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Biomedical subjects

J M Grégoire

Publications and source records attributed to J M Grégoire.

11 recordsLinked to original sources
PubMed2001

Use of thigh pressure cuffs to modulate simulated microgravity-induced changes in the skin measured with high-resolution B-scan ultrasound.

OBJECTIVE: The aim of the present study was to evaluate the fluid shift in a simulated microgravity experiment and to test the use of thigh cuffs to help alleviate the problem. METHODS: The change in skin thickness was assessed by a 20 MHz B-scan ultrasound device. This was performed on eight volunteers who underwent two successive 7-day periods of -6 degrees anti-orthostatic bed-rest, with or without the daytime use of thigh cuffs. The thigh cuffs were used to counteract the development of facial oedema. RESULTS: In the control group (without thigh cuffs), the results showed a steady increase in skin thickness of the combined dermis and hypodermis of the forehead and a reduction of the thickness of this tissue on the tibia. For the countermeasure group, although thigh cuffs were only employed during the daytime - being removed at night - their use reduced the amplitude and kinetics of the fluid shift, resulting in greater beneficial effects at the end of the day than early in the morning. CONCLUSION: These results of objective measurements of skin made using a non-invasive high frequency ultrasonography method confirm reports by cosmonauts of a reduction in facial oedema and a more 'comfortable' adaptation to microgravity by the use of thigh cuffs during space flight. This system is potentially promising for investigating fluid shifts in the skin and may prove useful in the evaluation of some oedematous skin diseases, as well as their therapy.

Adult↗
PubMed1999

T-cell expression of the human GATA-3 gene is regulated by a non-lineage-specific silencer.

The GATA-3 transcription factor is required for development of the T-cell lineage and Th2 cytokine gene expression in CD4 T-cells. We have mapped the DNase-I-hypersensitive (HS) regions of the human GATA-3 gene in T-cells and non-T-cells and studied their transcriptional activities. HS I-III, located 5' from the transcriptional initiation site, were found in hematopoietic and non-hematopoietic cells, whereas HS IV-VII, located 3' from the transcriptional start site, were exclusively observed in T-cells. Among these hypersensitive sites, two transcriptional control elements were found, one in the first intron of the GATA-3 gene and the other between 8.3 and 5.9 kilobases 5' from the GATA-3 transcriptional initiation site. The first intron acted as a strong transcriptional activator in a position-dependent manner and with no cell-type specificity. The upstream regulatory element could confer T-cell specificity to the GATA-3 promoter activity, and analysis of this region revealed a 707-base pair silencer that drastically inhibited GATA-3 promoter activity in non-T-cells. Two CAGGTG E-boxes, located at the 5'- and 3'-ends of the silencer, were necessary for this silencer activity. The 3'-CAGGTG E-box could bind USF proteins, the ubiquitous repressor ZEB, or the basic helix-loop-helix proteins E2A and HEB, and we showed that a competition between ZEB and E2A/HEB proteins is involved in the silencer activity.

Base Sequence↗
PubMed1999

High frequency (20 MHz) ultrasonic devices: advantages and applications.

OBJECTIVE: This paper investigates the problems, advantages and potential applications of 20 MHz ultrasonic devices. METHOD: Aqueous gel and a thin appropriate membrane to enclose the front tip were used with 20 MHz probes without obvious decrease in resolution and sensitivity compared to the results obtained without a membrane and this considerably facilitates their routine use. RESULTS: Many applications with linear scanning were evaluated in dermatology, ophthalmology (investigations of the anterior chamber of the eye, checking of corneal grafts), stomatology (detection and evaluation of periodontal disease) and in the field of measurement of very low velocities in small vessels by means of a duplex probe comprising two 20 MHz transducers: an imaging transducer and an inclined blood flow measurement transducer. Velocity profiles (velocities less than 0.50 mm/s) were measured in 100-300 microm diameter vessels using a cross-correlation method. CONCLUSION: The use of 20 MHz frequency limits resolution but we have shown that this frequency allows the development of easy to handle probes.

Blood Flow Velocity↗
PubMed1996

[Sudden death].

Sudden death accounts for about 7000 deaths per year in Belgium. Everyone could be concerned, from the newborn to the octogenarian. Due to the scientifical and technical progresses of our rescue teams, our hospitals are more often confronted with resuscitated patients. This syndrome must be considered as a whole clinical entity. Its causes, its physiopathological concepts, its diagnostic and prophylactic tools and its treatment should be fully integrated. The actual conceptions are modifying. Those different aspects are reviewed, in the light of the recent literature.

