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Biomedical subjects

M Rey

Publications and source records attributed to M Rey.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Experimental radiosurgery in rats using gamma a "gamma knife". Description of a stereotactic device for small laboratory animals].

To allow the experimental use in rats of a Gamma Knife Radiosurgical Unit, a stereotactic device adapted from the conventional Kopf's device was developed. To control the accuracy of the coordinate system based on the De Groot's rat stereotactic atlas, experimental radiosurgical lesions were made on the left striatum. The isodose curve distribution of the 4 mm collimator was calculated with the dose planning software used in Gamma Knife and superimposed on the left striatum target. Doses of 200 Gy were administered to the left striatum in six rats. The results were evaluated 21, 34 and 47 days later. At 34 and 47 days necrotic lesions were exactly as targeted. In a second group of 48 rats receiving a doses of 100 Gy, no lesions were observed after 7, 15, 24, 31, 45 days. However, in all rats sacrificed 59, 72 and 90 days after day radiation, a necrotic lesion was always present and confirmed that at each time the lesions were precisely targeted. This apparatus allows precise and reproducible gamma irradiation lesion in rat brain without expensive and time consuming imaging techniques. This device provides a useful system to observe the experimental effects of radiosurgery on the central nervous system in rats.

Animals↗
PubMed1995

Mutism and auditory agnosia due to bilateral insular damage--role of the insula in human communication.

We report a case of transient mutism and persistent auditory agnosia due to two successive ischemic infarcts mainly involving the insular cortex on both hemispheres. During the 'mutic' period, which lasted about 1 month, the patient did not respond to any auditory stimuli and made no effort to communicate. On follow-up examinations, language competences had re-appeared almost intact, but a massive auditory agnosia for non-verbal sounds was observed. From close inspection of lesion site, as determined with brain resonance imaging, and from a study of auditory evoked potentials, it is concluded that bilateral insular damage was crucial to both expressive and receptive components of the syndrome. The role of the insula in verbal and non-verbal communication is discussed in the light of anatomical descriptions of the pattern of connectivity of the insular cortex.

Adult↗
PubMed1995

First selective amygdalohippocampal radiosurgery for 'mesial temporal lobe epilepsy'.

All the well-documented radiosurgery of epilepsy cases are secondary epilepsies with space-occupying lesions. These results have prompted the idea of testing radiosurgery as a new way of treating epilepsy without space-occupying lesions. We have treated 4 patients with 'mesial temporal lobe epilepsy'. The preoperative evaluation programme was one we usually perform for patients selected for microsurgery of epilepsy. We report the baselines of this treatment, the radiosurgical protocol details, and preliminary results for the first patient treated (follow-up 16 months). Since treatment, the patient has been seizure free, but it is too soon to draw long-term conclusions about the efficiency of the radiosurgery of epilepsy. Morphological (MRI) and functional (PET scan) changes are discussed in relation to our technical choices. Our amygdaloentorhinohippocampal target has been selectively injured.

Adult↗
PubMed1995

[The reversibility of pulmonary hypertension associated with autoimmune hyperthyroidism].

We report the case of a 28-year-old woman in a chronic hemodialysis program, who developed moderate pulmonary hypertension (eco-Doppler assumed pulmonary systolic pressure of 62 mmHg), with right ventricular dilatation (49 mm) in coincidence with a fully symptomatic autoimmune hyperthyroidism. The improvement of thyroid function resulted in a significant regression of pulmonary hypertension (45 mmHg) and normalization of right ventricular size (35 mm). The appearance and reversibility of pulmonary hypertension associated to autoimmune hyperthyroidism have not been described before and, in our patient, it is probably facilitated by other coincident factors that increase cardiac output and, subsequently, pulmonary flow, i.e. anemia and the arteriovenous fístula for hemodialysis.

Adult↗
PubMed1994

Protective effect of ethanol on X-ray-induced mitotic recombination in Drosophila melanogaster.

The effect of ethanol pretreatment on X-ray-induced mitotic recombination in D. melanogaster females was investigated by means of the white/white+ (w/w+) spot test. White females inseminated by yellow males were allowed to oviposit for 8 hr on medium containing 5%, 7.5% and 10% (v/v) ethanol and submitted to 10 Gy of X-rays 52 hr after the beginning of the egg laying period (chronic treatments). For acute treatments 56 +/- 4-hr-old larvae grown in regular medium were held in petri dishes containing filter paper soaked with 50% (v/v) ethanol for 30 min before being irradiated with 10 Gy. The emerging heterozygous w/w+ females were inspected for the presence of white spots (LS) in their eyes. Acute ethanol pretreatments lead to a significant reduction in the frequency of LS. This is suggested to be due to the scavenging by ethanol of free radicals originating during irradiation. If so, the contribution of the indirect action of radiation to mitotic recombination induced by X-rays must be significant. Chronic ethanol pretreatments also resulted in a decrease of LS, though impairment of larval development by ethanol may have partly contributed to the effect observed. At the concentrations tested, ethanol by itself did not modify the frequency of LS observed in the control.

