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Biomedical subjects

M Roche

Publications and source records attributed to M Roche.

At least 73 records · Page 4Linked to original sources

Pharmacology of a gut motility stimulating enkephalin analogue.

The enkephalin analogue pentapeptide Hoe 825 (Tyr-D-Lys-Gly-Phe-L-homocysteine-thiolactone) is a mixed mu/delta opiate agonist. The peptide stimulated interdigestive gut motility at all parts of the intestine in conscious and anaesthetized animals. In dogs digestive motility, measuring mechanical activity, was stimulated with respect to segmental and propulsive properties. The canine uterus was sensitive to the enkephalin. Hoe 825 acts by i.v. or s.c. application, whereas the latter increases the duration of action significantly. The compound's effect can be blocked by naloxone indicating a receptor mediated action, which is localised peripherally. The compound is devoid of a dependence risk, because it does not penetrate into the CNS. At therapeutic doses (in the dog 0.5-2 micrograms/kg i.v.) the compound does not affect cardiovascular, renal or endocrine functions and was without effect on serum blood glucose levels in rats and rabbits.

Action Potentials↗

[Effects of lidocaine at the plasma concentrations obtained by peridural injection on atrioventricular conduction disorders].

The aim of this study was to measure plasma concentrations obtained during lidocaine extradural blocks, and to determine whether these concentrations were able to induce high degree AV blocks in patients with impaired AV conduction. In a preliminary study, 12 patients were given an extradural block with an initial bolus of 3.4 mg . kg-1 lidocaine. After repeat injections, the mean total dose was 4.7 mg . kg-1. Plasma lidocaine concentrations were determined over an 8 h period after the first injection. The study itself was carried out in 14 patients with conduction disturbances undergoing His-bundle exploration. After informed consent had been obtained, the patients received an intravenous bolus of lidocaine (1.6 mg . kg-1 over 30 s). After baseline values had been measured. His conduction and lidocaine plasma concentrations were recorded 2, 5, 10, 30 and 60 min after lidocaine injection. In the preliminary study, the peak plasma lidocaine concentration was obtained at the 15th min (1.22 +/- 0.81 microgram . ml-1). In the second series, no clinical disturbance was seen after the i.v. injection of lidocaine. The peak plasma lidocaine concentration was obtained at the 2nd min (3.05 +/- 1.44 micrograms . ml-1). No significant alteration of conduction occurred after intravenous lidocaine. It is therefore possible to conclude that bifascicular AV disturbances do not constitute a contraindication to extradural anaesthesia with lidocaine.

Aged↗

Juvenile periodontitis: healing following autogenous iliac marrow graft, long-term evaluation.

A case of juvenile periodontitis treated by autogenous bone grafting is reported. The patient, an 18-year-old female, presented with periodontal lesions around the incisors and the first lower left molar. The first molar was severely affected with bone defects at the mesial aspect and in the furcation region and, for this reason, was selected for grafting. Minced fragments of bone with its marrow, obtained from the patient's iliac crest, were implanted into the diseased periodontium. 1 year after treatment, clinical and radiological inspection revealed the presence of bone. This bone completely filled the furcation area of the tooth but only partially the mesial aspect. There was, also, significant bone fill in the supracrestal region.

Adolescent↗

[Prevention of gas microemboli during cardiac surgery. Numerical control of cardiac cavity purging by an ultrasonic detector].

Despite all precautions taken by cardiac surgeons to eliminate air remaining in the cardiac cavities and pulmonary veins at the end of cardiopulmonary bypass, many micro bubbles probably remain and pass into the systemic circulation with a risk of deteriorations of cerebral or myocardial function. Over the last four years we have used ultrasound to try to prevent the risk of preoperative gas microemboli: the machine is equipped with a detector (a quartz oscillator coupled to a piezoelectric transducer emitting a continuous beam of ultrasound at a frequency of 5 Mhz) which allows the following variables to be determined: the time interval from the onset of detection, the total quantity of bubbles (arbitrary units) in the examined regions, the quantity of bubbles detected over a given time interval which can be adjusted from 15 to 120 seconds. The passage of bubbles is also indicated by light and sound alarms. The smallest diameter of bubbles which can be detected is about 10 mu. There are periaortic probes adaptable to the calibre of the ascending aorta, transcutaneous probes for carotid artery detection and a left ventricular probe. In a preliminary series of 74 valve replacements in adults, this apparatus was used immediately after terminating cardiopulmonary bypass after we had thought that the cardiac cavities had been satisfactorily purged of air, and whilst active aspiration was continued in the ascending aorta distal to the periaortic probe: the total quantity of bubbles detected varied from less than 50 to more than 2000 AU, over a variable period of time which may exceed 20 min after termination of cardiopulmonary bypass. The total quantity of bubbles recorded after mitral valve (582 +/- 154 AU) or combined mitral and aortic valve replacement (685 +/- 167 AU) was generally greater than after isolated aortic valve replacement (335 +/- 126 AU). Therefore, after cardiopulmonary bypass, and despite all efforts at purging the air, we showed that numbers of microbubbles were ejected into the ascending aorta for a variable period of time: only some of them were eliminated by active aspiration through a trocar placed distal to the periaortic probe. The right coronary ostium was poorly protected against microbubbles because of its anatomical situation (6 cases in this series). We therefore established a protocol for the use of this apparatus to aid the purging of the cardiac cavities and pulmonary veins before stopping cardiopulmonary bypass: the manoeuvres, guided by the ultrasound probes, are performed before the left ventricle is allowed to eject blood into the ascending aorta.(ABSTRACT TRUNCATED AT 400 WORDS)

Embolism, Air↗

[The stomatological complications of Steinert's disease. Apropos of a case].

