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Biomedical subjects

J Malo

Publications and source records attributed to J Malo.

At least 19 recordsLinked to original sources
PubMed1998

Spectral analysis of wakefulness and REM sleep EEG in patients with sleep apnoea syndrome.

Neuropsychological investigations of patients with obstructive sleep apnoea syndrome (OSAS) have shown impairments in such basic functions as memory, attention and executive control. Since executive functions are known to be dependent on the integrity of the frontal lobe, it was hypothesized that OSAS may be associated with hypoxaemic frontal lobe dysfunction. To test this hypothesis, 21 apnoeic patients and 10 normal controls were studied with quantitative electroencephalographic (EEG) methods during rapid eye movement (REM) sleep, when most apnoeic events occur and during wakefulness. In apnoeic patients, EEG slowing in REM sleep was observed over frontal, central and parietal regions, while EEG slowing during wakefulness was observed over all cortical regions examined. A positive correlation was found between EEG slowing during wakefulness and oxygen desaturation during the night. Contrary to the hypothesis, these electroencephalographic changes were not localized only to the frontal region. This result may explain the wide range of neuropsychological deficits noted in patients with obstructive sleep apnoea syndrome, in addition to their poor performance in tasks of executive functioning.

Adult↗
PubMed1997

Implementations of a novel algorithm for colour constancy.

In agreement with the principles of the relativistic model proposed by Creutzfeldt et al., with the photometric rule (lightness anchoring rule) and with the influence of simultaneous contrast in the appearance of a visual scene, we propose a first-stage mechanism yielding substantial colour constancy. We have defined a set of first-stage colour descriptors, and to test their utility, we have performed a simulation using a Machine Vision System (MVS). The statistical stability of the descriptors for Munsell samples under different illuminants is good.

Algorithms↗
PubMed1997

The impact of paternal alcoholism and maternal social position on boys' school adjustment, pubertal maturation and sexual behavior: a test of two competing hypotheses.

Two competing hypotheses concerning the effects of stressful environments on the onset of puberty were tested using longitudinal data for a sample of boys from low socioeconomic backgrounds. Paternal alcoholism and maternal social position were used as indicators of family stress. School placement was monitored from school entry to 14 years of age. Teachers rated the boys' disruptive and anxious behaviors, while the boys reported on parenting behaviors at 10 years of age. Pubertal maturation, age of first sexual intercourse and sexual behavior were assessed between 11 and 14 years of age. The prepubertal data indicated that boys with an alcoholic father, or a mother from a low social position, were more stressed and had more behavior problems: the boys with alcoholic fathers perceived their parents as being more punitive, and as setting fewer rules concerning their behavior; those who had at least one maladjusted parent were more often placed out of an age-appropriate regular classroom, and were rated more disruptive and more anxious by their teachers. Paradoxically, the results for the onset of puberty gave support to the two rival hypotheses. Paternal alcoholism led to a delay of male pubertal onset, as suggested by the hypothesis that stress activates the hypothalamic-pituitary-adrenal axis, and inhibits the hypothalamic-pituitary-gonadal axis. However, sons of alcoholic fathers had more frequent sexual intercourse and more sexual partners, as suggested by the evolutionary theory of socialization. High maternal social position acted as a protective factor for school placement of boys with an alcoholic father. These results challenged a key hypothesis of the evolutionary theory of socialization for males. They indicated that the link between childhood family environment, behavior development, pubertal maturation and sexual promiscuity are more complex than anticipated.

Adolescent↗
PubMed1997

Standard criterion for fluctuations of modulation transfer function in the human eye: application to disposable contact lenses.

It is well known that the modulation transfer function (MTF) characterizes the optical quality of the eye. Recently, some objective techniques have been introduced in order to measure this function in vivo. These techniques could be employed to display the temporal fluctuations of the eye + compensation system and to isolate the effect of the compensation element provided that the standard fluctuations for a normal observer were known. In this work we carry out a study of the MTF of the human eye over a long period of time to quantify the standard fluctuations of the retinal image quality and to establish a standard criterion of normality. We have defined a single quality parameter from each measured MTF to simplify the analysis of the results. We have evaluated this merit function on normal observers three times a day for one month. As expected, random deviations from the mean value of the merit function have been obtained, although fluctuations with no statistical differences of the merit function (P value from ANOVA test P > 0.01) and the standard deviation of these fluctuations (5%) can be chosen as a standard criterion. We have used this result to study the behaviour of a time-varying compensation element: a disposable contact lens. The study of the eye + contact lens system has been carried out with four types of disposable contact lenses for one month. In spite of their generally good behaviour, statistically significant differences from the standard pattern can be observed. This superimposed continuous fluctuation can be due to lens-dependent processes.