Animals↗
PubMed1994

Lack of effect of acute acetaldehyde treatment on X chromosome segregation in Drosophila melanogaster females.

The effect of acute acetaldehyde treatments on X chromosome segregation was tested in germinal cells of Drosophila melanogaster females. The experiments were carried out using a test system where the nondisjunctional females (XXY) and only 1/4 of the expected regular progeny are viable. 24 h old virgin females were exposed for 60 min to 3, 4 and 5% acetaldehyde solutions by means of soaked tissue paper placed at the bottom of regular culture vials. After mating the females were brooded daily. Two additional experiments were performed with 0-2 h old and 4-5 day old virgin females using a 4% acetaldehyde solution. The results obtained show that acetaldehyde did not affect X chromosomal segregation in oocytes. This lack of effect could result from the highly efficient ADH-ALDH dependent detoxifying mechanism operating in Drosophila melanogaster.

Acetaldehyde↗
PubMed1994

Assessment of chronic tricuspid regurgitation by colour Doppler echocardiography: a comparison with angiography in the catheterization room.

Colour Doppler echocardiographic (CDE) assessment of tricuspid regurgitation (TR) has been limited by the lack of an accepted model against which it can be compared. Angiography is said to be inadequate because catheter placement across the tricuspid valve could induce artifactual TR. Thirty-five consecutive patients with left-sided valvulopathy and recent heart failure were studied. Angiography was validated by CDE, which demonstrated that catheter placement across the tricuspid valve did not increase the size of the regurgitant jet in the first 30 cases. All the patients were studied with CDE immediately before performing the angiography in order to compare the findings of both techniques. From all the CDE parameters measured among the angiographic groups, the jet area overlapped the least (P = 0.024). The diameters of the right cardiac chambers were larger in angiographically severe cases (P = < 0.003 to 0.041), and a scale of severity that combined jet area and right atrium area showed an excellent correlation with angiography (r = 0.924; P < 0.001). Furthermore, maximal instant systolic gradients between the right cavities, estimated by catheterization, were lower in severe cases (P = 0.038). Assessment of these gradients by continuous Doppler can enhance recognition of severe TR. The analysis of jet area, right atrium area and regurgitant gradient by CDE can provide excellent assessment of TR.

Adult↗
PubMed1994

Endogenous polyamine concentrations in juvenile, adult and in vitro reinvigorated hazel.

We investigated endogenous polyamine concentrations in leaves from juvenile and mature hazel (Corylus avellana L.) shoots, as well as leaves from shoots obtained by both forced outgrowth and micropropagation of adult tissues. To determine if the observed in vitro reinvigoration was associated with polyamine metabolism, we tested the effect of serial subcultures on polyamine concentrations. Polyamines, mostly free putrescine, were higher in juvenile tissues. Adult tissues micropropagated for 14 subcultures had polyamine concentrations characteristic of juvenile tissues. However, with additional subcultures, total polyamine concentrations decreased. The putrescine to spermidine plus spermine ratio was higher in juvenile and micropropagated tissues than in adult tissues, but decreased in micropropagated tissues after 20 subcultures. This ratio may reflect a balance between vegetative growth and reproductive processes. Thus, an analysis of polyamine concentrations may provide a simple assay for determining the juvenility of plant tissues and, hence, their suitability for micropropagation.

Journal Article↗
PubMed1994

Corticosterone effects on long-term potentiation in mouse hippocampal slices.

Corticosterone (CORT) can alter several electrophysiological properties in the hippocampus. Few studies have reported the effects of CORT on hippocampal long-term potentiation (LTP). In the CA1 region of the hippocampal slice, we studied the relative increase in population spike (PS) amplitude after inducing tetanus (PS-LTP) in control conditions and in the presence of CORT (0.5 nM or 5 microM). Two perifusion mediums were used which differed in calcium concentration (M1:Ca 2.5 mM; M2: Ca 3.1 mM). In the control slices, the PS-LTP amplitude was greater in the M1 medium. With the low CORT concentration (0.5 nM), the PS-LTP amplitude was greater than in control conditions in the M2 medium only. A similar PS-LTP amplitude increase was also observed in the M2 medium after application of 0.5 nM aldosterone (type I receptor analog). With the high CORT concentration (5 microM), PS-LTP amplitude decreased in the two conditions. This effect was reversed by co-application of RU486 (type II receptor antagonist). These results demonstrate that CORT can modulate PS-LTP via its two types of hippocampal CORT receptors, depending on the concentration applied. They also showed that the extracellular calcium concentration may contribute to the functional change induced by CORT.

Aldosterone↗
PubMed1994

Relation between polysomnographic parameters and apnea index in obstructive sleep apnea syndrome.

