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Biomedical subjects

G Sørensen

Publications and source records attributed to G Sørensen.

13 recordsLinked to original sources
PubMed1988

Stereotyped behaviour in animals induced by stimulant drugs or by a restricted cage environment: relation to disintegrated behaviour, brain dopamine and psychiatric disease.

Stereotyped behaviour can be produced in animals both by stimulant drugs (amphetamine, methamphetamine, cocaine, etc.) and by a restricted cage environment. Strong evidence indicates that the effect of stimulant drugs is mediated through a primary effect on brain dopamine, and further knowledge is now being acquired through studies on dopamine receptors, tolerance and reverse tolerance to amphetamines and the neural connections of dopaminergic sub-systems with other sub-systems in the brain. The forms of stereotypy induced by a restricted cage environment have been compared with other effects of this type of environment on behaviour and general health. This has led to a hypothesis that stereotyped behaviour may function as a survival (or defence) strategy in an unfavourable milieu. Some evidence indicates that brain dopamine is also involved in the mediation of stereotyped behaviour induced by the environment. The relevance of these results in clinical psychiatry is discussed. Stereotypy (and related disintegrated behaviour) is a well known feature of several mental diseases.

Amphetamines↗
PubMed1987

Stereotyped behaviour, hyperaggressiveness and "tyrannic" hierarchy induced in bank voles (Clethrionomys glareolus) by a restricted cage milieu.

This investigation was originally conceived as a further development of studies made with the "amphetamine model" of psychosis. Since amphetamine itself seemed to be the most important flaw in this model, it was judged promising to study abnormal behaviour in animals elicited without the use of drugs. Bank voles were placed in two different cage milieux, a restricted milieu approaching usual laboratory conditions for experimental animals, and an enriched milieu offering opportunities for satisfaction of natural behavioural (ethological) needs. During an experimental period of 6 months normal behaviours (known from the ethogram of the bank vole) and abnormal behaviours were recorded in eight 5-min observation periods of each cage. Social structure (hierarchy) was studied by the intruder method and social function (peaceful or tyrannic hierarchy) by inspection of the subordinate voles for wounds. Stereotypies, hyperaggressive behaviour and tyrannic hierarchy, replacing normal behaviour and social structure, were seen frequently in the restricted milieu, but only occasionally in the enriched milieu (differences highly significant). It is concluded that these findings indicate possibilities for further development of the basic studies of abnormal behaviour made by means of the "amphetamine model" of psychosis. Opportunities exist for investigation of the interaction of milieu factors with genetic, pharmacological and other factors relevant to the development, prevention and treatment of abnormal behaviour and mental disease.

Aggression↗
PubMed1986

Relationship between penicillinase production and the in-vitro activity of methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin, and cephalothin against strains of Staphylococcus aureus of different phage patterns and penicillinase activity.

A total of 157 strains of Staphylococcus aureus of different phage patterns and penicillinase production were investigated for their susceptibility to methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin and cephalothin by an agar dilution method. Only strains of the 52, 52A, 80, 81 complex had significantly higher IC-50 values than the rest of the strains. No correlation was found between penicillinase production and the IC-50 values. Penicillinase susceptibility divided the antibiotics into two groups: one including methicillin, oxacillin and cephalothin, and the other included dicloxacillin, cloxacillin and flucloxacillin. Nineteen strains of S. aureus which existed in both a penicillinase producing and a penicillinase non-producing form were examined for susceptibility to the six antibiotics. The difference between penicillinase positive and penicillinase negative variants was especially marked for flucloxacillin and cephalothin. Methicillin induction prior to susceptibility testing had only a minor influence on the results. Investigation of the stability of methicillin and the four isoxazolyl penicillins against penicillinase production by 37 strains of S. aureus showed methicillin to be the most stable antibiotic. This was followed by dicloxacillin, cloxacillin, flucloxacillin, and oxacillin in that order. The order of stability was identical and independent of phage pattern and quantitative penicillinase production.

Bacteriophage Typing↗
PubMed1980

Pharmacokinetics of azidocillin in healthy adults.

Two cross-over studies with azidocillin-sodium were carried out on healthy volunteers. In the first, we gave single doses of 375 mg, 750 mg, 1500 mg as tablets, 750 mg as a suspensions, i.m. and i.v. injections of 799 mg, and a course of 750 mg tablets twice daily for 14 days. In the second study, two 750 mg tablet batches were compared with the same dose i.v. Mean peak concentrations after 750 mg as tablets were 6.5-8 microgram/ml, as suspension 12.4 microgram/ml, and i.m. 18.5 microgram/ml. The urinary recovery of active antibiotic was 37-40% of the dose after the tablets, and nearly 50% after i.v. dosage. Thus, urinary elimination after the tablets was 75-83% of the amount eliminated after i.v. dosage. Bioavailabilities stipulated on the basis of the area under serum concentration curves in comparison with i.v. dosage were 57-60% for the tablets and 64% for the suspension. The bioavailability of the i.m. dose was comparable to that of the i.v. injection. The relatively small difference between the tablets and the suspension indicates that the tablets had favourable biopharmaceutical properties. Serum half-life of azidocillin was 0.6-0.7 h after the i.v. doses. For the other dosage forms, the half-life values varied between 0.6 and 1.1 h. The distribution volume Vd,beta ws 27-34 l after i.v. administration.

Adult↗
PubMedDate not supplied

[The self-regulation process, adjustment and defense. Interdisciplinary study].

The study of the processes of self-regulation and defense may serve as an example illustrating the interdisciplinary research in psychiatry. Belying on the topography of mental disturbance as described by the systemal method, this study can profit from the findings of animal ethology and oceanographyt++ and thus conceive of the diversity and integration of the defense mechanisms of living systems beloging to different levels in the hierarchy of species. These insights may contribute to a refinement of the analysis of the human defense mechanisms met in psychiatry. As an example of this an analysis of phobic avoidance is related.

Adaptation, Psychological↗