Biomedical subjects

R Picard

Publications and source records attributed to R Picard.

At least 19 recordsLinked to original sources

PubMed2000

Coupling between agonist and chloride ionophore sites of the GABA(A) receptor: agonist/antagonist efficacy of 4-PIOL.

Eight gamma-aminobutyric acid (GABA) mimetics were tested on their ability to differentiate native GABA(A) receptor subtypes present in various rat brain regions. In rat brain cryostat sections, little regional variations by the agonistic actions of muscimol, thiomuscimol, 4,5,6,7-tetrahydroisoazolo(5,4-c)pyridin-3-ol, piperidine-4-sulphonic acid, taurine and beta-alanine on [35S]t-butylbicyclophosphorothionate ([35S]TBPS) binding to GABA(A) receptor channels were found. They were very similar to those found for GABA itself and indicated no direct correlation with single subunit distributions for any of these compounds. Only the low-efficacy GABA mimetic 5-(4-piperidyl)isoxazol-3-ol (4-PIOL) acted like a weak partial agonist or antagonist depending on the brain area. As the cerebellar granule cell layer was relatively insensitive to both modes of action, we tested 4-PIOL in recombinant alpha1beta2gamma2 (widespread major subtype) and alpha6beta2gamma2 (cerebellar granule cell restricted) receptors where it had different effects on GABA-modulated [35S]TBPS binding and on electrophysiological responses. 4-PIOL may thus serve as a potential lead for receptor subtype selective compounds.

Animals↗

PubMed1999

Quantifying driver stress: developing a system for collecting and processing bio-metric signals in natural situations.

A system for quantifying the physiological features of emotional stress is being developed for use during a driving task. Two prototypes, using sensors that measure the driver's skin conductance, respiration, muscle activity, and heart activity are presented. The first system allows sampling rates of 200 Hz on two fast channels and 20 Hz on six additional channels. It uses a wearable computer to do real-time processing on the signals and has an attached digital camera which was used to capture images of the driver's facial expression once every minute. The second system uses a car-based computer that allows a sampling rate of 1984 samples per second on eight channels. This system uses multiple video cameras to continuously capture the driver's facial expression and road conditions. The data is then synchronized with the physiological signals using a video quad-splitter. The methods for extracting physiological features in the driving environment are discussed, including measurement of the skin conductance orienting response, muscle activity, pulse, and respiration patterns. Preliminary studies show how using multiple modalities of sensors can help discriminate reactions to driving events and how individual's response to similar driving conditions can vary from day to day.

Automobile Driving↗

PubMed1994

Birth weight discordance, intrauterine growth retardation and perinatal outcomes in twins.

In a population-based study, the association between twin perinatal outcome, birth weight discordance and intrauterine growth retardation (IUGR) was investigated. Mortality was examined in 1,145 twin pairs, and neonatal morbidity was studied in 315 live-born pairs. In this study, birth weight discordance was defined as > or = 25% of the weight of the heavier twin, and IUGR was defined as < 10th percentile of gender- and gestational age-specific singleton birth weight. In univariate analyses IUGR and discordance were associated with mortality but not with morbidity. When twins were categorized by discordance and IUGR simultaneously, stillbirths were associated with IUGR, while discordant twins had elevated risks of early neonatal death. In multiple logistic regression analyses, which also included gestational age, mode of delivery, birth order, birth weight discordance and IUGR, low birth weight was the single consistent factor associated with elevated risks of mortality and morbidity. For every 250-g increase in birth weight, the risks for each condition examined fell by about 40%. Discordance was an independent risk factor only for hypoglycemia, while IUGR was not associated with any neonatal outcome. Birth weight itself seems to be the most important factor associated with perinatal outcome in twin births. Therefore, the weight of the individual fetus should be the focus of concern of the medical profession in the effort to reduce adverse outcomes in twin pregnancies.

Analysis of Variance↗

PubMed1991

Factors associated with neonatal problems in twin gestations.

