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Biomedical subjects

E Michel

Publications and source records attributed to E Michel.

108 records · Page 6Linked to original sources
PubMed1981

New total synthesis and high resolution 1H NMR spectrum of platelet-activating factor, its enantiomer and racemic mixtures.

A new method of synthesis of octadecyl platelet-activating factor (PAF; 1-O-octadecyl 2-O-acetyl sn-glycero-3-phosphorylcholine) is described. Its advantage is to proceed by way of the 'lyso-PAF' which may be substituted by various groups, while avoiding the inconveniences of the total synthesis already described. Moreover, the intermediates in synthesis are easier to purify, with better yields. The platelet-aggregating activity of synthetic PAF, is enantiomer (3-O-octadecyl) and racemic mixtures were 2.7 . 10(-10), 1.7 . 10(-7) and 2.2 . 10(-10) M, respectively. These results indicate the stereospecificity of platelet activation induced by PAF.

Animals↗
PubMed1981

Synthesis and biological activity of some structural analogs of platelet-activating factor (PAF-acether).

Platelet-activating factor (PAF-acether), a mediator of anaphylaxis and inflammation, is a 1-O-alkyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine. Some analogs of PAF-acether were prepared by total synthesis or by partial synthesis from commercially available phospholipids and tested for platelet aggregating activity. This study indicated that the ether linkage at the position 1 of sn-glycerol and the short acyl chain at position 2 are structural features required for biological activity.

Animals↗
PubMed1980

[Contraception and liberal medical acts. The results of a national enquiry carried out by INSERM 1974-1975 (author's transl)].

The authors examined the part taken by contraception in a liberal practice in France arising out of a national enquiry on liberal medicine in France which was conducted by INSERM in 1975 and which was concerned with the medical activity of a random sample of 1150 doctors carrying out 2 100 total acts. They particularly analysed how these acts were distributed between general practitioners and gynaecologists. It is estimated that in 1975 there were 4.6 million medical liberal acts for contraception in women between 15 and 44 years of age, which worked out at about 1 per person every 8 to 9 months. General practitioners performed about 55 per cent of these acts. The geographical situation (whether it is urban or rural) is the main determinant of the choice of general practitioner or gynaecologist and not the age of the women or their professional activity. Certainly from the point of view of doctors contraception plays an important part in the activity of gynaecologists (20 to 25 per cent of their acts) whereas it remains a weak part of the activity of general practitioners (approximately 1 act every 2 or 3 days). Gynaecologists are inversely busy according to the amount of contraception they practise, but one must consider that there is a balance between contraceptive acts and obstetrical acts. As far as general practitioners are concerned, on the other hand, the year they qualify is the most important, since the younger doctors give up more time for this kind of activity than the older ones.

Adolescent↗
PubMed1979

The use of acridine orange for testing blood platelet integrity.

Two processes are involved in the accumulation of acridine orange in human blood platelets. One follows a diffusion like kinetics and is independent of the ATP level whereas the second one can be completely abolished by ATP depletion. The acridine orange incorporation rate seems to be a suitable parameter for testing platelet integrity. It reflects very sensitively the influence of the preparation method as well as of anticoagulating substances used on the stability of platelet suspensions. The rates of acridine orange incorporation and of aggregation were measured in platelet-rich plasma and in saline suspended platelets after gel filtration, respectively, over a period of 120 min storage. Both rates are influenced to a different degree by anticoagulating agents such as citrate, heparin and EDTA. When contact with anticoagulating agents during platelet preparation is avoided, platelets show a constant acridine orange incorporation and aggregation during storage and the smallest morphological alteration.

Acridine Orange↗
PubMed1977

[The effect of several sexual steroids, 2-bromo-ergokryptin and lisurid-hydrogenmaleate an the postpartum concentration of serum prolactin and lactation (author's transl)].

The effect of Ablacton, Estrovis 4000, 2 Brom-alpha-ergokryptin (Cb 154) and of Lisurid-hydrogenmaleate (LHM) on lactation and the serum concentration of prolactin postpartum was studied. 10 normal nursing postpartum patients served as control. LHM was tested in a double blind study compared to placebo. The serum prolactin (PRL) was determined daily for the first 10 postpartum days by radioimmunoassay. Inhibition of lactation was consistent with Cb 154 (89% of the cases). Within two to three days after the onset of treatment with Cb 154 the changes of pregnancy in the breasts had completely subsided. The sexual steroids resulted in inhibition of lactation in 60% of the postpartum patients but mastodynia continued. LHM showed no difference from group taking placebo. The serum prolactin levels postpartum remained as high as a nursing mother's or rose with the administration of steroids. The administration of Cb 154 resulted in a drop of the serum prolactin to non-pregnant levels with in 2 days. The serum prolactin levels under treatment with LHM were not different from the group slowly. In nursing mothers, the stimulus of suckling maintain the pituitary secretion of prolactin as showed by higher serum prolactin levels and a slower decreased to normals than in the non-nursing mothers.

Bromocriptine↗
PubMedDate not supplied

[Pethidine analgesia and cerebrovascular circulation in very small premature infants].

Aim of the study was the assessment of possible side effects of analgesia with pethidine on the intracerebral circulation of very immature preterm infants. For this purpose the blood flow velocity in the internal carotid artery, basilar cerebral artery and the anterior cerebral artery was measured by pulsed Dopplersonography before and 5-10 min after i.v. injection of 1.0 mg/kg pethioine on 10 preterm infants with a gestational age of 24-30 weeks. Furthermore values for the parameter mean arterial blood pressure, heart frequency and tcpCO2 were obtained. None of the measured parameters showed a significant difference with the i.v. bolus injection of pethidine. As even very immature preterm infants do feel pain and can show potential dangerous physiological pain reactions and as this study proves the tolerance of the drug, analgesia with morphine derivates is recommended.

