Biomedical subjects

G D Burrows

Publications and source records attributed to G D Burrows.

At least 91 records · Page 5Linked to original sources

PubMed1989

Quantal melatonin suppression by exposure to low intensity light in man.

Plasma melatonin concentrations were examined following three relatively low intensities of artificial light. Six normal, healthy control subjects were all exposed to (a) 200 lux, (b) 400 lux and (c) 600 lux for a three hour duration from midnight to 0300 h. Blood was also collected on a control night where light intensity was less than 10 lux throughout. Significant suppression of melatonin was observed following light of 400 lux and 600 lux intensity when compared to the control night (p less than 0.05; Mann-Whitney U-test). 200 lux light did not produce a statistically significant melatonin suppression when compared with control samples. Each light intensity produced its own individual maximal melatonin suppression by one hour of exposure. Increased duration of exposure to the light had no further influence on melatonin plasma concentrations. These data confirm a dose response relationship between light and melatonin suppression, and indicate that there is no reciprocal relationship between the effects of light intensity and the duration of exposure on maximal melatonin suppression in man.

Adult↗

PubMed1989

Platelet serotonin uptake in panic disorder patients: a replication study.

Platelet serotonin uptake was measured in 29 patients with DSM-III panic disorder or agoraphobia with panic attacks and compared to values obtained in 23 controls. Both the affinity constant (Km) and the maximal rate of uptake (Vmax) were determined in a buffered medium using 14C-serotonin. Patients and controls did not differ significantly with respect to age or Km values. A statistically significant difference was observed for Vmax (mean +/- SD = 65 +/- 22 pmol/10(8) platelet/min in patients vs. 44 +/- 13 pmol/10(8) platelets/min in controls). This finding suggests an overactivity of peripheral serotonergic function in panic disorder, which may also imply a similar dysfunction centrally.

Adolescent↗

PubMed1989

Human melatonin response to light at different times of the night.

Normal control subjects were examined on three separate occasions with light of sufficient intensity to suppress nocturnal plasma melatonin concentrations. One hour of light was given at each of the following times: (a) 2100-2200h; (b) midnight to 0100h; (c) 0400-0500h. Melatonin synthesis was just becoming apparent at 2100h. There was significant suppression of melatonin by light when given at midnight-0100h and 0400-0500h, but not when light was given at 2100-2200h. In each case following light, melatonin synthesis was shown to resume, even after light applied in the second half of the dark period (0400-0500h). A second experiment was undertaken to examine a possible "rebound" in melatonin levels following light given at 2100-2200h. Six further control subjects were exposed to light at this time, and plasma melatonin levels were measured until 0400h. No rebound in melatonin concentrations was observed. These results are compared with other studies of melatonin response to evening light exposure.

Adult↗

PubMed1989

Serotonin in panic disorder: platelet uptake and concentration.

Platelet serotonin uptake and platelet serotonin concentrations were measured in 17 patients (5 males, 12 females) with panic attacks and 15 controls (8 males, 7 females). Higher Vmax values were found in the patient group compared with controls (65 +/- 7 vs. 47 +/- 3 pmol/10(8) platelets/min; p less than 0.05) while the affinity constant Km was not significantly different (0.6 +/- 0.1 vs. 0.5 +/- 0.1 microM). Platelet serotonin concentrations were not significantly different between the two groups (38 +/- 4 vs. 41 +/- 4 ng/10(8) platelets). These results confirm our earlier finding of increased serotonin uptake in patients with panic attacks and suggest that platelet serotonin levels are normal.

Adult↗

PubMed1989

A short term open clinical trial of clobazam in the treatment of patients with panic attacks.

