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Biomedical subjects

G Mercer

Publications and source records attributed to G Mercer.

At least 19 recordsLinked to original sources
PubMed2001

Acute tryptophan depletion in schizophrenia.

BACKGROUND: Brain 5-hydroxytryptamine (5-HT) function is implicated in the pathophysiology of schizophrenia and the action of new generation antipsychotic drugs. By the method of acute tryptophan depletion (ATD) 5-HT can be selectively manipulated. The aim of this study was to examine the effects of ATD on symptoms, mood and cognition in schizophrenic patients. METHODS: Twenty-eight schizophrenic patients participated in a within subject, double-blind, placebo-controlled counterbalanced cross-over study. Patients with a concurrent DSM-IV axis I diagnosis were excluded. Symptoms, mood and cognitive function were evaluated following ATD or ingestion of a control drink. RESULTS: The depleting drink significantly reduced plasma total and free tryptophan. Tryptophan/LNAA ratios did not alter with the administration of the control drink, but differed significantly with ATD; however there was no significant change in tyrosine/LNAA ratio. ATD led to impairment in executive function that was dependent upon the order of administration. Tests of sustained attention, speed of processing, and everyday memory were not affected. No effects were observed on subjective mood ratings, movement disorders or PANSS scores. CONCLUSIONS: Acute tryptophan depletion selectively alters cognition in schizophrenia, but has no effect on symptoms, mood ratings or movement disorders.

Administration, Oral↗
PubMed2000

Seasonality of eating pathology on the eating attitudes test in a nonclinical population.

OBJECTIVE: To determine whether there are seasonal fluctuations in eating pathology in a nonclinical population. METHOD: The Eating Attitudes Test (EAT) was completed by 322 subjects during winter and again during summer. Summer and winter responses were compared to investigate differences in EAT total and subscale scores and for individual EAT items. Numbers of subjects fluctuating across the seasons by more than 2 SDs of the cohort's scores were identified. RESULTS: The cohort showed no significant seasonal change on EAT-40 totals, EAT-26 totals, or within the EAT subscales. There were significant (p <.025) seasonal fluctuations on four of the EAT-40 questions. For individual respondents, there was no greater likelihood of scoring significantly higher in the winter than in the summer. DISCUSSION: Clinically significant seasonal fluctuations in eating pathology on the EAT did not occur in this nonclinical population. It is debatable whether items within the EAT which show significant seasonal fluctuations should be retained or discarded.

Adult↗
PubMed2000

Developing a tool to measure holistic practice: a missing dimension in outcomes measurement within complementary therapies.

Despite the wide and continuing debate over the relevance of particular research methods to evaluate complementary therapies, less attention has been given to what outcome criteria and measures to use and/or whether these have a sufficient breadth in perspective. While complementary and alternative medicine researchers have paid heed to the importance of measuring the subjective experience of therapy users, they have left unmeasured the notion of holism, in particular, the measurement of the effect of the interaction between therapist and therapy user, and its underlying philosophy of health and healing. This paper reports on an exploratory, qualitative study aimed at developing a measure of holism and holistic practice. It draws out some key features requiring measurement and provides insight into the emerging measure. Further development work is needed before the measure can be used within research or routine practice.

Complementary Therapies↗
PubMed1997

A study of enhanced management in patients with treatment-resistant schizophrenia.

The clinical efficacy of two intensive treatment packages (one including the new antipsychotic risperidone and the other not doing so) was compared with that of standard management in 43 patients with long-standing treatment-resistant schizophrenia. Significant differences between the groups in terms of total positive or total negative symptoms were not demonstrated, but the pattern of change between the treatment groups differed, so that benefit in positive symptomatology was seen in both intensive treatment groups and in negative symptomatology in the intensive treatment/risperidone group and the standard group. Changes in general psychopathology were most marked in the risperidone group and were compatible with a relatively non-sedative profile. Using the Disability Assessment Schedule, substantial significant advantages for the intensive treatment groups were found.

Adult↗
PubMed1997

The use of videotaped assessment in relation to a study of enhanced management in treatment-resistant schizophrenia.

Videotaped assessments of standardized interviews were used to ensure blindness in relation to a clinical trial of multifaceted programmes of management in patients with treatment-resistant schizophrenia. The technique, although laborious, was feasible in all patients studied and offered advantages in relation not only to blindness but also to assessing the nature of psychopathological changes in patients with schizophrenic deficit syndrome of severe degree. The method is likely to be useful in further studies assessing the possible advantages of newer antipsychotic drugs.