We examined the neonatal outcome of 644 twins weighing 500 g or more and 656 singletons, born in the years 1984-1986 in the Soroka Medical Center, Beer-Sheva, Israel. There was nearly a four-fold risk of antepartum death in twins vs singletons, which disappeared when birth weight was controlled for. The risks for intrapartum and early neonatal mortality were not raised in this population. A statistically significant relative risk for congenital heart malformations in twins vs singletons remained (RR = 5.0, 95% CI = 1.5-16.3), after controlling for maternal age. Significantly higher rates of hyalin membrane disease, hypoglycemia, hyperbilirubinemia, anemia and septicemia were found in twins. Controlling for the confounding of the association between twinning and mortality or morbidity caused by differences in distributions of mode of delivery or gestational age between twins and singletons, was not as efficient as the controlling for birth weight. Thus, adjustment for birth weight removed all the excess risks detected except in hypoglycemia. Our findings suggest that the lower birth weight of twins, which is so intimately associated with multiple gestations, is probably the single most important factor associated with neonatal problems found in twin births.

Adult↗

PubMed1991

Ethnicity and sex ratio in twin births.

The patterns of sex ratio in Israeli twins by maternal age and parity are described in two ethnic subpopulation. Jews and Bedouins differ one from the other in genetic, environmental, lifestyle, and reproductive factors. In the Jewish subpopulation, the proportion of males was significantly lower in twin than in singleton births; parity increased the odds of male twin births while maternal age had the inverse effect. In the Bedouin subpopulation, the sex ratio did not differ significantly from that of singletons, and no consistent patterns were found by maternal age and parity. The data suggest that several factors may influence the sex ratio in twin births. In Jewish twin births, the findings are consistent with the literature and can be largely explained in terms of high level of maternal gonadotropins. In the Bedouin subpopulation, paternal influence which could be related to lifestyle may be present, and as yet undefined genetic factors may also be involved. It would be of great interest, therefore, to continue monitoring of the effects of changes in lifestyle on the Bedouin population in order to tease out the relative importance of the varying factors on the sex ratio of twin births.

Adult↗

PubMed1990

[Congenital mitral and tricuspid double stenosis].

The authors report the case of a child followed up from the age of 4 months to the age of 15 for asymptomatic congenital heart disease. Initial clinical examination showed the presence of a systolic murmur and a diastolic rumble in the xiphoid area with signs of right atrial dilatation-hypertrophy. During follow-up, an apical diastolic rumble was detected with left atrial dilatation from the age of 3. Doppler echocardiography carried out recently showed double mitral and tricuspid valve stenosis with two-dimensional appearances of doming of both valves and moderate transvalvular pressure gradients with slight elevation of pulmonary artery pressures on the Doppler study. The very early detection of the malformation and the continuous follow-up of this patient indicate the congenital and not rheumatic origin of this double valve stenosis.

Adolescent↗

PubMed1990

Twinning in southern Israel. Seasonal variation and effects of ethnicity, maternal age and parity.

Seasonality of births in southern Israel was examined in two populations, Jews and Bedouins, with distinctly different life-styles. The study included 1,444 twin births that occurred between the years 1970 and 1986. The peak month for the birth of monozygotic twins was September in both populations, while the maximum number of deliveries occurred in January for the Bedouins and August for the Jews. Of Jewish dizygotic twin births, higher rates were found from July to December. In addition, the peak months of singleton births in women aged 35 years and older and in women of high parity did not coincide with the peak months of multiple births. Maternal age and parity have been shown to greatly influence twin birth rates. The autumnal peak we found, which was independent of ethnic origin and its associated cultural and sociologic differences, was also independent of maternal age and parity and was consistent with findings in other populations in the northern hemisphere. That finding suggests that a seasonal factor, as yet undefined, affects the rates of multiple births.

Ethnicity↗

PubMed1989

Twinning in southern Israel; secular trends, ethnic variation and effects of maternal age and parity.

