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Biomedical subjects

P Robert

Publications and source records attributed to P Robert.

At least 91 records · Page 5Linked to original sources
PubMed1985

A magnetic device to stimulate selected whiskers of freely moving or restrained small rodents: its application in a deoxyglucose study.

After receiving an intraperitoneal injection of [14C]2-deoxy-D-glucose (2-DG), a total of 28 mice which had pieces of metal wire glued to certain whiskers (all others were clipped) were exposed to magnetic field bursts. The stimulated whiskers were B1 (freely moving mice, set I) or whiskers C1-3 and E1 (restrained mice, set II) on the left side. In set I, stimulated mice were compared with animals of various control groups. Autoradiography demonstrated an activation of columnar shape overlying the presumed corresponding barrel contralateral to stimulation; in a part of the ipsilateral barrelfield, 2-DG uptake was depressed significantly. In the subnuclei caudalis and interpolaris of the trigeminal brainstem complex a spot of activation was observed ipsilaterally but there was no depression contralaterally. Whereas several animals of the control groups showed some aspects of these responses, they were consistent only in stimulated mice. In set II, animals received stimulation with different intensities. 2-DG uptake was higher in barrels C1-3 than in E1. It increased with increasing intensity. The same observations were made in two nuclei of termination. The device we describe here can be used to study stimulus-specific responses at various levels of the somatosensory pathway.

Animals↗
PubMed1985

A logistic regression analysis of multiple noninvasive tests for the prediction of the presence and extent of coronary artery disease in men.

The incremental diagnostic yield of clinical data, exercise ECG, stress thallium scintigraphy, and cardiac fluoroscopy to predict coronary and multivessel disease was assessed in 171 symptomatic men by means of multiple logistic regression analyses. When clinical variables alone were analyzed, chest pain type and age were predictive of coronary disease, whereas chest pain type, age, a family history of premature coronary disease before age 55 years, and abnormal ST-T wave changes on the rest ECG were predictive of multivessel disease. The percentage of patients correctly classified by cardiac fluoroscopy (presence or absence of coronary artery calcification), exercise ECG, and thallium scintigraphy was 9%, 25%, and 50%, respectively, greater than for clinical variables, when the presence or absence of coronary disease was the outcome, and 13%, 25%, and 29%, respectively, when multivessel disease was studied; 5% of patients were misclassified. When the 37 clinical and noninvasive test variables were analyzed jointly, the most significant variable predictive of coronary disease was an abnormal thallium scan and for multivessel disease, the amount of exercise performed. The data from this study provide a quantitative model and confirm previous reports that optimal diagnostic efficacy is obtained when noninvasive tests are ordered sequentially. In symptomatic men, cardiac fluoroscopy is a relatively ineffective test when compared to exercise ECG and thallium scintigraphy.

Adult↗
PubMed1985

[Anesthetic induction with Althesin or diazepam in patients undergoing an aortocoronary bypass].

The haemodynamic effects of induction of anaesthesia with diazepam (group D) and Althesin (group A) were studied in 25 coronary patients under betablockers with good myocardial function. Haemodynamic variables monitored were vascular pressures, cardiac output and systolic time intervals. The effects of both drugs were observed when used alone (time I) and in combination with fentanyl, pancuronium and nitrous oxide (time II). The results seemed to show that Althesin (12.51% fall in SI and 10.79% increase in PEP/LVET) depressed myocardial function more than diazepam (no significant difference), but the introduction of fentanyl, pancuronium and nitrous oxide removed the differences between the drugs as to their effect on myocardial performance. These drugs added a depressant effect to diazepam (13.83% fall in SI and 15.77% increase in PEP/LVET) without increasing Althesin's negative inotropic effect. However, in group A at time II, the pulmonary arterial pressure, the wedge pressure and the pulmonary vascular resistance were significantly reduced, while they remained stable in the diazepam group.

Adrenergic beta-Antagonists↗
PubMed1985

[Circadian rhythms and depression].