Adult↗
PubMed1996

Seasonal affective disorder among psychiatric nurses in Aberdeen.

The Seasonal Pattern Assessment Questionnaire was posted to psychiatric nurses in Aberdeen, and 443 (73% of eligible subjects) responded. The rate of Seasonal Affective Disorder (SAD) was 2.9% and for subsyndromal SAD (S-SAD) was 9.5%. When rates were age and sex adjusted to the Aberdeen population aged 15 to 64, this yielded a prevalence of 1.9% for SAD and 7.2% for S-SAD. As in other studies, there was a preponderance of young female sufferers, but being married appeared to be protective. Comparisons with epidemiological studies elsewhere lead to the conclusion that population rates of winter depression relate to a combination of genetic susceptibility/selection, latitude of residence and geographical mobility.

Adolescent↗
PubMed1996

Brain alcohol detectability increase with repeated administration in humans: a proton spectroscopy study.

Proton MRS was used to detect brain alcohol after repeated alcohol exposure in human subjects. MRS detectability measurements were made after administration of an alcoholic drink (0.6 g/kg alcohol) and after an identical drink administrated 6 h later. Between-drink differences in the methyl proton triplet resonance of ethyl alcohol were assessed at statistically equivalent and near-peak blood alcohol concentrations (reflecting brain alcohol concentrations) and statistically equivalent internal standard N-acetyl resonance areas after Drinks 1 and 2, respectively. Brain alcohol detectability was not altered in TE 30-ms spectra but was increased in all five subjects after Drink 2 by an average of 70% in TE 270-ms spectra (p < 0.01). This was accompanied by significant between-drink differences in subjective ratings of alcohol's effects, suggestive of induction of acute alcohol tolerance. These findings suggest increased brain alcohol detectability in TE 270-ms spectra after repeated alcohol exposure that may reflect acute alcohol tolerance.

Adult↗
PubMed1996

Effects of cocaine on pulsatile activity of hypothalamic-pituitary-adrenal axis in male rhesus monkeys: neuroendocrine and behavioral correlates.

Cocaine stimulates the hypothalamic-pituitary-adrenal (HPA) axis in rodents and in humans. This study examined the acute effects of cocaine (0.4 and 0.8 mg/kg) and saline placebo on pulsatile adrenocorticotropic hormone (ACTH) and cortisol release in seven male rhesus monkeys. Pulsatile ACTH and cortisol release were evaluated with an intensive (2-min) venous blood sampling procedure and cluster analysis. In addition, the behavioral responses to cocaine were analyzed to assess the relationship between HPA axis activation and behavior. Although analysis of group data revealed significant (P < .05) increases in pulse amplitude and incremental peak height of ACTH and cortisol release after cocaine (0.8 mg/kg) administration, examination of individual data indicated that this effect was not consistent across all monkeys. Cocaine (0.8 mg/kg) increased ACTH plasma levels within 4.7 +/- 1.3 min (P < .05) and amplitude-related characteristics (P < .05) of pulsatile ACTH and cortisol release only in those animals that subsequently showed behavioral stimulation (high responders: n = 3). The frequency of pulsatile ACTH and cortisol remained unchanged by cocaine. Cocaine (0.8 mg/kg) decreased the mean amplitude of ACTH peaks with no changes in pulsatile cortisol release in the four monkeys that showed no behavioral stimulation (low responders). These differences in pulsatile ACTH and cortisol release patterns after cocaine could not explained by different plasma cocaine levels. Peak plasma cocaine levels averaged 63.1 +/- 13.4 and 78.0 +/- 21.4 ng/ml within 2 min after lower dose and 183.3 +/- 52.3 and 204.3 +/- 50.8 ng/ml after higher dose of cocaine in high- and low responder groups, respectively (P > .05; N.S.). Base-line cortisol, but not ACTH, levels were higher (P < .05) in low responders before administration of 0.8 mg/kg of cocaine. Peak and valley characteristics of base-line cortisol release were higher in low responders than in high responders and an inverse relationship was found between basal cortisol levels and postcocaine ACTH release and behavior. In summary, cocaine stimulated the pulsatile ACTH and cortisol release by increasing the amplitude of secretory episodes in behaviorally responsive monkeys.