Twin births in southern Israel between 1970 and 1986 were examined in the Jewish and Bedouin populations. An increase in dizygotic twinning in the whole population, largely due to an increase of rate in the Bedouin population was found. The dizygotic twinning rate in the Bedouin population rose until it reached the level found in the Jewish population. No change with time was found in the monozygotic twinning rates in either population. This suggests that while dizygotic twinning rates are influenced by environmental factors, the monozygotic twinning rates are not. The effects of maternal age and parity on dizygotic and monozygotic twinning rates differed in the two ethnic groups examined. In the Jewish population the dizygotic twinning rate was related to maternal age and parity, while in the Bedouins only maternal age affects the rate. The monozygotic twinning rate has an inverted U shape with maternal age in the Jewish population and is linearly related to maternal age in Bedouin women. No effect of parity on the Jewish monozygotic twinning rate is found but this rate is directly affected by parity in Bedouin women. The effects of maternal age and parity together were examined in both populations. Both maternal age and parity affected the twinning rates; however, the effects are not additive and no interaction between maternal age and parity was found.

Adult↗

PubMed1989

[Measurement by isotope study of the cardiac output in the elderly].

Cardiac output and haemodynamic volumetric values (stroke volume, stroke index, left ventricular end-diastolic volume, blood volume, mean corpuscular volume and packed red cell volume) were measured in a population of 69 very old subjects (80 to 102 years) whose heart was regarded as normal on the basis of criteria determined, by radiocardiography and radionuclide ventriculography. These harmless and non-invasive techniques provided reference values in subjects of a seldom explored age group. Altogether, these values were lower than those of younger adults, and they decreased with age. Their reliability is due to the fact that they were obtained by true measurement and not by extrapolation of results observed in adults.

Age Factors↗

PubMed1989

Uterine rupture complicating midtrimester abortion. A report of two cases.

Uterine rupture occurring during a midtrimester abortion is rare. This complication may lead to profound shock and death as well as to interference with the patient's future fertility. Two patients sustained a uterine rupture during midtrimester abortion. This complication seems to be preventable. The risk of uterine rupture due to overstimulation is higher when amnioinfusion with prostaglandin or hypertonic saline is combined with the use of other oxytocic drugs. Grand multiparas undergoing amnioinfusion should not be given oxytocin; in the rare cases in which oxytocin is needed, it should be administered cautiously and monitored continuously. When a supplemental agent, such as an oxytocic, is needed, it should not be started until several hours after the amnioinfusion.

Abortion, Therapeutic↗

PubMed1987

[Incomplete spontaneous rupture of the supravalvular aorta complicated by pericarditis and aortic insufficiency].

The natural history of an incomplete spontaneous rupture of the ascending aorta over a 4-year period is reported. The initial presentation was subacute pericarditis which regressed spontaneously. Aortic regurgitation developed on the 100th day of the disease and was perfectly well tolerated haemodynamically for 4 years. This favourable course was interrupted by type I aortic dissection. The post-mortem examination provided an explanation for the peculiar development and course of the aortic regurgitation: it was due not to the usual prolapse of the cups but to displacement of the left posterior commissure by the retractile fibrosis arising from the lower lip of the spontaneous rupture.

Aged↗

PubMed1986

[Restoration of fertility following excision of an intracranial hydatid cyst].

An unusual case of a 31 year-old Bedouin women, with secondary infertility of 13 years' duration who conceived twice spontaneously after removal of a hydatic cyst from her frontal lobe is reported. The reproductive function was restored probably by releasing the hypothalamic-pituitary axis from the pressure exerted by the cyst.

Adult↗

PubMed1986

[Intrauterine death of one of the fetuses in a twin pregnancy].

A case of twin pregnancy complicated by intra-uterine death of one fetus 10 weeks before term is described. The occurrence of this complication raises difficult questions about the management and outcome of this rare event. A review of 23 patients with similar findings brought us to the conclusion that the management protocol to be applied should be based, if possible, on the type of placentation.

Adult↗

PubMed1985

[Necrotizing fasciitis following abdominal hysterectomy].

Necrotizing fasciitis is a rare disease with a high mortality and morbidity rate. The authors report the case of a 52 year old woman with necrotizing fasciitis following abdominal hysterectomy. The early diagnosis and the radical surgery saved her life from this serious type of infection. By describing this case, the authors wish to emphasize their opinion that early diagnosis is essential to survival and the most important aspect of management is early aggressive surgical intervention.