Contact Lenses↗
PubMed1996

Introduction of a New Coaxial Falloposcopy System

Coaxial falloposcopy is a transcervical approach to visualizing the entire fallopian tubal lumen from the uterotubal ostium (UTO). To eliminate bulky camera attachments and poor image quality, a new falloposcopy system was developed with a small articulating-tip hysteroscope, stabilizing device to maintain UTO alignment, flexible coaxial catheter and guidewire, and 0.4-mm outer diameter falloposcope with enhanced fiberoptics. We used the instrument in 23 women with a diagnosis of proximal (PTO) or distal (DTO) tubal obstruction (group 1, 16 patients, 30 tubes) or unexplained infertility (group 2, 4 patients, 7 tubes) after previous hysterosalpingogram or laparoscopy. Successful cannulation was achieved in 31 (83.3%) of 37 tubes. Fibrosis of the UTO prevented access to two tubes. In group 1, 14 of 23 tubes with presumed PTO were patent and normal at falloposcopy. In group 2, pathology was present in two of seven tubes. A false positive diagnosis was made in 61% of tubes with presumed PTO and false negative diagnosis in 29% of presumably normal tubes. Coaxial falloposcopy is an effective means of assessing the tubal lumen and should become a more routine part of infertility evaluations.

Journal Article↗
PubMed1993

Persistent neuropsychological deficits and vigilance impairment in sleep apnea syndrome after treatment with continuous positive airways pressure (CPAP).

The obstructive sleep apnea syndrome is characterized by nocturnal sleep disturbance, excessive daytime sleepiness and neuropsychological deficits in the areas of memory, attention, and executive tasks. In the present study, these clinical manifestations were assessed in apneic patients before and 6 months after treatment with nasally applied continuous positive airway pressure (CPAP). CPAP treatment was found to restore normal respiration during sleep and to normalize sleep organization. Daytime vigilance greatly improved with treatment but some degree of somnolence as compared to normal controls persisted. Similarly, most neuropsychological deficits normalized with treatment. The exception was for planning abilities and manual dexterity, two neuropsychological deficits that have been found to be highly correlated with the severity of nocturnal hypoxemia. These results raise the possibility that anoxic brain damage is a pathogenic factor in severe obstructive sleep apnea syndrome.

Adult↗
PubMed1991

Obstructive sleep apnea syndrome: pathogenesis of neuropsychological deficits.

Neuropsychological deficits have been documented in patients with obstructive sleep apnea syndrome (OSAS). Both nocturnal hypoxemia and impairement of daytime vigilance have been suggested as the pathogenesis of these deficits, yet it remains difficult to find good correlations between cognitive deficits and either of these physiological parameters. In the present study, 10 normal controls were compared to 10 moderately and 10 severely apneic patients, all recorded in a sleep laboratory for two consecutive nights, with a vigilance and neuropsychological assessment made during the intervening day. Relative to the controls, moderate and severe OSAS showed differences in many cognitive functions, although the severely affected showed the greater differences. Moreover, severe apneics were also worse than moderate apneics on tests that were found to be normal in the latter group. This suggests a discontinuity in the appearance of neuropsychological deficits as OSAS progresses. Further analyses revealed that reductions in general intellectual measures, as well as in executive and psychomotor tasks were all attributable to the severity of hypoxemia, while other attention and memory deficits were related to vigiance impairment. Therefore, both vigilance impairment and nocturnal hypoxemia may differentially contribute to the cognitive dysfunctions found in OSAS.

Adult↗
PubMed1991

Nocturnal hypoxemia as a determinant of vigilance impairment in sleep apnea syndrome.

In sleep apnea syndrome (SAS), vigilance impairment is typically associated with highly disrupted sleep, but recently, nocturnal hypoxemia has also been identified as a second pathogenetic factor in patients with a high degree of desaturation. However, although sleep disruption has been demonstrated to play a role in both the propensity to fall asleep and the capacity to stay awake, the role of nocturnal hypoxemia has been implicated only in the latter. In the present study, both sleep disruption and nocturnal hypoxemia were assessed in 20 moderately to severely apneic patients. During the day, vigilance was assessed both by the multiple sleep latency test (MSLT), as a measure of the propensity to fall asleep, and by the four-choice reaction time test (FCRTT), as a measure of the capacity to stay awake in a performance task. Severity of nocturnal hypoxemia was found to predict performance on the MSLT, as well as on the FCRTT, but sleep disruption was found to predict performance only on the FCRTT. These results suggest that in moderately to severely affected SAS patients, nocturnal hypoxemia may play a primary role in the pathogenesis of vigilance impairment.