Steinert's disease is a myotonic dystrophy associated with diffuse visceral involvement. A severe hereditary disorder, it is characterised from a maxillo-facial standpoint by a special dysmorphism which the authors emphasize in the light of one case. They then suggest that a wider study of this condition might be envisaged.

Adolescent↗

Functional orthopedics: the "four pieces" and Class II treatment.

The authors describe a new functional appliance called the Chateau four pieces, which is designed for the orthopedic treatment of Class II problems during growth. The versatility of the use of the four pieces simultaneously or separately, enables the practitioner to control treatment in three dimensions. The indications and the prescription are discussed, and the results are shown.

Activator Appliances↗

[Experimental study in anesthetized dogs of the harmful effects of coronary microemboli and their prevention by drugs].

The present experiments have been performed in anesthetized dogs. They have allowed to determine the nocivity of air microembolus introduced directly in the circumflex branch of the left coronary artery. It has been suggested that to reduce post-operative disease due to microembolus at the end of an extracorporal circulation it is necessary to forbid the injection of isoprenalin and to realize a perfusion of papaverine.

Animals↗

Patterns of electrical activity in the digestive tract of the conscious cat.

1. Bipolar electrodes were permanently implanted on the gastric antrum, and on the different portions of the small intestine of each of eleven healthy adult cats receiving one meal daily. All parts of the feline gut exhibited, as in several other species, regular slow waves and alternate periods of quiescence and electrical spiking activity during the recording sessions lasting from 10 to 30 d. 2. Patterns of electrical activity characteristic of this species were identified. Both the amplitude and frequency of the antral slow-wave were related to the presence of superimposed spike bursts during fasting. A decrease in the antral slow-wave frequency and increase in the length of the duodenal plateau of slow waves after the daily meal were related to its nature. 3. In fasted state, the electrical spiking activity of the small intestine occurred as fused spike bursts of large amplitude potentials migrating slowly over short distances only 24 h after feeding. They are interspersed with short periods of irregular spiking activity. 4. These findings suggested that, except the distal part of the small intestine which showed an activity which resembled partially the migrating myoelectric complex observed in other species during the fasting state, the motility patterns of the digestive tract in the cat were not comparable to those observed in the dog or sheep. In the cat, mixing of the contents seemed to result from more or less regular spiking activity allowing their propulsion distally. The propagation over distances varying from 200 to 1000 mm of nine to eighteen daily fused spike bursts in the fasting state remains unclear but they are related to the digestive function in accordance with the displacement aborally of their origin in a prolonged fasting condition.

Action Potentials↗

Inotropic effects of potassium rich solutions of frog cardiac muscles.

1. Inotropic effects of potassium rich solutions on frog cardiac muscle have been studied bith in current clamp and voltage clamp conditions, using a double sucrose gap apparatus. 2. Potassium rich solutions cause either a positive or a negative inotropic effect, together with an increase or a decrease in the duration of the action potential, according to the preparation. 3. The phasic phase of contraction and the slow inward current are decreased in amplitude; the reversal potential of the slow inward current is shifted towards more negative values. 4. The tonic phase of contraction is first decreased, the increased; the effects are correlated with modifications of the background current, initially in the inward, then in an outward direction. 5. The tension level obtained in contracture experiments is increased or decreased, according to the direction of the changes in the background current. 6. The effects of potassium rich solutions are still observed in he presence of ouabain, suggesting that they are independent of any effect on the sodium-potassium pump. 7. The effects of potassium rich solutions are still observed when external sodium is replaced by sucrose; they disappear (except the effect on the background current) when external sodium is replaced by lithium. 8. The results, which indicate that potassium ions play a role in the regulation of the intracellular concentration of calcium ions, are discussed in relation to a possible K/Ca exchange mechanism, to the Na/Ca exchange and to the role of intracellular calcium stores.

Action Potentials↗

Effect of cholecystokinin and pentagastrin on motility and gastric secretion in the cat.

The effects of cholecystokinin (CCK; 0.25-16 IDU kg-1h-1), synthetic octapeptide of CCK (OP-CCK; 0.5-2 microgram kg-1h-1) and pentagastrin (0.5-8 microgram kg-1 h-1) on pepsin secretion and antral motility were compared in conscious cats with reference to acid secretion. The results confirmed that the 3 peptides are full agonists for acid secretion and showed that they also displayed the same action on antral motor activity in increasing the frequency and decreasing the force of the contractions. Their effects on pepsin secretion were of different efficacy, decreasing from pentagastrin to CCK and to OP-CCK which showed a very weak action.

Animals↗

[S-adenosyl-L-homocysteine: 1. Influence on sleep].

S-Adenosylhomocysteine, 0.1-20 mg/kg, influences the sleep patterns of rat, cat and rabbit by increasing the slow-wave and fast-wave sleep for 6 h. The SAH effects are increased by p-chlorophenylalanine and iproniazid and unchanged by reserpine. SAH effects are correlated with modification of norepinephrine and serotonin metabolism.

Animals↗

[Electromyographic correlations of ingesta movements in the proximal digestive tract of the hen].

Digesta transit along the oesophagus, crop and stomach has been determined by the migration of spike bursts correlated with cineradiographic observations in hens fitted with chronically implanted electrodes. The passage of digesta along the oesophagus corresponded to the propagation of isolated spike bursts. During crop filling, the activity was weak, its emptying being mediated by migrating repetitive spike bursts. A cyclically recurring electrical activity was noted for the glandular and muscular stomachs and the duodenum; their motility is described in relation to digesta movements.

Animals↗