Biomedical subjects

R Lalonde

Publications and source records attributed to R Lalonde.

At least 145 records · Page 8Linked to original sources

PubMed1991

Effects of ketamine and 1-glutamic acid diethyl ester on concept learning in rats.

The effects of ketamine, an NMDA receptor antagonist, and 1-glutamic acid diethyl ester (LGDE), a non-NMDA glutamate antagonist, were evaluated in the acquisition of concept learning in a water maze. In concept learning, the rats must locate an invisible platform whose location changes from day to day. In spatial learning (Morris task), the rats must locate an invisible (or visible) platform whose location does not change. Ketamine increased quadrant entries at 5, 10 and 20 mg/kg, and latencies at 10 and 20 mg/kg on the final two days of training on the concept task. At 5 mg/kg ketamine disrupted concept learning but not spatial learning or visuo-motor coordination as assessed by invisible and visible platform conditions of the Morris maze. Progressively higher doses of ketamine affected first the invisible condition and then the visible platform condition. On the other hand, LGDE did not affect the Morris task at any dose. However, there was no decrease in latencies over days in concept learning at the two highest doses (240 and 360 mg/kg) of LGDE. Thus LGDE appeared to slow down decision time in the concept task but not the spatial task in the absence of an effect on quadrant entries in any version. These results indicate that NMDA receptors are involved in spatial and concept learning. Non-NMDA receptors appear to be involved only in concept learning.

Animals↗

PubMed1991

Death from bulbar involvement in Friedreich's ataxia.

Cheyne-Stokes breathing occurs in patients with Friedreich's ataxia. In some cases, this form of periodic breathing may be caused by degenerative changes at the bulbar level. In view of decreased levels of glycine in the spinal cord in patients with Friedreich's ataxia, though medullary levels have not been measured, it is hypothesized that glycine (and perhaps other inhibitory amino acids) reverses Cheyne-Stokes breathing and could perhaps prolong life expectancy in patients with Friedreich's ataxia.

Animals↗

PubMed1990

Effects of l-glutamic acid diethyl ester on discrimination learning in rats.

The acquisition of a visuo-tactile simultaneous discrimination task for food reward was evaluated in male albino rats given 0, 120, 240 and 360 mg/kg of l-glutamic acid diethyl ester, an antagonist of quisqualate and kainate receptors. There was an increase in the number of trials to reach the criterion and in the number of errors at the two highest doses of l-glutamic acid diethyl ester in comparison to the two lowest doses. These results indicate a possible role for non-NMDA amino acid receptors in discrimination learning.

Animals↗

PubMed1990

Tuberculous pancreatitis.

We describe a case of severe tuberculous pancreatitis in a 26-year-old woman with miliary tuberculosis. Recognition of this complication is important as it may interfere with adequate absorption of anti-tuberculous drugs and it can lead to unnecessary laparotomy.

Adult↗

PubMed1990

Long-standing symptomatic cryptosporidiosis in a normal man: clinical response to spiramycin.

A healthy immunocompetent 26-year-old man developed prolonged symptomatic cryptosporidiosis. He only achieved clinical improvement after treatment with spiramycin. Other family members suffered from chronic undiagnosed diarrhea, and resolution occurred only after a trial of spiramycin. Thus, Cryptosporidium had provoked a prolonged symptomatic infection in a normal host; spiramycin therapy was required for parasite eradication and clinical cure, and a therapeutic trial with spiramycin was beneficial for family members with chronic undiagnosed diarrhea. Many infections with Cryptosporidium have serious morbidity, and thus, spiramycin may be more generally indicated in the treatment of this infection.

Adult↗

PubMed1989

Exploration and habituation in Purkinje cell degeneration mutant mice.

Purkinje cell degeneration (pcd) mutant mice lose virtually all Purkinje cells. It was found that the pcd mutants did not show within-sessions habituation in terms of hole-poking responses. This type of perseverative responding has been found in rats with limbic system damage and implies a role for the cerebellum in behavioral inhibition.

Animals↗

PubMed1989

The history of a comprehensive pharmacokinetic service.

This paper reviews the 10 years of providing a Clinical Pharmacokinetic Service (CPS) at the Ottawa General Hospital. The history of the service is followed from the early days of selective monitoring of two drugs to the present comprehensive level of monitoring of essentially all drug concentrations analyzed in the hospital. The administrative development is presented, including that of the Subcommittee on Pharmacokinetics. A justification study is described, the results of which indicated 92 percent acceptance of the CPS' recommendations. An effort to withdraw service for digoxin was unsuccessful in that a concurrent study indicated a deterioration in the appropriateness of digoxin prescribing. Several quality assurance techniques are discussed, including a recent audit on predictability. Finally, the education and research links are summarized. Based on the experience of the authors, it is concluded that a comprehensive CPS is an indispensable clinical service.

Digoxin↗

PubMed1988

Spontaneous alternation and exploration in weaver mutant mice.