The degree to which nature's cycles influence our body is now obvious, owing to the recent progress of chronobiology. It seems thus that the harmonious internal organization of our circadian rhythms depends on the dual influence of the internal clocks as well as the external temporal informations. These endogenous pacemakers, able to spontaneously generate a rhythmicity the period of which is close to 24 hours, could be triggered by environmental informations, such as light/dark or sleep/Wake cycles, on a 24 hours schedule. The disruption of this entrainment could be involved in major affective disorders. This internal or external desynchronisation seems thus to be the central concept of different models for depression. The internal coincidence model suggests that a phase advance of the strong oscillator in reference to the weak oscillator causes depression. An external coincidence model suggests that depression is caused when light/dark cycle or photoperiod provide too little illumination during a critical photosensitive interval which could be located in the second half of the night. At last, a model comparing the biological rhythms of depressed patients and of healthy volunteers during temporal isolation, suggests that the internal clocks of depressed subjects could be temporarily "blind" to environmental time cues involving internal desynchronisation. These emerging findings should open a new therapeutic approach for depression.

Antidepressive Agents, Tricyclic↗
PubMed1984

Clinical and angiographic factors associated with progression of coronary artery disease.

To characterize the clinical and angiographic factors associated with progression of coronary atherosclerosis, 313 consecutive medically treated patients who had had two coronary arteriograms 3 to 119 months (mean 39 +/- 25) apart were studied. One hundred eighty-one patients underwent recatheterization for stable angina, 52 for unstable angina and 80 for various other reasons. In addition to the conventional angiographic features present at the first angiographic study (number of diseased vessels 1.5 +/- 0.8, ejection fraction 59 +/- 11%), an extent score was defined based on the number of coronary segments with 5 to 75% narrowings from a 15 segment coding system. Multivariate logistic regression identified four independent predictors of progression of coronary artery disease: the interval between studies (p less than 0.0001), unstable angina (p less than 0.0001), a high extent score (p = 0.0001) and young age (p = 0.0026). In a subset of 74 patients aged 50 years or younger with, at the time of the first evaluation, an extent score of 4 or more, the probability of progression between 2 and 4 years and after 4 years was, respectively, 80 and 90% compared with 50% for the other patients. Risk stratification for progression of coronary artery disease can thus be obtained.

Adult↗
PubMed1982

Factors predicting working status after aortocoronary bypass surgery.

The working status of 1165 patients aged 59 years or less (mean 49.8 years) was evaluated 7 to 77 months (mean 36 months) after aortocoronary bypass surgery. Although 76% of the patients eventually returned to work, only 56% were working 6 months after their operation. The proportion of patients working peaked at 2 years after the operation (at 66%) and decreased progressively to 56% at 4 years and 53% at 5 years without ever reaching the proportions that applied 12 and 6 months before the operation (84% and 69% respectively). Multivariate analysis identified three socioeconomic and three clinical variables as predicting the working status at 6 months and at yearly points during the first 4 years after the operation. Of the socioeconomic variables analysed, preoperative unemployment of long duration, a preoperative occupation that required strenuous physical effort and a low level of education were, in that order, the strongest predictors of postoperative unemployment. Among the clinical variables, associated noncardiovascular illness and the severity and duration of angina pectoris independently influenced the patients' post-operative working status. The authors conclude that modification of some of these variables should by attempted both before and after aortocoronary bypass surgery to see whether the rate of return to employment after the operation can be improved in selected patients.

Adult↗
PubMed1982

Employment following aortocoronary bypass surgery in young patients.

The work status following aortocoronary bypass surgery was evaluated by questionnaire in 268 male patients aged 44 years or less, after a mean follow-up of 38 months. During follow-up, 87% resumed work; when analyzed on a yearly basis, the rate of patients at work peaked at 2 years (80%) and then declined to 70% at 4 years. Multivariate analyses showed that the two most important preoperative variables predictive of work status after surgery were (1) the length of the period of not working, and (2) the educational level. Other influential factors were the presence of an associated vascular disease and the type of work, annual income and functional class. The postoperative health status, as described by the patient, was also closely correlated with return to work. Recurrence of angina after surgery impaired work resumption. A majority of patients who were never gainfully employed after surgery attributed the reason to their physician, while 93% of them stated that they received financial aid from the government.

