Fruit or aposematic insect? Context-dependent colour preferences in domestic chicks.

Colours are common stimuli in signalling systems. Requirements to function well as a signal sometimes conflict between different signallers, and the same colour stimulus is used to convey completely different messages to the same receiver. Fruits and aposematic insects both use red coloration as a signal, in the former case to signal profitability and in the latter case as a warning signal. In two experiments, we investigated whether the domestic chick, an omnivorous predator, differed in its unconditioned preference or avoidance of red and green stimuli depending on whether or not the stimulus was an insect. The experiments were designed as preference tests between red and green painted prey. The prey were live insects and artificial fruits (experiment 1), and, to investigate the effect of movement, live and dead insects (experiment 2). The chicks did not show any difference in pecking preference between red and green when fruit-like stimuli were used, but when the prey were insects, green prey were strongly preferred to red prey, and prey movement did not affect this bias. Thus, young chicks may recognize prey as insects and then discriminate between different prey colorations, or one type of food may elicit an unlearned colour preference-avoidance response that is absent with another type of food.

Decision time and prey gregariousness influence attack probability in naïve and experienced predators.

Aposematic coloration often has an element of conspicuousness. One suggested benefit of conspicuousness is that it enables the prey to be detected at a greater distance, allowing a predator more time to make a correct decision about attacking it and thus reducing possible recognition errors made by predators. I conducted an experiment, with chicks, Gallus gallus domesticus, as predators on live aposematic and nonaposematic prey, to investigate the effects of decision time and signal size on predator sampling behaviour. The chicks were subjected to different degrees of competition to influence how quickly decisions had to be made. Chicks in four treatment groups, either in the presence or absence of a competing chick, were presented with either solitary prey or prey in groups. In the presence of a competitor, chicks attacked the prey more often and more quickly and needed more attacks before they started to avoid the prey. With prey in groups, chicks took longer to attack, attacked less often, learnt to avoid prey more quickly and killed fewer aposematic prey. This experiment provides evidence for the importance of time and signal size for predators' attack decisions. More time to view prey prior to attack could produce a stronger image and thus encourage avoidance learning and produce a stronger neophobic avoidance effect. Copyright 2000 The Association for the Study of Animal Behaviour.

Pharmacological studies on perazine and its primary metabolites.

The study served to answer the question whether metabolites possibly contribute to the clinical actions of the neuroleptic drug perazine. The primary metabolites demethylperazine and perazine sulfoxide were investigated with regard to influences on behavior in mice, to an antiemetic action in dogs, and to a modification of the pressor effect of noradrenaline in rats. In contrast to perazine, none of the metabolites exhibited effects that can be interpreted to indicate neuroleptic or antidepressive properties of the compounds.

[Traffic safety in treatment with dosulepin]. / Verkehrssicherheit unter Dosulepin-Behandlung.

Forty-eight healthy volunteers aged between 18 and 61 years, 24 men, 24 women, received dosulepin (Idom) or placebo in a randomized fashion over a period of 16 days. The study was designed as a double-blind, placebo controlled parallel trial. The single daily dose of 75 mg was given in the evening. In order to assess driving ability under medication, the following parameters were examined before the study and on days 3, 10 and 17: visual orientation, concentration stress toleration while performing reaction tasks, eye-hand coordination, vigilance, accuracy and speed of reaction, and sense of wellbeing. Apart from a mild loss of concentration and decrease in the sense of wellbeing, none of the other parameters showed any significant changes as compared with placebo. The results are in good agreement with those of earlier relevant trials with other antidepressants. The results of the present study form the basis for an assessment of the driving ability of the individual patient receiving dosulepin.

Experimental studies and clinical experiences on the dependency potential of chlormethiazole.

The dependency potential of chlormethiazole has been assessed on the basis of animal studies (rat and monkey) and an extensive analysis of human cases reported in the international clinical literature covering a period of 17 years. The results of the animal studies do not show any major physical or psychological dependence on chlormethiazole. Clinical studies of case reports suggest that the evidence for "primary" dependence on chlormethiazole is weak, as most of the analysable cases had a previous history of alcohol and/or other drug abuse/dependence. Moreover, in a high proportion of these cases there was evidence of simultaneous alcohol and/or other drug abuse. It should be stressed that in this group of patients the dependence on chlormethiazole was invariably reported in connection with long-term out-patient medication, that is, in a way that was not in accordance with recommendations for use of the drug in "dried out" alcoholics and/or drug addicts. Reports of chlormethiazole abuse/dependence from the alcohol/drug addiction indication are may involve a population particularly prone to addiction and, therefore, be unrepresentative for general assessment. Conversely, the findings in animal studies provide indirect support for the favourable clinical experiences with chlormethiazole in the geriatric, psychogeriatric and obstetric indication areas where chlormethiazole has been used extensively for more then a decade in a problem-free manner. The risk which applies to long-term use in alcoholics and/or drug addicts or the emotionally unstable, because of their "dependency proneness", does not seem to apply to the treatment of conditions, such as insomnia and agitation, in the elderly in whom the drug has been found to be very useful by various investigators.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase I metabolism of imipramine by microsomes of small intestine in comparison with metabolism by liver microsomes.

