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Biomedical subjects

F N Johnson

Publications and source records attributed to F N Johnson.

At least 37 records · Page 2Linked to original sources
PubMed1980

Effects of alkali metal chlorides on activity levels of rats in a passive exploration test.

Rats treated with alkali metal chlorides (2 mmol/kg, injected intraperitoneally) were tested for exploratory behaviour in a situation where exploration was indicated by reduced ambulatory activity. Lithium chloride significantly reduced exploration and increased ambulation as compared to sodium chloride treated control rats. Whilst rubidium chloride had similar effects to those produced by the lithium salt, these failed to reach statistical significance. The findings are discussed in the light of two hypotheses, namely that lithium attenuates the central processing of sensory information, and that rubidium acts as a nonspecific stimulant of activity.

Alkalies↗
PubMed1979

The effects of lithium chloride on response to salient and nonsalient stimuli in Carassius auratus.

The exploratory behaviour of 20 goldfish was investigated to see whether it was affected by treatment with lithium chloride. When familiar and novel stimuli were readily discriminable, lithium treatment had no effect on exploration. In a second study, using 20 fish, it was shown that when novel and familiar stimuli were less markedly different from each other, exploratory responses to the novel stimulus were reduced by lithium. The findings may be related to a general suppressant action of lithium on the extent of stimulus generalisation, or to a reduction by lithium of the animals' responsiveness to near-threshold levels of stimulation.

Animals↗
PubMed1979

Lithium effects on social aggregation in the goldfish (Carassius auratus).

In the first experiment, using 240 goldfish in pairs, the effects of lithium chloride on social aggregation were observed. It was found that aggregation was reduced between two fish when both had received lithium treatment. When, in the second experiment, 24 fish were investigated in groups of three, it was found that maximal disruption of aggregation occurred when all three fish were lithium treated, but that partial social disruption occurred following lithium treatment of two out of three fish. The results are interpreted in terms of a possible lithium induced impairment of central processing of the sensory stimuli responsible for eliciting social following responses.

Animals↗
PubMed1978

Dystrophic cardiac calcinosis in mice: genetic, hormonal, and dietary influences.

Mice of five inbred strains (BALB/c, C3H, C3Hf, DBA/2, and C57BL/6) of both sexes, mated and virginal, were examined for the incidence, severity, and location of dystrophic cardiac calcinosis (DCC) at various ages. Three hybrids, B6C3F1, C3B6F1, and CC3F1 of both sexes, all mated, were likewise studied. Excepting DBA/2, females of the inbred strains acquired the lesion at a much earlier age than males; DCC appeared in young DBA/s mice of both sexes. DCC in BALB/c mice was almost exclusively epicardial and occurred with equal frequency and severity in mated males and females, with higher incidence but lesser extent in virginal females. The occurrence was highest, the degree most severe, and the location exclusively myocardial in C3H and C3Hf mated females, irrespective of parity, whereas virginal females of these strains were entirely free of disease even after administration of exogenous progesterone. Involvement of males, also myocardial, was relatively minimal, especially in C3Hf mice. Over half the DBA/2 mice were affected, regardless of sex or mating; calcinosis appeared in the epicardium and/or myocardium, predominantly in the myocardium. Strain C57BL/6 was completely devoid of the lesion, as were the two hybrids thereof, B6C3F1 and C3B6F1. The hybrid of BALB/c and C3H showed a high incidence of minimal involvement, exclusively myocardial and limited to breeding females, indicating dominance of the C3H gene(s). Renal calcinosis was uncommon among BALB/c mice but was frequently found in C3H, C3Hf, and DBA/2 strains. Pulmonary calcinosis was rare and limited to C3H and C3Hf female breeders. Mated C3H females fed increasing amounts of fat showed a concomitant rise in incidence and severity of the cardiac lesions. Progression of the lesion from necrotic myocardial fibers to fibrocalcific masses is illustrated, as is formation of the renal deposits.