Weaver mutant mice engaged less in motor activity and hole poking. Weaver mice alternated spontaneously in a 4-trial but not a 2-trial test. These results are similar to those of a previous study with staggerer mutants, in that both are less active. However, weaver mutants are less affected in the spontaneous alternation measure.

Animals↗

PubMed1988

Does the mutant mouse lurcher have deficits in spatially oriented behaviours?

Lurcher mutant mice, in comparison to normal mice, had directional deficits in the Morris milk tank test and in a water-maze spatial alternation task. The lurcher mutants also showed an initial lack of spontaneous alternation and did not alternate in one behavioral condition when the inter-trial interval was lengthened. Lurcher mice were slower to learn a simple left/right position response to escape a T-maze by swimming although their motor coordination was good. Paradoxically, no deficit was observed in learning to select a left or right position for food in the same T-maze although the goal-directed locomotion was very ataxic. Overall, the lurcher mutants have difficulty in guiding themselves in the water toward a visible goal.

Animals↗

PubMed1988

Spontaneous alternation and exploration in staggerer mutant mice.

Staggerer mutant mice were found to be less active in terms of motor activity in a maze, hole poking and rearing. Staggerer mutant mice also showed a lack of spontaneous alternation in both 2-trial and 4-trial tests. A lack of spontaneous alternation in this mutant may be due to a deficit in response inhibition or in spatial orientation, similar to that of animals with limbic lesions.

Animals↗

PubMed1987

Delayed spontaneous alternation in Purkinje cell degeneration mutant mice.

Purkinje cell degeneration (pcd) mutant mice lose cerebellar Purkinje cells. It was found that pcd mice, contrary to normal mice, did not alternate spontaneously at any of 3 inter-trial intervals (15 s, 3 or 6 min). Deficits in spontaneous alternation are typical of animals with brain damage in areas important in spatial learning. Results are discussed in terms of a role for the cerebellum in spatially mediated behavior and behavioral inhibition.

Animals↗

PubMed1987

Spontaneous alternation and habituation in Purkinje cell degeneration mutant mice.

Purkinje cell degeneration (pcd) mutant mice were found to be as active as normal mice in a T-maze. The pcd mutants, contrary to normal mice, did not alternate spontaneously in either a 2-trial or a 4-trial test. Results are discussed in terms of a role for the cerebellum in behavioral inhibition and visuo-spatial organization.

Animals↗

PubMed1987

Motor abnormalities in weaver mutant mice.

Weaver mutant mice lose mainly cerebellar granule cells. Motor abnormalities included less activity in a hole-board test and a loss of balance in two equilibrium tests. It was noted that the weaver mutants also displayed paw clasping responses when held by the tail of a sort never seen in normal mice. The role of the cerebellum in these abnormalities is discussed.

Animals↗

PubMed1987

Motor abnormalities in staggerer mutant mice.

Staggerer mutant mice spontaneously lose both Purkinje and granule cells of the cerebellum. Motor abnormalities included less activity for an exploratory task and loss of balance in two equilibrium tests. It was observed that staggerer mutants exhibited paw clasping and limb crossing responses when held in the air by the tail, of a sort never seen in normal adult mice. The role of the cerebellum in these abnormalities is discussed.

Animals↗

PubMed1987

Object exploration in staggerer mutant mice.

Staggerer mutant mice, which lose Purkinje and granule cells in the cerebellum, were found to explore for a longer period of time than normal mice a novel object placed in a familiar environment. There was no difference between the two groups in terms of general motor activity. These results are discussed in regard to a role for the cerebellum in behavioral inhibition and emotion.

Animals↗

PubMed1987

Exploration and spatial learning in staggerer mutant mice.

Staggerer mutant mice, that lose cerebellar Purkinje cells and granule cells and inferior olive neurons, were evaluated in tests of spontaneous alternation and maze learning. It was found that, contrary to normal mice, the staggerer mutants did not alternate spontaneously and had deficits in the acquisition of maze learning. It is hypothesized that the olivocerebellar system has a role in visuo-spatial organization.

Animals↗

PubMed1986

Navigational deficits in weaver mutant mice.

Weaver mutant mice have selective degeneration of cerebellar granule cells. In comparison to normal mice, the weaver mutants made more errors and took a longer time to reach a platform in a water-maze. Results are discussed in terms of a role for the cerebellum in spatial orientation.

Animals↗

PubMed1986

Delayed spontaneous alternation in weaver mutant mice.

Weaver mutant mice alternated above chance levels but less often than normal mice in a 2-trial spontaneous alternation test. When the inter-trial (or retention) interval was manipulated, the weaver mutants alternated above chance levels only at the shortest (15 s) but not at the longest (4 or 5 min) intervals, contrary to normal mice that alternated above chance levels at all 3 intervals. Results are discussed in terms of a role for the cerebellum in spatial working memory.

Animals↗