Adrenocorticotropic Hormone↗
PubMed1995

Organochlorines in Pleuronectidae: comparison between three tissues of three species inhabiting the Northwest Atlantic.

Muscle, liver, and gonad from three species of flatfish, turbot, American plaice, and yellowtail flounder collected in the Northwest Atlantic were analyzed for a variety of organochlorine contaminants. Female flounder and plaice had lower concentrations of organochlorines than males, in all tissues. Comparing values to those previously obtained for Atlantic cod showed that concentrations in liver, the organ most often used in biomarker studies, followed the order: cod > turbot > plaice > flounder and correlated with lipid content. Muscle concentrations, which are important from a consumers perspective, followed the order: turbot > plaice > flounder > cod and were also correlated with lipids. The concentration of contaminants in gonads, the organ that informs on the future of a species were nearly undetectable. Cluster analyses demonstrated that the environmental behaviour of these contaminants can be subdivided into groups, consistent with their known chemical origin. Of the series of total and specific polychlorinated dibenzo-p-dioxins and furans studied, only tetrachlorodibenzofuran was present in most tissues.

Animals↗
PubMed1995

Schizophrenia, symptomatology and social inference: investigating "theory of mind" in people with schizophrenia.

It has been proposed that certain psychotic symptoms associated with schizophrenia reflect a deficit in the ability to appreciate other people's mental states (Frith, 1992). This notion is tested using a newly devised task examining the capacity to infer intentions behind indirect speech. The findings support the notion that some patients with schizophrenia have difficulties with tasks requiring 'theory of mind' skills and that this deficiency is symptom specific. The findings are discussed with reference to the cognitive skills which may be involved in the performance of tasks requiring social inferences.

Adult↗
PubMed1995

The concordance of pulsatile ultradian release of adrenocorticotropin and cortisol in male rhesus monkeys.

The ultradian release of ACTH and cortisol was investigated in six male rhesus monkeys (Macaca mulatta) with an intensive (2-min) blood-sampling procedure to investigate micropulsatile hormone secretory patterns. A sensitive and specific immunoradiometric assay was used to measure plasma ACTH concentrations. An objective pulse detection algorithm (Cluster) was used to assess the pulsatility of ACTH and cortisol release. The temporally coincident release of ACTH and cortisol was also examined. Venous blood samples were collected (over < 15 s) every 2 min for 120 min beginning at 1300 h. The number of ACTH peaks (3.2 peaks/h), interpulse intervals (19 +/- 2.4 min), and pulse amplitudes (9.7 +/- 1.6 pmol/L) in rhesus monkey were similar to corresponding measures of ACTH release in humans (3.3 peaks/h, 18 +/- 0.8 min, and 4.7 +/- 1.0 pmol/L, respectively). The number of cortisol peaks (2.3 peaks/h), interpulse interval (26 +/- 8.6 min), and other characteristics of pulsatile cortisol release were also determined. There was a 32.4% exact concordance of ACTH with cortisol peaks (11 of 34; P < 0.001). Fifty-six percent of ACTH peaks (19 of 34) were followed by a cortisol peak within 10 min (P < 0.02). There was a significant correlation between the ACTH and coincident cortisol pulse amplitudes (P < 0.0001). The amplitudes of ACTH peaks coincident with cortisol peaks at 0 min time lag were significantly higher than ACTH peaks not temporally coupled with cortisol peaks. Our data indicate that 1) high frequency, low amplitude micropulsatile ACTH secretion in rhesus monkeys is very similar to the high frequency ACTH rhythm in humans; 2) temporally concordant ACTH and cortisol release episodes may be amplitude coupled; and 3) an adequate incremental ACTH pulse amplitude may elicit a concurrent cortisol release episode from the adrenal cortex. These data suggest that the rhesus monkey is a potentially useful model for the study of neuroendocrine control of ACTH release.

Activity Cycles↗
PubMed1994

Prediction of outcome following a first episode of schizophrenia. A follow-up study of Northwick Park first episode study subjects.