Clobazam, a 1-5 benzodiazepine with anxiolytic properties, was evaluated in the treatment of patients with DSM-III panic disorder or agoraphobia with panic attacks. In this open clinical trial, 10 of the 15 patients completed 8 weeks of treatment. Six of the 10 completers (60%) were responders (75% reduction in the number of panic attacks from baseline) at the end of 8 weeks. Of the responders so defined, 5 of the 6 were panic free. At the end of week 8 the average dose for the responders to medication was 50 +/- 17 (S.D.) mg per day. Clobazam was well tolerated at the doses used with the few side-effects recorded as mild to moderate. The study suggests that further placebo-controlled studies are warranted to evaluate clobazam's potential antipanic effect.

Adolescent↗

PubMed1989

Lectures and skills workshops as teaching formats in a history-taking skills course for medical students.

The consulting skills acquired by medical students during their training are an important determinant of their ability to conduct adequate and efficient clinical interviews. These skills comprise: the acquisition of medical knowledge and the ability to apply this; and communication skills required to obtain full, accurate clinical histories from patients and to be able to give to patients the information they need to comply with prescribed regimens. Until recently, consulting skills training has certainly not had a high profile in medical curricula, despite evidence that students do not gain sufficient expertise during their medical training. A history-taking skills course within the Austin Hospital Clinical School, utilizing mass lecture and small-group skills workshops is described. Independent evaluation of students' videotaped interviews with patients, completed before training, after mass lectures and following small-group workshops, showed that students trained in consulting skills demonstrated significant improvements in interview skills and techniques, compared with a similar group of students for whom training followed the more traditional model. Whilst there were some improvements after mass lectures, most significant gains in history-taking skills were obtained following skills workshops. Ongoing evaluation of these students will determine if these short-term improvements in consultation skills persist over their clinical training and internship.

Clinical Clerkship↗

PubMed1989

Psychological tests to measure the effects of medical education on students' interpersonal skills.

The consulting skills required of medical students and practitioners have been categorized into a number of specific skills, two of which are: students' ability to empathize with the patient; and ability to decode non-verbal cues given by the patient in the interview. Training programmes to improve students' consulting skills are usually evaluated using analysis of students' actual interview behaviours with patients. Broad psychological and personality tests have also been used to measure changes in students' interviewing skills, but have generally not been successful. The hypothesis is advanced that more specific tests of the skills of interviewing, such as non-verbal sensitivity and empathy, would detect changes in students' ability to display these skills. As part evaluation of a consulting skills training programme, clinical students completed psychological tests of empathy and non-verbal sensitivity. Subsequent comparisons between trained and control student groups revealed no clear pattern in test results. These data suggest that specific psychological tests of empathy and non-verbal sensitivity may be no more effective in detecting changes in students' interpersonal skills than global personality measures.

Clinical Clerkship↗

PubMed1989

Human melatonin suppression by light is intensity dependent.

Five intensities of artificial light were examined for the effect on nocturnal melatonin concentrations. Maximum suppression of melatonin following 1 hr of light at midnight was 71%, 67%, 44%, 38%, and 16% with intensities of 3,000, 1,000, 500, 350, and 200 lux (lx), respectively. In contrast to some previous reports, light of 1,000 lx intensity was sufficient to suppress melatonin to near daytime levels, and intensities down to 350 lx were shown to significantly suppress nocturnal melatonin levels below prelight values. On the basis of these data, it is suggested that when examining the melatonin sensitivity of patient groups (such as bipolar affective disorders) to artificial light, an appropriate light intensity should be established in each laboratory. Light of less intensity (e.g., 200-350 lx) may be more suitable to dichotomize patient groups from control subjects.

Adult↗

PubMed1989

Depression following spinal cord injury. A prospective in-patient study.

In a systematic prospective study of 71 patients with acute spinal cord injury carried out in the acute and rehabilitation phases of treatment, 14 patients meeting the DSM-III criteria for major depressive disorder were identified. A further 13 patients had transient periods of depressed mood, while the majority of patients showed no clear evidence of depression. The BDI was found to be valid in this group of patients.

Adjustment Disorders↗

PubMed1989

Ethical issues and acquired immunodeficiency syndrome (AIDS).