Adult↗
PubMed1991

[The effect of continuous peri-thoracic negative pressure on nocturnal desaturation of chronic obstructive bronchopneumopathies].

The fall of functional residual capacity (FRC) in the genesis of nocturnal desaturation in chronic airflow obstruction (COPD) continues to be discussed. This hypothesis is being tested by applying a negative continuous thoracic pressure using a cuirass/poncho attached to a pump for one night (night II) after a control night with a cuirass/poncho at atmospheric pressure (night 1). Seven subjects with a mean age of 61 +/- 9, with a mean weight of 108 +/- 21% of their ideal weight, who were suffering from severe airflow obstruction with a mean forced expired volume (FEV1: 39 +/- 20% th., FEV1/FVC: 35 +/- 9%, PaO2: 60 +/- 3 mmHg, PaCO2: 42 +/- 4 mmHg). These seven subjects had two polysomnographies on the two successive nights. During night II, the FRC was increased by 0.33 +/- 0.6 L by applying a continuous negative thoracic pressure of 10 +/- 1 cm of water. A significant decrease in the sleep time was noted (248 +/- 86 min vs 316 +/- 74 min, p less than 0.02) also the efficacy of sleep (54 +/- 9% vs 71 +/- 15% vm p less than 0.02). There was no difference between the two nights as regards the distribution of the sleep stages. In 2 subjects, the hypopnoea-apnoea index passed from 0 to 11 and from 4 to 22 respectively. The principal result was the absence of any significant difference in mean nocturnal oxygen saturation between the two nights.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1990

Acute lung reaction due to zinc inhalation.

A 27-yr-old man began work at a company that produces concrete pipes in April 1987. The pipes are linked with rings covered with zinc. In September 1987, he was transferred to a new job in the same plant where he had to heat zinc wires and shoot the heated zinc in powder form onto the iron rings. He had no past personal nor family atopic history. Two weeks after he began in his new job, he experienced an episode of chills with muscle aches and dyspnoea at the end of a working day. The fever persisted until the next day, at which time he saw a physician. A chest radiograph revealed diffuse interstitial shadows. He was off work for 10 days. His symptomatology disappeared and his chest radiograph cleared. He went back to work and experienced a similar episode. He remained away from work for one month, after which specific inhalation challenges were performed. On a control day, there were no significant changes in forced expiratory volume in one second (FEV1), forced vital capacity (FVC), or buccal temperature. Two white blood counts (WBC) showed 8,400 and 8,500 white cells. He was exposed to his usual work environment for one hour on two consecutive days. On both occasions, there were significant falls in FEV1 (16% and 20%) and FVC (10% and 11%), occurring 4-6 h after exposure. Buccal temperature reached 38.1 and 38.7 degrees C on the two occasions, and WBC were 17,000 and 15,900 at the end of each day. Precipitins were negative and specific IgG antibodies could not be detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1989

Bronchial hyperresponsiveness to inhaled methacholine in subjects with chronic left heart failure at a time of exacerbation and after increasing diuretic therapy.

Cough and wheezing are common findings in left heart failure. However, it is still questionable whether nonallergic bronchial hyperresponsiveness, the hallmark of asthma, is also associated with this condition. In 12 subjects with acute decompensation of chronic postischemic LV failure, we assessed the PC20 methacholine during an episode of acute LV failure and after five to 15 days of intensive diuretic therapy. Weight, arterial blood gases, plethysmographic lung volumes, and expiratory flows were also measured on both visits. Extravascular lung water was estimated indirectly with a radiologic score. During acute decompensation, six subjects had significant airway obstruction and eight had a PC20 less than or equal to 16 mg/ml (significant bronchial hyperresponsiveness). After diuretic therapy, subjects improved significantly, losing an average of 2.2 kg, but they still had chronic LV failure and evidence of an obstructive breathing defect. Although mean PC20 was unchanged, three subjects had significantly improved PC20 after treatment. We conclude that: (1) left ventricular failure is often associated with mild bronchial hyperresponsiveness, although it is not excluded that smoking and the resulting possibility of bronchial obstruction can also play some role; and (2) acute treatment does not generally alter bronchial responsiveness to methacholine, suggesting that chronic LV failure can cause chronic changes to the airways.

Aged↗
PubMed1987

Mortality and morbidity related to severe intrapulmonary shunting in multiple trauma patients.