BACKGROUND: Although previous studies have attempted to identify predictors of outcome in schizophrenia, few have prospectively studied first episode patients for an adequate follow-up period. METHOD: The psychopathological predictors of outcome were investigated in a subgroup of 51 subjects, originally included in the Northwick Park study of first episode schizophrenia who were followed up 7.3 years (s.d. 1.1, range 5.3-10.3) after first admission in the Harrow study. Forty-four subjects (24 men, 20 women) were traced. Outcome measures were time to first readmission, occupational level and total duration of hospital admission at five years after first admission. RESULTS: A survival analysis of time to first relapse revealed that the presence of subjective feelings of depression (CATEGO syndrome SD) during the first admission was associated with early relapse while the presence of depressive delusions (CATEGO syndrome DD) and higher educational attainment protected against early relapse. Total duration of hospitalisation at five years after first onset was positively associated with the presence of CATEGO syndromes SD and OD (biological features of depression) and negatively associated with female sex. Poor occupational outcome was not significantly associated with any psychopathological predictors. CONCLUSIONS: Our findings challenge the conventional view that symptoms of depression are associated with better outcome in schizophrenia.

Adolescent↗
PubMed1993

Pituitary volume in men with concurrent heroin and cocaine dependence.

Pituitary gland volume was measured in 16 men between the ages of 26-33 with magnetic resonance imaging. Eight male patients had a Diagnostic and Statistical Manual III-Revised, American Psychiatric Association Axis I diagnosis of concurrent opioid and cocaine dependence. The average duration of opioid and cocaine abuse was 7.8 +/- 2.0 and 6.9 +/- 1.4 yr, respectively. All patients were in good physical health as determined by physical examination, blood chemistry, hemogram and hormone analysis, and all tested negatively for the HIV antibody. No patient had any other Diagnostic and Statistical Manual III-Revised Axis I diagnosis or neurological disorder. Eight healthy males served as age-matched control subjects. None of the control subjects had any past or current history of substance abuse or any clinical indication for magnetic resonance imaging. Opioid and cocaine dependent men had significantly larger pituitary gland volumes (730.0 +/- 24.4 mm3) than control subjects (540.0 +/- 26.6 mm3) (P < 0.01). The significant increase in pituitary gland volume in men who abuse opiates and cocaine may be antecedent to detection of abnormal anterior pituitary hormone function.

Adult↗
PubMed1991

Fatal embolization of intestinal contents through a duodenocaval fistula.

Embolization of intestinal contents to the lung is an exceedingly rare event, which to our knowledge, has never been reported as a cause of death. Equally rare is duodenocaval fistula resulting from a penetrating duodenal peptic ulcer. We present the case of a 51-year-old man whose duodenal ulcer led to a fistulous tract with the inferior vena cava and subsequently to progressive pulmonary embolization of intestinal contents, ultimately resulting in death from respiratory failure.

Duodenal Diseases↗
PubMed1988

Major histocompatibility complex (MHC) factors predisposing to and protecting against Graves' eye disease.

We investigated the influence of gene mapping within the major histocompatibility complex on the susceptibility to Graves' eye disease. We studied 133 randomly selected patients with Graves' disease, many of whom had eye disease. HLA B8 and DR3 carried the greatest risk for disease but the difference between the two patient groups was not statistically significant. An earlier finding that Hungarian patients with a subset of B8, (B8 + DR7 +) had a greatly enhanced risk for eye disease was confirmed in Newfoundland patients. HLA B8 and DR7 are probably carried on different homologous chromosomes and their interaction enhances eye disease. HLA-DR4 was negatively correlated with eye disease. In particular, a subset of DR4 (B35 + DR4 +) appears to protect against eye disease. We have also derived the haplotypes of 22 probands, half of whom had eye disease. The haplotype data emphasized the high frequency of HLA A1 B8 DR3 C4A*QO and C4B*1 in both patient groups, 15% of the haplotypes in the group with eye disease and 25% in that without eye disease. Forty-one percent of haplotypes in the eye disease group and 32% in the no eye disease group were either C4A*QO or C4B*QO. In one proband with eye disease B8 and DR7 were carried on separate chromosomes. The phenotype DR4, C4A*3 C4B*1 was found in 3/20 haplotypes of patients without eye disease but in 0/20 of patients with eye disease. This finding is in keeping with the increased frequency of the DR4 C4A*3 C4B*1 in the patient group with no eye disease when 94 patients were phenotyped.(ABSTRACT TRUNCATED AT 250 WORDS)

Disease Susceptibility↗