Acquired Immunodeficiency Syndrome (AIDS) has received much publicity and medical attention. Interest has focused on education, epidemiology, treatment and prevention of the syndrome. This paper raises other issues for consideration, including problems associated with HIV testing, confidentiality, informed consent and the dilemmas facing those involved in the treatment of patients suffering from HIV infection.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Treatment of seasonal affective disorder with light: preliminary Australian experience.

Six patients with a history of Seasonal Affective Disorder (SAD) were treated with bright artificial light. Patients presented with at least two consecutive years of loss of energy, difficulty in working, loss of interest in activities, difficulty in concentrating, increased somnolence, over-eating (carbohydrate craving) and depressed mood. All received seven consecutive days of full-spectrum bright light with an intensity greater than 2,500 lux at a distance of three feet. Evening exposure for two hours resulted in significant clinical improvement. The main improvements were a return to normal sleeping patterns, a reduction in eating habits, improved energy level, a desire to continue with interests and activities and an improvement in mood. Possible mechanisms for the clinical effects of bright light treatment are discussed.

Australia↗

PubMed1989

Stress, marital separation and divorce.

Marital separation and divorce are common and major causes of stress in our society. The general practitioner should keep marital disharmony and pending separation in mind when one or both partners present with recurring medical problems that are often minor in nature. It is important for the GP to become involved with caring, support and appropriate counselling of the partners, their children and other family members. Any homicidal or suicidal threats should be taken very seriously.

Divorce↗

PubMed1989

Serotonin and panic disorders: a review of clinical studies.

The revision of psychiatric diagnostic criteria by DSM-III has emphasised the central importance of panic attacks for the diagnosis of anxiety disorders. Since the introduction of this classification, there has been a re-evaluation of the role of major neurotransmitters as causal factors in anxiety disorders. The evidence for serotonergic hyperactivity in panic disorders is supported by the efficacy of specific serotonin reuptake blockers and 5HT2 receptor antagonists in the treatment of the condition. In addition neuroanatomical studies and positron-emission transaxial tomographic scanning are also consistent with a key role for serotonin in panic disorder. Clinical evidence of serotonin dysfunction has been sought using the blood platelet, a putative model of central serotonergic neurons. Studies of 3H-imipramine binding in platelets are equivocal, but most find no difference between patients and controls. On the other hand platelet serotonin uptake is significantly elevated in panic patients compared to controls. The reasons for the difference between two reputed markers of presynaptic serotonergic function is explored. The prolactin response to intravenous tryptophan administration is regarded as a functional correlate of central serotonergic neurons. Panic disorder patients and controls were not different in one study using this test. Serotonin concentrations in panic patients may be abnormal compared with appropriate controls. Replication of these preliminary data are necessary to confirm serotonergic dysfunction and to elucidate the interaction with other neurotransmitters, with clear implications for pharmacotherapy.

Fear↗

PubMed1989

Monoamine oxidase, monoamine oxidase inhibitors, and panic disorder.

Monoamine oxidase inhibitors are effective in the treatment of panic attacks. Phenelzine has been used most often with good effect and is regarded by some as the treatment of first choice for panic disorders. Nevertheless the potential dangers of the use of non-specific MAOIs are well recognised and there is a need for safer drugs. The efficacy of specific MAO inhibitors such as moclobemide (MAO-A) and deprenyl (MAO-B) are yet to be investigated. The activity of the enzyme MAO in blood platelet (MAO-B) has been extensively studied. A review of early findings of elevated MAO activity suggests a number of reasons why the data should be interpreted with caution. Recent studies do not support the earlier findings and suggest no difference in platelet MAO activity between patients and controls. Similarly studies of the endogenous MAO inhibitor, tribulin, suggest that the output in panic disorder patients is similar to that of controls. Studies of the effectiveness of specific MAOIs in panic attacks are warranted as are further studies of the biochemical aetiology.

Fear↗

PubMed1989

The biology of panic-genetic evidence.