Of 210 multiple trauma patients admitted to our Intensive Care Unit (ICU), 12 (5%) presented with severe hypoxemic respiratory failure needing mechanical ventilation with an FIO2 of 1.0 because of severe intrapulmonary shunting (IS). Five (42%) of these patients survived and two (17%) died because of their underlying respiratory failure. We found a mean of three etiologic factors in each patient to account for their IS. Nonsurvivors had a lower cardiac index than survivors when they first needed FIO2 of 1.0 and ARDS was more frequent among this group. All patients who survived were in severe hypoxemic respiratory failure in the first 5 days post-trauma; all patients who needed FIO2 of 1.0 later than 5 days post-trauma died. Data collected for patients with similar degree of respiratory failure in coronary care ICU (n = 18), in medical ICU (n = 19), and surgical ICU (n = 21) demonstrated that multiple trauma patients with severe hypoxemic respiratory failure were younger and were hospitalized and ventilated for longer periods of time. In multiple trauma patients, as for patients with cardiogenic pulmonary edema, death was seldom related to respiratory failure itself. We concluded that severe hypoxemic respiratory failure in trauma patients is usually of mixed etiologies. It is a serious cause of morbidity in these patients; however, mortality is seldom directly related to this condition. Severe IS occurring shortly after trauma is of better prognosis than late IS.

Adult↗
PubMed1986

Farmer's lung presenting as respiratory failure and homogeneous consolidation.

A 40-year-old woman who worked on a farm and was exposed to moldy hay presented with acute respiratory failure requiring mechanical ventilation and homogeneous radiologic consolidation. Treatment with steroids produced rapid improvement. These features of presentation of hypersensitivity pneumonitis with acute respiratory failure and homogeneous consolidation are rarely encountered.

Adult↗
PubMed1985

[Nocardiosis].

Explore the source record for details and available documents.

Adolescent↗
PubMed1984

Effect of hypoxic hypoxia on systemic vasculature.

Effects of hypoxic hypoxia (HH) on cardiac output (CO), CO distribution, arterial and venous pressure-flow curves, vascular compliance, vascular time constant (tau), and resistance to venous return (RVR) were evaluated on six dogs. The vascular bed was isolated into four compartments depending on venous drainage: superior vena cava (SVC), splanchnic, renal and adrenal, and the remainder of the inferior vena cava (IVC). Low arterial O2 content and PO2 produced a threefold increase in CO at the same mean arterial pressure and a significant redistribution of CO to the SVC. Arterial pressure-flow curves decreased their slope (i.e., flow resistance) by a factor of two in the IVC and renal beds and by a factor of three in the splanchnic and SVC beds. Venous pressure-flow curves for the animal also decreased their slope significantly. HH causes a twofold increase in venous compliance and in mean venous pressure; tau did not change, but RVR halved. Seventy percent of the CO increase is explained by the increase in mean venous pressure and 30% by the reduction in RVR.

Acid-Base Equilibrium↗
PubMed1984

How does positive end-expiratory pressure reduce intrapulmonary shunt in canine pulmonary edema?

We ventilated separately the right and left lungs of seven dogs having thoracotomies and catheters in both lower lobe veins. Two hours after right atrial injection of oleic acid, shunt (Qs/QT) in each lower lobe increased from 0.10 to 0.47. Ten minutes after positive end-expiratory pressure (PEEP) was increased from 3 to 13 cmH2O in one lung, mean lobar Qs/QT decreased to 0.06 with no change in its fraction of pulmonary blood flow measured by microsphere techniques. At the same time mean Qs/QT in the other lower lobe was 0.48. At end expiration each lower lobe hilum was then clamped, and the excised lobe was quickly frozen over liquid N2. There was no difference in the extravascular lung liquid per gram blood-free dry lobe between the lower lobes (7.5 +/- 2.6 ml/g), but perivascular cuff liquid was greater in the lower lobe with PEEP (3.8 +/- 2.8 ml/g) than in the lower lobes without PEEP (2.4 +/- 1.7 ml/g). Light microscopy revealed that 77.8 +/- 9.0% of the alveoli were flooded in the lobe without PEEP, but only 22.2 +/- 11.8% were flooded in the lobe with PEEP. The mean linear intercepts of the flooded alveoli were not different between lower lobes, and both were reduced to about 50% of the size of adjacent unflooded units in the same lobe. Alveolar septum thickness was greater without PEEP. We conclude that PEEP reduces Qs/QT by inflating previously flooded and collapsed air spaces and by redistributing the excess alveolar water into the compliant perivascular space, thus eliminating the obstacle to pulmonary O2 transfer.

Animals↗