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Biomedical subjects

D Morrison

Publications and source records attributed to D Morrison.

At least 37 records · Page 2Linked to original sources
PubMed1989

High-level vancomycin-resistant enterococci causing hospital infections.

Nosocomial infection or colonization due to enterococci with high-level resistance to vancomycin (minimal inhibitory concentrations [MICs] between 64 and greater than 2000 mg/L) has occurred in 41 patients with renal disease. These vancomycin-resistant enterococci were cultured from many sources including blood. All but one strain contained one or more plasmids ranging in molecular weight from 1.0 to 40 Megadaltons (MDa). Vancomycin resistance was transferable by conjugation to a susceptible recipient strain of Enterococcus faecalis but this was not always associated with plasmid DNA. The emergence of transferable high-level vancomycin resistance in enterococci causing significant clinical infections is of particular importance since vancomycin is widely regarded as a reserve drug for the management of infections with multi-resistant Gram-positive organisms.

Acute Kidney Injury↗
PubMed1989

Preacademic screening for learning and behavior problems.

The relationship between socioeconomic status (SES) and behavior problems in children at risk for developing learning difficulties was investigated by screening 1106 children who were completing kindergarten and identifying 292 as being at-risk. Data on SES, behavior problems, and preacademic reading skills were obtained on 204 at-risk children and 181 non-at-risk controls. A larger proportion of children from upper SES made up the non-at-risk sample and a smaller proportion of upper SES children were found in the at-risk sample. Children (N = 91) who demonstrated perceptual delays and inadequate preacademic reading skills were rated by their teachers as having significantly more behavior problems than children (N = 218) who were negative for these two signs. The results suggest that some children with perceptual problems demonstrate multiple behavior problems prior to experiencing reading failure.

Child Behavior Disorders↗
PubMed1989

[Opinion: informed consent and mental capacity in clinical psychiatric practice (a Quebec perspective)].

This paper on informed consent and psychiatry, asks the fundamental question if informed consent doctrine applies or not to psychiatric practice. In a dialectic between systems of thought in psychiatry and law, the author stresses the importance of particular clinical situations which can be addressed or not in terms of application of informed consent doctrine. The purpose of the paper is not to give a final answer but to bring questions and stimulate thought.

Humans↗
PubMed1988

Facilitation of brain stimulation reward by delta 9-tetrahydrocannabinol.

The present experiment explored whether delta 9-tetrahydrocannabinol (delta 9-THC), the psychoactive ingredient in marijuana, shares with other drugs of abuse the ability to facilitate brain stimulation reward acutely, as measured by electrical intracranial self-stimulation (ICSS). Laboratory rats were implanted with stimulation electrodes in the medial forebrain bundle, and trained to stable performance on a self-titrating threshold ICSS paradigm. delta 9-THC, at a dose believed pharmacologically relevant to moderate human use of marijuana, acutely lowered ICSS thresholds, suggesting that marijuana acts on similar CNS hedonic systems to most other drugs of abuse.

Animals↗
PubMed1987

Ageing and isokinetic plantar flexion.

Isokinetic torques (Cybex II) of the plantar flexors in 25 healthy men were compared at 5 angular velocities (30, 60, 90, 120 and 180 degrees X s-1). The purposes were to compare plantar flexion torques in young and old subjects, and to determine whether the expected decrease was significantly associated with age, physical activity, or aerobic fitness. Four groups were studied: young (21.7 +/- 2.0 years) and older (63.3 +/- 2.8 years), active and sedentary. Measurements of height, weight, % body fat, VO2max, and daily leisure energy expenditure (questionnaire) were determined for each subject. Statistical measures of analysis of variance were used to determine significant differences among groups; product moment correlation and stepwise regression analysis were used to describe the degree of association between the dependent variable of plantar flexion torque and the independent variables at each velocity. A decline in torque was observed as the isokinetic velocity of angular motion increased. Age alone was a significant determinant of plantar flexion torque, whereas at the slowest speed, when VO2max was used as an explanatory variable, age was not a significant determinant of torque. At 30 degrees X s-1 47% of the variance in torque was explained by VO2max while at 180 degrees X s-1 49% of the variance was explained by age.

Adult↗
PubMed1987

Atenolol for ventricular ectopy: a dose-response study.

The antiarrhythmic efficacy, safety, and tolerance of atenolol was evaluated in 32 patients with an average of at least 60 ventricular ectopic depolarizations/hr. Patients received, single-blind, the following treatments for 2 weeks each: placebo and atenolol, 50, 100, and 200 mg daily. A 24-hour ambulatory ECG recording was obtained each week. Reduction in ventricular ectopic frequency by at least 75% occurred in six of 32 patients receiving 50 mg daily, five of 30 patients receiving 100 mg daily, and three of 21 patients receiving 200 mg daily (P = not significant for any paired dose comparison). No patient who failed to respond to a lower dose responded to 200 mg daily. The frequency of ventricular tachycardia was reduced by at least 75% in eight of 17 patients receiving 50 mg daily, seven of 16 patients receiving 100 mg daily, and eight of 11 receiving 200 mg daily (P = not significant for any paired dose comparison). Atenolol was discontinued because of adverse effects in 12 patients. The results indicate that atenolol is more effective in suppressing ventricular tachycardia than in suppressing overall ventricular ectopy.

