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Biomedical subjects

M Bellet

Publications and source records attributed to M Bellet.

At least 73 records · Page 4Linked to original sources

Central hypotensive effect of diprenorphine in normotensive rat and SHR.

Opioid compounds injected intracisternally in rats induce a centrally-mediated increase in blood pressure. In the present study, the intracisternal injection of an antagonist of opioid compounds, diprenorphine was examined. Diprenorphine caused a similar blood pressure decrease in spontaneously hypertensive rats and normotensive control Wistar Kyoto rats both in young and adult animals. This represents an important argument concerning a role of endogenous opioids in blood pressure control in anaesthetized rats but suggests that brain stem endogenous opioids may not be involved in the mechanism of hypertension.

Animals↗

[Endorphins: neuromodulators and hormones (author's transl)].

The discovery of opiate receptors has resulted in the isolation of endogenous morphinomimetics called endorphins. The enkephalins, which are pentapeptides, are located diffusely within the brain and are thought to act locally as neuromodulators for the release of noradrenaline, dopamine and substance P. beta-endorphin, a peptide with 31 aminoacids, is released from the pituitary with ACTH during stress. The peptide sequency of the common precursor of these hormones, pro-opiocortin, is now established.

Brain↗

[Annular pancreas in the adult (author's transl)].

Annular pancreas--a congenital malformation consisting of a ring of pancreatic tissue around the second part of the duodenum--is a rare surgical condition in adults. It may be responsible for occlusion in the newborn, but frequently remains latent or does not reveal itself until adulthood, usually around the age of 40. The only symptoms are ulcer-like epigastric pains; vomiting occurs at a late stage and jaundice irregularly. Hypotonic duodenography shows, at best, duodenal stenosis, the extrinsic origin of which is disclosed by fiberoscopy. Pre-operative investigations should aim at detecting a gastro-duodenal ulcer or an associated chronic pancreatitis. Owing to the presence of an excretory duct within the ring, section of the latter entails a risk of fistulisation. The best prospects of cure are offered by digestive tract derivation procedures: latero-lateral duodeno-duodenostomy, gastro-enterostomy and duodeno-jejunostomy on a Y-shaped excluded jejunal loop.

Adult↗

Central cardiovascular effects of narcotic analgesics and enkephalins in rats.

1. The cardiovascular effects of morphine, fentanyl, [D-Ala2]-met-enkephalinamide were analyzed after intracisternal injection in anaesthetized rats. PaO2 was measured as an index of respiratory function. 2. At low doses in spontaneously breathing rats, morphine, fentanyl and [D-Ala2]-met-enkephalinamide induced a pressor response with slight tachycardia and no significant change in PaO2. 3. The pressor response appeared to be due to activation of opiate receptors and mediated through the sympathetic nervous system. 4. High doses of morphine and [D-Ala2]-met-enkephalinamide induced a biphasic effect with a secondary hypotension associated with bradycardia in spontaneously breathing rats. A marked reduction in PaO2 was found during the depressor phase. 5. High doses of [D-Ala2]-met-enkephalinamide produced only a pressor response in artificially-ventilated rats with no signs of secondary hypotension. 6. Our data support the idea that morphinomimetic agents are centrally pressor at low doses in the rat. The respiratory depression observed with high doses may be the cause of hypotension.

Analgesics, Opioid↗

[Possibilities and limits of angiographic exploration of the deep femoral artery using posteroanterior projections as described by Dos Santos. Radiological and therapeutic consequences (author's transl)].

The study concerns 36 patients treated by an aortobifemoral shunt operation. The decision to operate followed conventional posteroanterior arteriography using the technique described by Dos Santos. Surgical exploration of 54 deep femoral arteries (DF) was conducted during the approach to the femoral tripod. Anatomical findings were 40 significant stenoses of the DF, 4 complete obstructions, and 10 normal arteries. These observations were compared with radiological findings: in 34 cases there was correlation between the results, in 13 cases a false negative was noted, arteriography underestimating the lesions, and in 6 cases a false positive result overestimated the extent of the atheromatous lesion. The lack of sensitivity of standard examinations of the deep femoral arteries means that it is essential to conduct oblique projections in most cases. In certain special cases, however, the authors feel that these complementary examinations can be avoided, thus eliminating their constraints. In fact, when posteroanterior angiography suggests the need for operation by an aorto-bifemoral shunt, systematic exploration of the femoral tripods can, according to the authors, replace oblique projection images. Apart from these favourable cases, oblique projections are essential during pre-operative investigations. They are also necessary to exclude any possibility of direct revascularization.

Adult↗

[Double contrast hypotonic duodenography].

Double contrast hypotonic duodenography, as carried out by the authors, is a simple and rapid examination, suitable for routine use. At the same time, it includes a double contrast study of the oesophagus and stomach. The normal appearance is easily analysed, in particular that of the great caronculus. It is a selective examination of the duodenal outline, playing an essential role in the detection of lesions of the latter as well as in adjacent organs which may alter its shape. It provides only a suggestion as to aetiology and must therefore be completed, when appropriate, by other studies.

Ampulla of Vater↗

[Experimental study of the effect of cobalt irradiation on the rabbit lung].

Rabbit lungs were irradiated with a unique dose of 3,150 rads of CO60. The time related study (from the end of irradiation to 28 days after-wards) of the ultrastructural changes in the alveolo-capillary membrane, shows that the early lesions involve first of all the endothelium, then the epithelium and the surfactant, interstitial involvement being the latest. The course of the lesions is maximal on the 7th day, while interstitial involvement appears and is amplified in the three following weeks, whereas cellular involvement completely regresses. Qualitative study of phospholipids from the pulmonary washing fluid of the irradiated lung shows early changes in the composition of surfactant (fall in lecithins and appearance of substances with similar structure) then a return to a practically normal composition around the 21st day. The nature of this early change in surfactant is debated: is it a change in surfactant secreted and/or an early change in the process of synthesis of surfactant?

Animals↗