. Plasma atrial natriuretic peptide (ANP), plasma renin and aldosterone concentrations were obtained at 1 hour intervals during the night. A mean apnea/hypopnea index (AHI) of 52.2 +/- 23.9/h and a mean lowest arterial oxygen saturation (SaO2) of 61.2 +/- 19.3% (mean +/- SD) were determined from polysomnographic monitoring in the patient group. Release of ANP was significantly higher during sleep in OSA patients than in control subjects (P < .01), with a maximum concentration between 4 and 6 AM in the former. Daytime ECV was significantly higher (P < .05) and Vp significantly lower (P < .05) in OSA patients. Night maximum concentration of ANP (max ANP) was negatively related to AHI (P < .05). P-HRR was negatively related to AHI (P < .05) and positively related to max ANP (P < .05). In conclusion, OSA syndrome alters hormonal system control of body fluid compartment regulation. The decreased response in night max ANP secretion in the most severe OSA patients could be explained by the smaller Vp observed in these patients, decreasing atrial and ventricular pressure loading. Furthermore, alteration of P-HRR, correlated to AHI and max ANP, strengthens the hypothesis that patients who develop hypertension are those in whom the protective mechanism of ANP release failed.

Adrenergic alpha-Agonists↗
PubMed1994

Fiberoptic bronchoscopy for the early diagnosis of subglottal inhalation injury: comparative value in the assessment of prognosis.

The aim of this study was to determine the value of bronchoscopy in the early diagnosis of inhalation injury. A total of 130 burn patients underwent bronchoscopy on admission to a specialized center. In order to validate the method and the bronchoscopist's conclusions, they underwent staged bronchial biopsies. Using the histologic findings as the "gold standard," bronchoscopy proved to be sensitive (sensitivity, 0.79) and highly specific (specificity, 0.94) for the diagnosis of inhalation injury. In addition, it was more reliable than the circumstances of the injury, the clinical findings, and complementary tests. In a one-dimensional analysis, bronchoscopy-proven inhalation injury was one of the most strongly predictive variables for the onset of ARDS and death. The analysis of survival curves confirmed that inhalation injury portends a bad outcome in burn patients. It was used to predict the likelihood of ARDS and death at the time of admission with a view to early specific treatment.

Adult↗
PubMed1993

Cost effectiveness of noninvasive oxygen saturation measurement during exercise for the diagnosis of Pneumocystis carinii pneumonia.

We assessed (1) the sensitivity and specificity of exercise oxygen saturation measurement (EOS) for the diagnosis of Pneumocystis carinii pneumonia (PCP); and (2) the cost of introducing this indirect diagnostic test compared with that of standard diagnostic strategies for PCP. In a prospective study, 85 HIV-infected patients with suspected PCP underwent EOS, followed by induced sputum (IS) and bronchoalveolar lavage (BAL) if IS was negative for P. carinii. The prevalence of PCP was 0.22, the sensitivity of IS was 0.6, and its specificity was perfect. The cost ratios of IS to BAL and EOS to BAL were 0.1 and 0.2, respectively. A desaturation of three points was the best cutoff point, giving perfect sensitivity and a specificity of 0.77. The cost analysis showed that the introduction of EOS into diagnostic strategies for PCP is highly justified when the local prevalence is low. Exercise oxygen saturation measurement is simple and safe, and the results are available rapidly; its sensitivity is perfect and its specificity good. Its economic utility depends on its cost and the local prevalence of PCP in the test population.

AIDS-Related Opportunistic Infections↗
PubMed1992

Effects of zolpidem versus diazepam and placebo on breathing control parameters in healthy human subjects.