Fasciitis↗

PubMed1984

[Pericarditis and pulmonary embolism. A difficult differential diagnosis and a confusing association].

The association of pericarditis and pulmonary embolism may be the source of diagnostic error and delay in the administration of anticoagulant therapy. Two cases are reported. Pericarditis occurred late in patients with severe, chronic pulmonary embolism with electrocardiographic changes of acute cor pulmonale. Two physiopathological mechanisms for this association have been proposed. The first, haemodynamic, suggests friction between the pericardium and distended right ventricle and pulmonary artery. The second, an immunological hypothesis, compares the association of pericarditis and pulmonary embolism to that of the Dressler syndrome after myocardial infarction. This assimilation would imply the constitution of an anatomical pulmonary infarction. It is not justifiable to accept this pathogenesis on the evidence of transient pulmonary opacities resulting from intra-alveolar haemorrhage or of linear opacities of pulmonary atelectasis secondary to hypocapnic pneumoconstriction which are radiological signs of anatomo-physiological stages of pre-infarction.

Aged↗

PubMed1982

[Cryptic miliary tuberculosis. Two case-reports (author's transl)].

The term cryptic miliary tuberculosis designates a particular form of hematogenous tuberculosis in which the usual diagnostic criteria, especially the roentgenographic ones, are lacking. Two cases are reported. Initial clinical manifestations were prolonged fever, poor general condition, low blood pressure, low serum sodium, mild hepatic biological disorders, and myocarditis. No other radiological or biological features, suggestive of tuberculosis were found. In the first patient, the various visceral tuberculous localizations occurred under specific treatment, although the latter was otherwise effective. In the second patient, they were identified by pathological examination. The incidence of these occult forms of tuberculosis, where diagnosis is often established too late, and sometimes only postmortem, is not negligible. This possibility must be borne in mind in severe infectious conditions without obvious etiology, particularly when the following features are present : inadequate secretion of ADH, which often indicates latent encephalitic and meningitic involvement where CSF anomalies may be incomplete or lacking ; leucopenia or pancytopenia ; biological hepatic anomalies ; exceptionally, such as in the two cases described, cardiac involvement. Among diagnostic procedures, liver biopsy is of the utmost importance. Mere diagnostic presumption is sufficient to warrant initiation of antituberculous therapy. This ensures survival and, paradoxically, allows delayed overt clinical manifestations to develop.

Acute Disease↗

PubMed1981

[Cerebrovascular accident presenting as continuous partial epilepsy (author's transl)].

Epileptic seizures due to cerebrovascular accidents are relative rare and only very exceptionally occur in the form of Kojewnikoff's continuous partial epilepsy. A 75-year-old man developed myoclonic spasms, limited to the face, following a left posterior cerebral ischaemic accident. The authors discuss the relationship between epilepsy and cerebrovascular accidents, and differentiate post-ischaemic epilepsy of deferred onset from epilepsy occurring simultaneously with a vascular accident, the latter sometimes presenting as fits. The relationship between myoclonic spasms and Kojewnikoff's continuous partial epilepsy are also discussed.

Aged↗

PubMed1980

In vitro performance assessment of tubular membrane oxygenators.

The definite advantage in oxygen transfer performance of staged (single, double and triple) tubular membrane oxygenators (TMO) is compared with reference to flat membrane oxygenators (Travenol or Landé Edwards). The overall construction of staged TMO with a blood mixing chamber is a very good way to destroy the blood boundary layer and modify the blood stagnant zone in the device. Four sizes of staged TMO were studied using the principle that gases dissolve in water in concentrations linearly proportional to the partial pressures of the gases when in equilibrium with the liquid. The experimental results show that the oxygen transfer rate and the corresponding overall oxygen mass transfer coefficient of staged TMO are increased by the same order as those of the reference membrane oxygenators. Furthermore the essential parameter analysis prove that oxygen transfer increases with the number of stages and decreases with the length of the blood tubular modules. The multistage design of TMO revealed an increase in the hydrodynamic resistance occurring in the apparatus. However the highest relative oxygen transfer efficiency suggests that better fluid distribution as well as better uniformity of oxygenation prevail in the staged devices.

Evaluation Studies as Topic↗