Adult↗
PubMed1986

C-terminal peptides of rhodopsin. Determination of the optimum sequence for recognition of retinal transducin.

In vertebrate retinal rod outer segments, transducin, a guanine-nucleotide-binding protein, mediates signal coupling between rhodopsin and cyclic GMP phosphodiesterase. Whereas the T alpha subunit (39 kDa) of transducin binds guanine nucleotides and is the activator of the phosphodiesterase, the T beta gamma subunits (35 and 10 kDa) may function to physically link T alpha with photolysed rhodopsin. We have previously reported that a site of binding of transducin is on the C-terminus of bovine rhodopsin. By using competition with synthetic peptides, the recognition region was localized to bovine opsin amino acid residues 317-339. Further studies are detailed which determine the boundaries of this binding site on rhodopsin, as well as some of the critical amino acids needed for transducin binding. These results suggest that the serine and threonine residues in the rhodopsin C-terminal peptides Rhod-1 and Rhod-3 are critical for reconstitution of transducin GTPase activity.

Amino Acid Sequence↗
PubMed1985

Regulation of retinal transducin by C-terminal peptides of rhodopsin.

Transducin is a multi-subunit guanine-nucleotide-binding protein that mediates signal coupling between rhodopsin and cyclic GMP phosphodiesterase in retinal rod outer segments. Whereas the T alpha subunit of transducin binds guanine nucleotides and is the activator of the phosphodiesterase, the T beta gamma subunit may function to link physically T alpha with photolysed rhodopsin. In order to determine the binding sites of rhodopsin to transducin, we have synthesized eight peptides (Rhod-1 etc.) that correspond to the C-terminal regions of rhodopsin and to several external and one internal loop region. These peptides were tested for their inhibition of restored GTPase activity of purified transducin reconstituted into depleted rod-outer-segment disc membranes. A marked inhibition of GTPase activity was observed when transducin was pre-incubated with peptides Rhod-1, Rhod-2 and Rhod-3. These peptides correspond to opsin amino acid residues 332-339, 324-331 and 317-321 respectively. Peptides corresponding to the three external loop regions or to the C-terminal residues 341-348 did not inhibit reconsituted GTPase activity. Likewise, Rhod-8, a peptide corresponding to an internal loop region of rhodopsin, did not inhibit GTPase activity. These findings support the concept that these specific regions of the C-terminus of rhodopsin serve as recognition sites for transducin.

Animals↗
PubMed1985

Psychological normality and abnormality in persistent headache patients.

One hundred and three patients referred to a neurological outpatient clinic were examined to assess the relationship between persistent headache, not due to significant physical illness, and emotional disturbance. Overall, the patients showed slightly more evidence of emotional disturbance than a general practice population but less than psychiatric outpatients. Thus, with cut-off points of 4/5 and 9/10 on the General Health Questionnaire (GHQ 28) the whole group had 52% or 20% of psychiatric 'cases' respectively. On the Crown-Crisp Experiential Index the 70 females had mean total scores of 37.19 +/- 11.11 and the 33 males had scores of 31.79 +/- 11.36. In addition the childhood experiences measured by the Parental Bonding Instrument appeared to be normal. Seven patients had significant depressive illness, according to the Levine-Pilowsky Depression Questionnaire. Statistically significant differences in psychological state did not emerge between the diagnoses of cluster headache, classical migraine, common migraine, tension headache or combined headache. However, negative correlations were found between the duration of illness and measures of anxiety. It is concluded that although the emotional state contributes to the development of pain and headache in some patients, there are others in whom comparable headaches are unlikely to be due to emotional factors. Selection effects are held to be important and some of the emotional changes will vary at different phases of a chronic disorder. A new symptom may initially cause anxiety but when a condition persists some patients will be increasingly concerned or depressed whilst others develop tolerance for the situation.

Adolescent↗
PubMed1985

An open multicentre study of the treatment of florid schizophrenia with remoxipride.

Remoxipride, a novel substituted benzamide, was given for 4 weeks to 18 florid schizophrenics in an open study. The mental state of the majority improved as measured by the Brief Psychiatric Rating Scale. Remoxipride itself did not appear to cause troublesome extrapyramidal effects. There were no significant adverse effects on the cardiovascular system and no significant abnormalities in laboratory tests. These results suggest that remoxipride has antipsychotic effects, and that this should be tested in controlled clinical trials.

Adolescent↗
PubMed1985

[Right to refuse treatment by the involuntary patient: medico-legal considerations].

Forensic topics are discussed in relation to the right to refuse treatment among involuntary hospitalized patients. A clinical case is reported emphasizing the medical and legal dilemmas which the psychiatrist has to cope with. Different legal procedures are examined and their deficiencies discussed; the right to refuse treatment is discussed with reference to recent cases heard in the U.S., The Charter of Rights of the Canadian Constitution 1981 and the "Charte des droits de la personne du Québec". The recommended solution in cases of treatment refusal among involuntary patients centers on the judiciary determination of incompetency of such patients.

Canada↗