Adult↗
PubMed1996

[In utero measurement of the umbilical cord in full term pregnancy].

OBJECTIVE: The length of the umbilical cord varies widely from one pregnancy to another. Although its average length is 50 cm, this measurement could vary from as little as 20 cm to more than one metre. The purpose of our study was to evaluate, in utero, the length of the umbilical cord during the third trimester of pregnancy knowing the propagation velocity of the pressure wave along the cord. MATERIAL AND METHODS: The computation of the apparent length requires two ultrasound transducers, one situated at the aortic fetal arch, the other at the placental extremity of the umbilical artery. Knowing the velocity of the pressure wave (v), as well as the time interval between the systolic peak of two waves (delta t), we can deduce the length of the umbilical cord (delta t x v). RESULTS: The comparison between the calculated length and the actual length measured shows a significant correlation with a probability of 1%. CONCLUSION: The knowledge of the length of the umbilical cord is quite useful in the physio-pathological interpretation of the placental resistance index. It is also of interest, before the delivery, to know the length of the cord in order to foresee dystocy and how it relates cord which is either too short or too long.

Blood Flow Velocity↗
PubMed1994

Structure and expression of the human GATA3 gene.

GATA3, a member of the GATA family that is abundantly expressed in the T-lymphocyte lineage, is thought to participate in T-cell receptor gene activation through binding to enhancers. To understand GATA3 gene regulation, we cloned the human gene and the 5' end of the mouse GATA3 gene. We show that the human GATA3 gene contains six exons distributed over 17 kb of DNA. The two human GATA3 zinc fingers are encoded by two separate exons highly conserved with those of GATA1, but no other structural homologies between these two genes can be found. The human and mouse GATA3 transcription units start at a major initiation site. The promoter sequence analysis of these two genes revealed that they are embedded within a CpG island and share structural features often found in the promoters of housekeeping genes. Finally, we show that a DNA fragment containing the human GATA3 transcription unit, 3 kb upstream from the initiation site and 4 kb downstream from the polyadenylation site, displays T-cell specificity.

Animals↗
PubMed1990

[Sudden death in athletes].

In France, about one of ten thousand athletes die suddenly each year. Although this is a small proportion of the number of total deaths, it is a striking one because of the subjects it concern e.g: healthy and physically trained. Age is the major determinant cause of sudden death: coronary heart disease in victims over 35 years, hypertrophic cardiomyopathy, congenital disease and aortic rupture before. Positive predictive value of usual tests is given; high value of echocardiography is to be noted, in comparison with low value of the traditional stress test for detection of subjects at risk.

Adult↗
PubMed1989

Diastolic function and modifications of left ventricular architecture in ultraendurance athletes.

Although diastolic function is altered in left ventricular hypertrophy due to aortic stenosis or systemic hypertension, it has been shown to be normal in athletes. To analyze the reason for this discrepancy, we have studied left ventricular masses and volumes and diastolic flow velocities in 13 ultraendurance athletes and in 8 sedentary subjects as a control group by M-mode (TM), two-dimensional (2D) and Doppler echocardiography. Significant differences in the measurements of mass and volume have been found depending upon the method used. Considering that two-dimensional echocardiography is more appropriate for estimations of LV mass and LV volume, especially when the shape of the left ventricle is modified, overestimation of LV mass and underestimation of LV volume in ultraendurance athletes by TM could be explained by an elongation of LV cavity in athletes. Doppler velocimetry showed similar results in athletes and control subjects. We suggest that those LV configurational changes partly explain the preservation of diastolic function in athletes by restoring in diastole the energy stored in systole.

Adult↗
PubMedDate not supplied

[Variability of the RR interval: a measure of systemic sympathetic activity].

Beat-to-Beat variability may now be measured, from 24h ECG recordings (Holter monitoring), in the time domain (by statistical indexes) and in the frequency domain (spectral analysis). This variability gives essential informations about the interactions of different cardiovascular variables, and especially about the balance of the two components of the sympathetic nervous system. It is generally thought that a malfunction of the ortho/parasympathetic balance favours ventricular fibrillation. So the potential interest of this new technique as a predictor of sudden cardiac death seems enormous.

Death, Sudden, Cardiac↗