Aging↗
PubMed1976

Lithium effects upon components of activity in rats.

When lithium chloride was administered to rats several changes occurred in a number of components of activity, some of which were sex-related. There was a reduction in both ambulatory and rearing activity and in behaviour associated particularly with the mouth and nose. The findings are related to a suggestion that lithium effects on behaviour may be more subtle than hitherto thought.

Animals↗
PubMed1976

The effect of lithium chloride on one-trial passive avoidance learning in rats.

1 Expression of a one-trial passive avoidance learning response in rats was examined following injections of lithium chloride or sodium chloride before and after initial training and before the first day of testing. Five tests were given at daily intervals, 24 h after training being the time of the first test. 2. Lithium given before the first day of testing impaired response expression on the first and all subsequent days of testing; the rate of extinction was unaffected. 3. Given both before and immediately after initial training, lithium impaired response expression on the first day of testing but slowed down the subsequent rate of extinction, leading eventually to improved performance on the fifth day, as compared with placebo-treated control subjects. 4. The results are interpreted in the light of the hypothesis that lithium impaired the central processing of sensory information.

Animals↗
PubMed1975

Depression: some proposals for future research.

The argument has been advanced that pathological states of anxiety and mania are both characterized by a failure on the part of the patient to attach appropriate levels of significance to changes occurring in the immediate environment. There is, it is suggested, a tendency for environmental features to be regarded as important even though, viewed objectively, they may have little relevance to the patient and his needs. Depression, it is further proposed, may be viewed as an extreme defense reaction to the intense anxiety which results from attaching too much significance to environmental events. In depressive state, patients are often characterised by their lowered responsiveness to stimulation and their lack of interest in, or concern about, their surroundings: it may be that, in such state, information processing has been blocked or reduced. The daytime drowsiness of the depressed patients, as well as his night-time sleep disturbance and the frequently observed recurrent or cyclic nature of certain kinds of depressed state, suggest that this blocking of sensory processing may be brought about by the involuntary intervention of mechanisms responsible, under normal circumstances, for sleep induction. This view of the nature of depression has been recast into the form of five potentially testable hypotheses. Speculation is always easy; providing convincing demonstrations that those speculations are reasonable is less easy. It is in the nature of psychological investigation that laboratory-based studies distort and may even destroy the phenomena about which information is sought, and many a perfectly reasonable theory has foundered upon the rocks of translation into experimental terms. In those areas of psychology which have implications for psychiatry and the conceptualisation of psychopathological states, this danger is particularly evident: psychiatric syndromes are complex, variable, and have social referrents, but laboratory experiments are limited in their capacity to reflect all these attributes, and consequently they may never provide really adequate tests of a theory about a psychiatric state. We have to try to come to terms with this apparent impasse--in the first place by being circumspect in translating psychiatric concepts into experimental terms, and secondly by exercising caution in interpreting the results to which the experiments give rise. More importantly, however, we have to accept the essential inadequacy of the majority of experimental paradigms in psychiatric research and to regard theorizing--even when it is not linked to explicitly testable hypotheses--as having inherent value.

Affective Symptoms↗
PubMed1975

Husbandry of the "nude" mouse in conventional and germfree environments.

The "nude" mouse is a unique tool for immunologic studies. Its relatively short life span dictates the application of rigid environmental controls to increase longevity if the mouse is to assume the role of a practical experimental animal. In this paper we discussed the husbandry procedures employed to raise "nude" mice in our facilities under conventional, defined flora, and germfree conditions. Conventional and defined flora mice were raised on laminar flow stay-clean rocks, and germfree "nudes" were housed in self-contained germfree isolators. The major cause of morbidity and mortality among conventional and defined flora "nude" mice was fulminating hepatitis. We presented evidence that the etiologic agent of the disease was mouse hepatitis virus (MHV). Germfree "nude" mice were completely free from viral and bacterial diseases.

Animals↗