Adult↗
PubMed1982

Myocardial protection through cold cardioplegia with potassium or diltiazem. Experimental evidence that diltiazem provides better protection even when coronary flow is impaired by a critical stenosis.

Intermittent aortic root infusion of a cold solution containing either potassium chloride (KCl) or diltiazem was performed in 32 dogs during a 2-hour aortic clamping. Half of the dogs in each group had a critical stenosis created on the circumflex artery before cardiopulmonary bypass. Global left ventricular (LV) function was determined 1 hour after bypass by means of LV pressure, peak dP/dt, LV end-diastolic pressure, cardiac and stroke work indexes. Regional function was assessed through microcrystals in the areas of the circumflex and left anterior descending coronary arteries. LV pressure decreased in all dogs, but more so with the KCl solution (p = 0.02). The stenosis had no specific effect on LV pressure, but affected peak positive dP/dt (p = 0.007) and LV end-diastolic pressure (p less than 0.0001). Cardiac and stroke work indexes decreased more in the KCl group than in the diltiazem group (p less than 0.002) with or without stenosis. Both positive and negative dP/dt were affected by the type of solution (a greater decrease with KCl), but the narrowing affected only the positive dP/dt. Regional LV function remained unchanged in the absence of a narrowing and was depressed equally in dogs with a narrowing whether they received KCl or diltiazem. Overall LV function appeared to be better preserved with diltiazem, with or without impairment of circumflex flow.

Animals↗
PubMed1980

[Changes in work status in a French-Canadian population after aorto-coronary bypass surgery].

Work status after aortocoronary bypass surgery was evaluated in 1 320 male patients who were less than 60 years old at the time of their operation. The percentage of working patients is maximal two years after surgery (66.5 p. 100) and decreases gradually (53 p. 100) at five years. This percentage remains lower than the 84 p. 100 and 69 p. 100 which were observed twelve and six months before the operation. Multivariate analyses showed that the length of the period of pre-operative inactivity had a preponderant role in predicting work status after surgery. The second best predictor was the type of work in patients aged 45 or more and the educational level in younger patients. All other variables-duration of illness, functional class, other illness, postoperative complications, marital status, annual income, age-had a lesser role. Variables predictive of continued employment (greater than or equal to 2 ans) after surgery were similar. Univariate analyses on postoperative factors showed a negative correlation between recurrence of angina and return to work. A majority of patients who never returned to work after surgery kept a stable income (65.5 p. 100) and 83 p. 100 of them received financial aid from the government.

Coronary Artery Bypass↗
PubMed1979

Facilitation reaction (enhancing antibodies and suppressor cells) and rejection reaction (sensitized cells) from the mother to the paternal antigens of the conceptus.

Humoral and cellular immune agents of a maternal reaction were investigated during pregnancy. Fluorescence studies performed on mouse placentae at 14 days detected maternal immunoglobulins of mainly IgG1 but also IgG2 subclasses. These immunoglobulins, after acid elution, can rebind the placenta and the thymocytes of the relevant paternal strain in case of allogeneic pregnancies, demonstrating an antibody activity towards both placenta specific and paternal strain antigens. They can specifically enhance a paternal strain tumour allograft on a maternal strain recipient. Spleen cells from an allogeneically pregnant mother can reduce or promote paternal strain tumour allograft on a maternal strain recipient. The aggressive effect is shown with small doses of transferred cells, whereas large doses promote enhancement. The suppression of the cytotoxic response of the recipient was ascribed to T cells by use of anti-theta plus complement. Thus, both the rejection reaction (immune cytotoxic cells) and the facilitation reaction (enhancing antibodies and suppressor cells) were demonstrated during pregnancy.

Animals↗