The following study explores the possibility that zolpidem, a new hypnotic agent derived from imidopyridine, may induce changes in ventilatory function in normal subjects. The study, conducted double-blind on 16 subjects (eight men and eight women, aged 21 to 33 years) was undertaken in two successive phases: phase A with a cross-over, intended to compare the ventilatory effects of 10 mg oral dose of diazepam with a placebo, and then phase B, with a Latin square design, intended to compare the effects of 10 and 20 mg oral doses of zolpidem with 10 mg oral doses of diazepam and a placebo. Central inspiratory drive was assessed by occlusion pressure (P0.1) and breathing pattern in air and during carbon dioxide rebreathing. Measurements were performed one and three hours after each drug or placebo administration. Zolpidem did not affect tidal volume (Vt), slopes S1, S2 or P0.1, but decreased the duration of the phases of the respiratory cycle ti by 14% (p less than 0.01) and ttot by 15% (p = 0.03) after three hours post dosing without any change in ventilation, Vt/ti or ti/ttot. Nevertheless, these timing changes, although statistically significant, seem to have no clinical relevance to overall ventilation regulation in normal subjects. On the other hand, diazepam slightly changed S2 at three hours post dosing (0.14 +/- 0.07 versus 0.17 +/- 0.10 after the placebo; p = 0.06) without modifying the other parameters.

Administration, Oral↗
PubMed1991

Decreased oxyhemoglobin affinity in patients with sleep apnea syndrome.

Oxyhemogloblin affinity (P50 at pH 7.4, PaCO2 = 40 mm Hg, temperature = 37 degrees C) and 2,3-DPG concentration were assessed in 15 nonsmokers (14 men and one woman 46 to 63 yr of age) with sleep apnea syndrome (SAS) and in 10 normal subjects (eight men and two women 22 to 48 yr of age). In patients with SAS, mean nocturnal apnea index was 46 +/- 20/h, and mean nocturnal SO2 was 86 +/- 6% versus 94.6 +/- 1.8% during the daytime. Daytime mean P50 of the patients was 28.5 +/- 1.2 mm Hg versus 27.1 +/- 0.3 mm Hg in the normal subjects (p less than 0.05). Daytime mean 2.3-DPG was 1.23 +/- 0.25 moles DPG/mole hemoglobin versus 0.80 +/- 0.15 (p less than 0.05). Significant correlations were found in patients between P50 and mean nocturnal SO2 (r = -0.62, p less than 0.01) and between P50 and 2,3-DPG (r = 0.68, p less than 0.01). The measurements were repeated in five patients after surgical or positive-pressure treatment. P50 and 2,3-DPG both decreased and returned to normal values. In conclusion, the oxyhemoglobin dissociation curve is shifted to the right in patients with SAS and there is an increase in 2,3-DPG. These could be protective mechanisms against the development of polycythemia, pulmonary hypertension, and cor pulmonale.

2,3-Diphosphoglycerate↗
PubMed1990

Ventilatory adjustments during sustained resistive unloading in exercising humans.

Effect of He-O2-breathing (79.1%:20.9%) compared to air-breathing on inspiratory ventilation (VI) and its different components [tidal volume (VT), the duration of the phases of each respiratory cycle (tI, tTOT)] as well as on inspiratory mouth occlusion pressure (P0.1) were studied in six normal men at rest and during 72 constant-load exercises (90 W) over a much longer period than in previous studies. Results showed that, irrespective of the order of administration of the two gases (7 min air----7 min He-O2 or vice versa): at rest, P0.1 decreased during He-O2 inhalation but no changes in VI and breathing pattern were detectable; during exercise, sustained He-induced hyperventilation was observed without any change in the absolute value of P0.1; increase in P0.1 between the resting period and exercise (delta P0.1) was significantly higher during He-O2-breathing than during air breathing; this He-induced hyperventilation was associated with a sustained increase in VT/tI, but with constant tI/tTOT. Helium-breathing during exercise cannot be a simple situation of resistance unloading, as has been suggested. We conclude that He-O2-breathing, after the initial compensation period, induces reflex changes in ventilatory control with an increase in inspiratory neural drive. Moreover, it appears that exercise P0.1 is not a legitimate index of inspiratory neural drive whenever rest P0.1 changes according to the nature of the inhaled gas mixture.