Blood Flow Velocity↗
PubMedDate not supplied

[Cerebrovascular circulation in premature infants in relation to theophylline therapy].

The impact of 6 mg/kg resp. 1.5 mg/kg i.v. administered Euphyllin (containing ca. 80% theophylline and ca. 20% ethylenediamine) on intracerebral circulation was investigated in 20 (gestational age 25-37 weeks) resp. 10 preterms (26-33 weeks). For that purpose blood flow velocity was measured in three intracerebral vessels (Internal carotid artery, internal jugular vein, and anterior cerebral artery) by transfontanellar pulsed Doppler ultrasonography before, 2 min after and 6 min after the drug was given. Vmax (mean peak velocity) decreased by 25% in the internal carotid artery, by 26% in the internal jugular vein, and by 17% in the anterior cerebral artery. With 1.5 mg/kg a decrease could only be evaluated in the internal carotid artery (by 10%). The reduction of cerebral blood flow induced by theophylline is due to both the simultaneous decrease of pCO2 (by 3 mmHg in our study) and a direct vasoconstrictive effect of the drug on the cerebral resistance vessels. Effects of theophylline on systemic circulation are not responsible for its influence on cerebral circulation. Regarding the physiological variability and ischemic threshold of the human brain the impact of theophylline on neonatal cerebral circulation must be estimated as a tolerable risk.

Blood Flow Velocity↗
PubMedDate not supplied

[Disorder of the blood-brain barrier caused by mannitol poisoning in an infant with encephalotoxicosis].

The clinical course of a mannitol intoxication in a 5-month-old infant is reported. Mannitol measurements were performed by gas-chromatographic-mass-spectrometric analysis. The role of the osmolal gap as a simple diagnostic tool in mannitol intoxication was underlined by comparison to serum mannitol levels. Mannitol elimination was analysed by measuring mannitol levels in urine, ultrafiltrate, and peritoneal dialysis outflow. The highest concentrations were found in urine (approx. 300% serum values) and the lowest in peritoneal dialysis outflow (approx. 50% serum levels). "Total body Mannitol" was calculated each day from body weight, hydration, and serum mannitol levels and opposed to the amount eliminated via urine, ultrafiltration, and peritoneal dialysis. The results were only compatible with a volume of distribution of approx. 5.3 1, representing total body water at a lean body weight of 7 kg. It could thus be demonstrated that the sudden fall of serum mannitol levels from 19.6 mg/ml to 5.5 mg/ml without dialysis treatment in an anuric patient was due to a leak of mannitol into the intracellular compartment.

Acute Kidney Injury↗
PubMedDate not supplied

[Simple nuclear magnetic resonance tomography compatible pediatric ventilator system. Ventilation and MRI].

BACKGROUND: The widespread tunnel-shaped construction of magnetic resonance tomography (MRT) machines requires a remote device free of metal for ventilation of the comatose patient not breathing spontaneously. PATIENT AND METHOD: In order to ventilate a 3 year old boy, we modified an open-circuit bag ventilation system according to requirements. Fresh gas was insufflated into the patient's tube connector using a 6 m small sized silicon rubber hose, thus providing the required distance from the metallic gas supply. A second branch of the tube connector was connected to 1 m of wide tubing ending in the bag (Kuhn-system). RESULTS: The system proved its competence during a 1 hour session, and did not result in MRT artefacts. CONCLUSIONS: Due to the system design, the extension of the tubing does not result in significant dead space ventilation provided there is adequate fresh gas flow. The proposed system is simple in construction, easy to handle, and ideal for use on comatose children urgently requiring MRT. Thus, any delay due to preparations for anaesthesia and mechanic ventilation can be avoided.

Child↗
PubMedDate not supplied

Use of an artificial neural network (ANN) for classifying nursing care needed, using incomplete input data.

BACKGROUND: In German nursing insurance, the act of classifying the client into four categories of disability is based on legally defined distinct criteria. When classifying deceased persons it is often impossible to collect all the required information. PRIMARY OBJECTIVE: We aimed to determine the ability of an artificial neural network (ANN) to calculate the category of disability, to investigate the response of the ANN to input items of different nature, quantity and data quality, and to estimate the minimum number of training data required. RESEARCH DESIGN: The investigation was conducted as a retrospective observational study. METHODS AND PROCEDURES: The analysis was based on routine records of 14000 adult clients of the nursing insurance. Several ANNs were trained, varying nature, number and quality of the input items as well as the size of the training data set. Each ANN's classification competence was tested on independent validation data, judging the ANN's conformance to the result of the individual expert assessment, using kappa statistics. MAIN RESULTS: Fed with all 30 input items available, the net classified 80% of cases correctly (weighted kappa = 0.78). Using three input items, weighted kappa was 0.63. Severe misclassification (deviation by more than one category in either direction) ranged between 0.2% (all 30 input items) and 3.7% (3/30 items). The less complete the individual input items were, the less accurate was the net's estimate. A 20% rate of missing values was well tolerated. A training set comprising 500 cases was adequate. CONCLUSIONS: The input item set inherits redundancy. The ANN's ability to correctly respond to subsets of input items makes it a powerful tool in quality control. In the categorization of deceased persons when only an incomplete input item set is available, the ANN can achieve satisfactory results.

Activities of Daily Living↗
PubMedDate not supplied

[Proposed design for a randomized effectiveness study in social medicine].

For ethical, medical, financial as well as legal reasons scientific evaluation is mandatory in the field of public health or rehabilitative medicine. We prototype a fictive randomised and controlled study, taking into account numerous concerns against such a type of statistical analysis in the special field. The theoretical benefits of the study design do well balance its modest cost.

Data Interpretation, Statistical↗