Family aggregations for panic disorder as defined by the American Psychiatric Association's DSM-III classification were examined at the Austin Hospital in Victoria, Australia, covering 636 individuals. The results were consistent with the common genetic relatedness of parents to offspring and of sibling pairs, but also consistent with other factors common to the family. The family data alone were not sufficient to draw conclusions about the cause of aggregation.

Adolescent↗

PubMed1989

Plasma melatonin levels in affective states.

Melatonin is a major endocrine product of the pineal gland. It is produced at night when noradrenaline acts on beta-adrenergic receptors to stimulate enzymes which catalyse the formation of melatonin from serotonin. It is believed by some that nocturnal melatonin levels reflect beta-receptor function. The melatonin rhythm is also thought to be an indication of circadian rhythmicity. The nocturnal production of melatonin was studied in patients with depression and panic disorder and in control subjects. Midnight concentrations of melatonin in eleven depressed patients were significantly lower than 18 control subjects (27.1 +/- 5.1 pg/ml compared with 51.6 +/- 4.1 pg/ml; p less than 0.02, t-test). These data support previous reports of reduced melatonin synthesis in depressive illness. In the first report of patients with panic disorders, significantly lower midnight levels of melatonin were found compared with controls (28.4 +/- 6.4 pg/ml versus 51.6 +/- 4.1 pg/ml, p less than 0.02, t-test). In subsequent investigations this finding was confirmed, measuring melatonin levels over the initial phase of synthesis (i.e. 20h00 to 24h00). In these samples the melatonin rhythm also seemed to be delayed. These findings are discussed in terms of beta-receptor function and circadian rhythm alterations in affective disorders.

Adolescent↗

PubMed1988

Alprazolam in panic disorder and agoraphobia: results from a multicenter trial. I. Efficacy in short-term treatment.

Following promising preliminary evidence, the benzodiazepine-derivative alprazolam was studied in a large, placebo-controlled, eight-week, flexible-dose trial in patients with agoraphobia with panic attacks and panic disorder. Of 526 patients, 481 completed three weeks of treatment; however, significantly more placebo (102/234) than alprazolam (21/247) recipients subsequently dropped out of the trial, primarily citing ineffectiveness (of placebo) as the reason. Alprazolam was found to be effective and well tolerated. There were significant alprazolam-placebo differences in improvement for (1) spontaneous and situational panic attacks, (2) phobic fears, (3) avoidance behavior, (4) anxiety, and (5) secondary disability, all significant by the end of week 1. At the primary comparison point (week 4), 82% of the patients receiving alprazolam were rated moderately improved or better vs 43% of the placebo group. At that point, 50% of the alprazolam recipients vs 28% of placebo recipients were free of panic attacks.

Adolescent↗

PubMed1988

Alprazolam in panic disorder and agoraphobia: results from a multicenter trial. II. Patient acceptance, side effects, and safety.

In a multicenter placebo-controlled study, the safety, side effects, and patient acceptance of alprazolam for the treatment of panic disorder and agoraphobia were examined. A total of 525 patients meeting DSM-III criteria for agoraphobia with panic attacks or panic disorder were randomly assigned to receive alprazolam or placebo, which they took for eight weeks. The mean daily dose at the end of the study was 5.7 mg of alprazolam or 7.5 capsules of placebo daily. Potentially serious reactions to alprazolam occurred in ten of 263 subjects who received the drug. These included acute intoxication (three), hepatitis (two), mania (two), amnesia (one), aggressive behavior (one), and depression (one). Treatment-related side effects that were worse in patients taking alprazolam than in those taking placebo included sedation, fatigue, ataxia, slurred speech, and amnesia. Sedation was the most frequent but tended to subside with dose reduction or continued administration of the drug. Patient acceptance of alprazolam, as measured by the rate of completion for study participants, was high. Eighty-four percent of patients receiving active drug completed the study compared with 50% receiving placebo.

Adult↗