The metabolism of imipramine was investigated by the incubation of C-14 labelled compound in Krebs-Ringer bicarbonate buffer with microsomes of small intestine and of liver from guinea pigs. Imipramine and its metabolites were extracted with chloroform, separated by TLC and determined quantitatively by direct scanning with a TLC Linear Analyzer. With intestinal microsomes, the following metabolites could be identified: DMI, 2-OH-IMP, IMP-N-oxide. DMI is the main metabolite. The same metabolites appeared after incubation with liver microsomes, but the proportions were different: the N-oxide formation was predominant, followed by N-demethylation and hydroxylation. The formation of DMI and 2-OH-IMP seems to follow Michaelis-Menten kinetics, both in assays with intestinal and with liver microsomes. The liver/intestine ratio of DMI and 2-OH-IMP formation is proportional to the cytochrome P-450 ratio in the microsomes, in contrast to N-oxide formation.

[Drug monitoring in psychiatry (author's transl)]. / Drug Monitoring in psychiatrischen Kliniken. Bericht der Arbeitsgruppe für Medikamenten-Uberwachung in der Psychiatrie.

The Study Group for Drug Surveillance in Psychiatry (AMUP) has been working since July 1978 as a task force group of the "Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie" (AGNP). A protocol was designed for the initiation of drug monitoring in psychiatric hospitals. With support of the Bundesgesundheitsamt, Berlin, the first part of this project was started as a practicability study in the psychiatric hospitals of the Universities of Berlin, Göttingen, and Munich and in the municipal hospital of Schleswig. The study includes 7650 in-patients. It is based on the following methods: intensive drug monitoring, organized spontaneous monitoring of adverse drug reactions and registration of drug applications. This drug monitoring system in psychiatry will be expanded to other psychiatric hospitals, and eventually to out-patient clinics as well as private practices within the next two years.

Effects of furosemide and spironolactone on the behavior of morphine-tolerant rats.

In morphine-tolerant rats, a reappearance of morphine catalepsy and a disappearance of the turning behavior characteristic of brain-lesioned tolerant animals were observed under the influence of furosemide and spironolactone. The administration of spironolactone together with daily morphine treatment resulted first in an intensification of the morphine symptoms as measured by catalepsy and a retarded appearance of tolerance, typically characterized by a shift from catalepsy to turning movements in animals with single-sided brain lesions. Nontoxic doses of spironolactone raised the sensitivity of morphine-tolerant rats so that previously tolarated morphine doses become lethal.

[The problem of animal models for psychiatric conditions, as illustrated by the immobilization reaction (catalepsy) in the rat (author's transl)]. / Die Immobilisationsreaktion der Ratte als tierexperimentelles Modell für die Katatonie

According to Venables the span of psychotic processes extends from a low level of arousal with an increased reactivity toward sensory stimuli to a high level of arousal with a reduced reactivity toward sensory stimuli. The level of arousal and the degree of reactivity, or breadth of attention, are apparently controlled by a regulatory mechanism which increases the threshold for sensory input in threatening situations. Any factor producing an electroencephalographic arousal reaction leads to a narrowing of attention. Underestimation of the size of a given object is an expression of such a reduction in the span of attention. Various authors have found a reduction in size-constancy in schizophrenics, in particular in patients exhibiting a merkedly reduced contact with their environment. A model is described in which a strong sensory stimulus induces a state of immobilization in rats treated with a low dose of morphine. Electroencephalographic recordings show that the initial state of arousal induced by peripheral stimulation is replaced by high-amplitude slow-waves and spindles as the state of immobilization develops. The current results suggest that the sensory stimulation leads to excitation of the ascending reticular formation and via the Centrum medianum and the Nucleus centralis, to activation of the striatal system, resulting in catalepsy. It would thus appear that the reticular formation and the striatum alternate in excercising a control function over the state of arousal. This would be a logical way of limiting over-reaction, which can be demonstrated most simply on the motoric response. It seems justified, therefore, to assume a relationship between catatonic stupor and the immobilization induced by stimulation. This concept is supported by the observation that of all the compounds investigated only clozapine is capable of inhibiting the immobilization in the rat model. Clozapine is a powerful antipsychotic agent with a pronounced inhibitory effect both on the reticular arousal reaction and on the schizophrenic catatonia.