Adaptation, Physiological↗
PubMed1989

Protective effect of vasodilators on liver function after long hypothermic preservation: a study in the isolated perfused rat liver.

The effects of two vasodilators, papaverine and pentoxifylline (a methylxanthine derivative), on liver function after 19 hr hypothermic preservation were investigated. Hypothermic preservation was performed according to the standard technique, and liver hemodynamics and function were studied during 70 min immediately after reperfusion in an isolated perfused rat liver system. No significant changes occurred after hypothermic storage for 5 hr. However, when the storage was prolonged to 19 hr, bile flow and taurocholate intrinsic clearance were significantly reduced; transaminase release was markedly increased and histological studies demonstrated centrilobular necrosis. Concomitantly, liver blood flow was significantly reduced and intrahepatic vascular resistance was increased. Papaverine and pentoxifylline administered during preservation and at the time of reperfusion significantly improved all parameters. The improvement was more pronounced after pentoxifylline, and this group showed no significant difference in any of the studied parameters from the control livers. The results show that two vasodilators significantly protect the liver during long hypothermic preservation. The data suggest that abnormalities of liver microcirculation are of major importance in the pathogenesis of liver injury after hypothermic storage.

Animals↗
PubMed1989

The determination of total haemoglobin as haemiglobin.

This study describes a new method for routine total haemoglobin determination by conversion to haemiglobin (Hi), and compares it with the haemiglobin cyanide (HiCN) method. Experiments were performed in two phases. Firstly, the absorbance coefficient (epsilon Hi,500mm) at pH = 6.8, determined from 24 blood samples, was found to be 998 +/- 31 m2.mol-1. Secondly, using this value of epsilon, the range of haemoglobin concentration measured was 3.7 to 19.2 mmol.l-1 (6 to 31 g.dl-1). The correlation data shows an excellent correlation (r = 0.982, p less than 0.001) with the reference procedure. Reproducibility and accuracy were shown to be good.

Evaluation Studies as Topic↗
PubMed1988

Testing of the Eschweiler 2500-11 blood gas analyser during inflight conditions.

Measurement of blood gas values during air transport of intensive care patients must take into account the extreme inflight variations in pressure. We tested the accuracy and reliability of the Eschweiler 2500-11 apparatus, with its incorporated pressure transducer, on four different gas mixtures equilibrated with fresh blood at two different altitudes simulated in a decompression chamber. Results for the pressure transducer show: 1) concordance of pressure values with those of ground instrumentation; 2) stable response; and 3) absence of hysteresis. Gas measurement electrodes were shown to have linear responses and were accurate for all tested values except very low PCO2 and very high PO2 figures. We conclude that the performance of this device is satisfactory during inflight conditions.

Aerospace Medicine↗
PubMed1985

[Spirometric monitoring of the effects of puncturing thoracic pain points in asthmatic disease].

The effects of puncture of thoracic pain points on ventilatory abnormalities were studied in 17 asthmatic subjects. For the tested group (n = 8), the painful character of the points was the only criterion for the choice of puncture sites. References to classical acupuncture points were not made. The points chosen for the control group (n = 9) were in extrathoracic zones (lower limbs). VEMS was significantly higher (p less than 0.05) after puncture of thoracic pain points whereas no shift was observed after puncture in the extrathoracic zone. VC was not modified by either technique.

Acupuncture Therapy↗
PubMed1985

[Value of a brief ergometric test in the functional evaluation of chronic bronchopneumopathy].