We performed overnight polysomnography in 77 patients for diagnosis of sleep apnea syndrome (SAS) and assessment of severity. Patients were classified into 3 groups according to apnea index (AI): group 1 (G1; no SAS), AI < or = 10 (21 patients), group 2 (G2; moderate SAS), 10 < AI < 40 (34 patients), and group 3 (G3; severe SAS), AI > or = 40 (22 patients). In all 3 groups, 60% of the apneas were obstructive, but the proportion of mixed apnea increased from G1 to G3 (6% in G1, 12% in G2, and 24% in G3). The duration of REM sleep was shorter in G2 and G3 than in G1 (G1 61 min, G2 44 min, G3 41 min; p < 0.03). In G3 a dramatic decrease in deep sleep was noted in comparison with G1 and G2 (G1 29 min, G2 31 min, G3 10 min). The distribution of the apnea in the different sleep stages was similar in G3; in G2, 16 patients had a REM apnea predominance, but in this subgroup duration of REM sleep was longer and AI was lower than in the other 18 G2 patients. So, absence of sleep stage apnea predominance and high proportion of mixed apnea were observed in the most severe SAS.

Carbon Dioxide↗
PubMed1994

Surfactant bolus instillation: effects of different doses on blood pressure and cerebral blood flow velocities.

Fifteen preterm infants suffering from respiratory distress syndrome were randomly allocated to receive either high-dose (200 mg/kg) or low-dose (100 mg/kg) surfactant treatment. Retreatments were done with the low dose. Blood pressure, blood gases and cerebral blood flow velocities were determined before and after 24 bolus instillations. With the high dose mean blood pressure and mean cerebral blood flow velocity dropped significantly. With the low dose only mean cerebral blood flow velocity decreased; the course was unrelated to blood pressure or PCO2 fluctuations. The mechanisms leading to the observed circulatory changes after surfactant instillation remain unclear.

Blood Flow Velocity↗
PubMed1994

Differences in morbidity and mortality according to type of referral of very low birthweight infants.

Maternal and social risk, prenatal and obstetric care, resuscitation and neonatal care in very-low-birthweight infants (VLBW) may vary with the type of referral. In 453 VLBW's (< 1500 g) admitted to our neonatal intensive care unit 1987-1992, we classified transport type as: A: No transport (n = 240), B: Maternal transport (n = 88), C: Infant transport (n = 125). Stepwise multiple discriminant function was determined for the identified factors. The risk of mortality was investigated by logistic regression analysis. In group A, mean maternal age was higher and mothers' social status lower than in groups B and C. In group B, infants were considerably smaller and less mature, but when adjusted for gestational age, suffered less frequently from RDS, obviously due to more frequent induction of lung maturation. In group C, less than half of the infants were resuscitated by a neonatologist. Infants of this group were frequently hypothermic at admission and required prolonged artificial ventilation more frequently. Total VLBW survival averaged 77%, increasing from 69 to 88% within the study period. Total rate of severe intraventricular hemorrhage was 4.8% in surviving infants. VLBW infants with different forms of referral differ in their inherent risk. After maternal transport they have less morbidity despite a higher grade of immaturity. Regionalization of perinatal care for these infants remains the greatest potential for further reduction in infant mortality.

Female↗
PubMed1993

End-tidal CO2 analysis in sleep apnea syndrome. Conditions for use.

The diagnosis of sleep apnea syndrome (SAS) requires expensive and complex instrumentation. The purpose of the present study was to determine the value of end-tidal CO2 (EtCO2) in screening for sleep apneas. Thirty-nine patients referred to our sleep laboratory because of suspected SAS and ten normal subjects were studied. The EtCO2 was measured using an infrared spectrometer (POET) designed for simultaneous measurement of CO2 and pulse oximetry. In 29 subjects, expired gas was sampled with a nasobuccal mask (Respiron) with lateral orifices. In the other 20 subjects, sampling was done with nasobuccal prongs (Criticare) comprising a four-channel plastic tube to the mouth and the nostrils. Data from an 8-h night were transferred the following day to a microcomputer (Apple Macintosh) for processing. Apnea was defined as an absence of detection of CO2 for more than 10 s. Conventional polysomnography was performed (Respisomnographe). The number of apneas in 8 h and the apnea index (number of apneas in 1 h) were calculated after visual analysis on the screen of the polysomnograph and also with EtCO2 analysis. For recordings made with a nasobuccal mask, the regression curve between the apnea indices computed with EtCO2 and polysomnography was an order 2 polynomial curve (r = 0.76; p < 0.001), with an inflection point at 39 apneas per hour. For recordings with nasobuccal prongs, the correlation was very significant (r = 0.95; p < 0.0001), and the regression curve was linear. The EtCO2 with nasobuccal prongs appears to be a simple and reliable method for screening for SAS.

Adult↗