The purpose of this work was to study the usefulness of short muscular exercise as part of standard respiratory function testing. A group of 19 patients with chronic bronchitis performed moderate load exercise (30 to 60 watts) on a cycle ergometer for 10 mn. Blood gases and acid-base balance were measured at rest, at the 2nd and the 10th mn of pedaling. In spite of highly significant relationships between resting values (blood gases, spirometry) and exercise data (blood gases), the scattering of the results precludes predicting the latter from the former. In contrast, the comparison between each of the two exercise results (2nd and 10th mn) shows not only a highly significant correlation but also a standard deviation to the regression lines which is objectively diminished. Thus, muscular exercise seems to give specific information that could be a useful component of respiratory function testing. Further, blood gas results obtained at the 2nd mn of muscular exercise suffice, thus obviating the need for a longer exercise programme that might be badly tolerated by patients.

Acid-Base Equilibrium↗
PubMed1984

[Cholesterol crystals and biliary lithiasis. Importance of the study of bile collected by duodenal intubation].

Cholesterol crystallization in a necessary step in the formation of cholesterol gallstones. Our purpose was to study the relationship between the presence of biliary cholesterol crystals and radiolucent gallstones. Bile was obtained by duodenal intubation from 60 subjects free of hepatic disease: 40 patients had radiolucent gallstones and in the remaining 20 subjects no gallstones could be found either by oral cholecystography or by ultrasound examination. In each patient a bile sample was used to search for cholesterol crystals; in another sample, biliary cholesterol, phospholipids and bile acids were measured to calculate the lithogenic index. Among the 44 subjects with lithogenic bile, 34 had radiolucent gallstones. Twenty-two out of the 60 patients had both cholesterol crystals and radiolucent gallstones; 21 subjects out of the 22 had lithogenic bile. In patients with frequent biliary colic or subacute pancreatitis without visible gallstones, finding cholesterol crystals in bile might suggest medical or surgical specific treatment.

Adult↗
PubMed1983

Depressive effect of coughing on spinal monosynaptic reflexes in conscious man.

1. The relationship between coughing and spinal monosynaptic reflexes (SMR) in extensors and flexors was investigated in eight healthy subjects by using the Hoffmann technique. Coughing exerted major depression (81% in extensor and 83% in flexor SMR). This depressant effect began simultaneously with the first cough and lasted through the coughing phase. Complete recovery to initial values occurred an average of 40 s thereafter. 2. In comparison, mental tasks induced only a slight decrease in SMR amplitude. In contrast, the Mueller and Valsalva manoeuvres induced facilitation. 3. During coughing, large variations in extensor amplitudes were observed that were coupled with the ventilatory cycle. Slight facilitation was observed during inspiration, but expiration induced pronounced depression, occurring 0.20 s after the beginning of the expiratory period. Experiments performed during baseline breathing failed to show any change throughout inspiratory or expiratory phases. 4. Chemical stimulation of irritant receptors (inhalation of citric acid) produced no specific modification of extensor responses compared with the effect of placebo inhalation (distilled water). 5. These data suggest that coughing exerts a major depressant effect on motor activity via a loop that possibly includes cardiopulmonary receptors and inhibitory supraspinal descending pathways.

Adult↗
PubMed1981

Gas exchange during bicycle exercises preceded or not by loadless pedalling in female and male subjects.

The effects on ventilation and oxygen uptake of pedalling with no load on the ergometer before exercise have been investigated in 10 subjects (6 males and 4 females). It has been found that: (1) the O2-deficit calculated at the beginning of exercise is less variable and generally reduced when exercise has been preceded by a loadless pedalling period; (2) for a given steady-state VO2, the O2-deficit is larger in female than in male subjects; (3) the respiratory equivalents for oxygen and for carbon dioxide are not affected by loadless pedalling; they are generally larger in female than in male subjects; (4) the increase in ventilation at the beginning of exercise is smaller after loadless pedalling but this seems to be apparent only in male subjects; (5) the pattern of breathing and heart rate are not affected by loadless pedalling. It is concluded that pedalling with no load on the ergometer before the exercise prepares the subject to deliver oxygen more rapidly to the muscles. It then reduces the variability in gas exchanges and the O2-deficit. Several factors which may account for this better efficiency of oxygen delivery are discussed.

Adult↗