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Biomedical subjects

H Agren

Publications and source records attributed to H Agren.

At least 73 records · Page 4Linked to original sources
PubMed1992

Operators and scales: diagnostic and rating issues in psychiatric PET research.

In psychiatric research that for various reasons has to restrict itself to a limited number of subjects, such as studies involving expensive positron emission tomography techniques, issues concerning the parsimonious description of patients gain in importance. The number of descriptive variables must be optimally small. This paper offers a conceptual back-ground for the choice of operators in operational diagnostic systems designed to delimit pathological types, and of rating scales designed to measure syndromal severity in a dimensional way. A practical suggestion in five tenets for the organization of clinical research of this kind is presented.

Humans↗
PubMed1991

Brain kinetics of L-[beta-11C]dopa in humans studied by positron emission tomography.

The in vivo dopamine precursor L-3,4-dihydroxyphenylalanine (L-DOPA) labelled with 11C in the beta position has been used for positron emission tomography studies of L-DOPA utilization in the brain. The brain uptake and kinetics of L-[11C]DOPA-derived radioactivity were studied in healthy male volunteers, and the specific utilization, i.e. decarboxylation rate of L-[11C]DOPA in different brain areas, was quantified using a brain region devoid of specific L-[11C]DOPA utilization as reference. Total uptake of L-[11C]DOPA-derived radioactivity measured in the brain varied two- to three-fold between subjects, with highest radioactivity in the striatal region. Specific utilization of L-[11C]DOPA radioactivity in the striatal region and in the prefrontal cortex varied twofold between subjects. No specific utilization was observed in other regions of the brain. The uptake of radioactivity in the brain increased dose-dependently with the simultaneous administration of unlabelled L-DOPA up to 10 mg. On the other hand, a decrease in brain radioactivity uptake was measured after pretreatment with 1 mg/kg oral L-DOPA, indicating competition for transport across the blood-brain barrier. Benserazide 0.5 mg/kg orally increased somewhat the radioactivity uptake to the brain. None of these pharmacological perturbations demonstrated any clearcut effect on specific utilization of L-[11C]DOPA. Thus, 11C-labelled L-DOPA is introduced as an alternative to the well-established L-6-[18F]fluoro-DOPA methodology in clinical studies on brain L-DOPA uptake and dopamine synthesis.

Adult↗
PubMed1991

Cerebrospinal fluid calcium, parathyroid hormone, and monoamine and purine metabolites and the blood-brain barrier function in primary hyperparathyroidism.

Psychiatric disturbances are common in primary hyperparathyroidism (HPT), but their pathogenesis is essentially unknown. This study deals with cerebrospinal fluid (CSF) calcium homeostasis and its connection with parathyroid hormone (PTH), blood-brain barrier (BBB) function, and central monoamine and purine metabolites in patients with primary HPT. In 22 patients with primary HPT (serum calcium 2.85 +/- 0.21 mmol/l), the CSF concentrations of total and ionized calcium were higher (1.21 +/- 0.08 mmol/l, p less than 0.01, and 1.09 +/- 0.05 mmol/l, p less than 0.001, respectively) than in 11 normocalcemic reference subjects. The values correlated with serum calcium concentration (p less than 0.001) and CSF/serum albumin ratio, a measure of BBB permeability. The latter ratio was elevated in one-third of the patients with HPT, indicating BBB damage. CSF immunoreactive intact PTH was higher in the HPT patients than in the reference group (p less than 0.05), and serum and CSF PTH were positively correlated (p less than 0.05). The CSF levels of the monoamine metabolites 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA) were lower, and the level of urate in CSF was higher, in the HPT patients than in the reference subjects, while there were no consistent differences in CSF hypoxanthine or xanthine. CSF 5HIAA correlated inversely with CSF ionized calcium (r = -0.42, p = 0.02). After parathyroid surgery, CSF calcium and urate decreased significantly and CSF monoamine metabolites increased slightly. The decrease in CSF ionized calcium correlated with the alleviation of psychiatric symptoms. The results indicate the importance of increased CSF calcium concentrations in patients with primary HPT and suggest a relation between central calcium regulation and central turnover of monoamines.

Blood-Brain Barrier↗
PubMed1991

Low brain uptake of L-[11C]5-hydroxytryptophan in major depression: a positron emission tomography study on patients and healthy volunteers.

The precursor of serotonin, L-5-hydroxytryptophan (L-5-HTP), was radiolabelled with 11C in the beta-position, yielding [beta-11C]serotonin after decarboxylation, allowing positron emission tomography studies of L-5-HTP uptake across the blood-brain barrier. We studied 8 healthy volunteers and 6 patients with histories of DSM-III major depression, 2 with repeated examinations after clinically successful treatment. We report a significantly lower uptake of [11C]5-HTP across the blood-brain barrier in depressed patients, irrespective of phase of illness. The findings emphasize that serotonin is involved in depressive pathophysiology and support earlier suggestions that the transport of 5-HTP across the blood-brain barrier is compromised in major depression.

5-Hydroxytryptophan↗
PubMed1990

Factors influencing the outcome of thyrostatic drug therapy in Graves' disease.

In patients with Graves' disease, thyrostatic drug treatment may induce definitive remission without the need of more aggressive measures such as surgery or radioiodine. Following drug therapy, however, relapses often occur. In the present study, a multivariate analysis of pretreatment variables was performed, in order to identify individuals running a high risk of an unfavourable outcome of thyrostatic drug therapy. We studied 109 consecutive patients with a mean age of 38 years, range 20-70, over a mean follow-up period of 5.3 years after cessation of therapy. The analysis showed that goitre size, age, thyroid hormone levels, HLA-DR 3 haplotype, and TSH receptor antibody levels were of prognostic significance, whereas HLA-B8 haplotype, a lymphocytic infiltrate at fine needle biopsy, thyroglobulin, and microsomal antibodies had no such value. In particular, patients characterized by young age, large goitre and high hormone values were found to be associated with an unfavourable course.

Adult↗
PubMed1989

Diurnal variation in the concentrations of catecholamines and indoleamines in the median eminence and in the intermediate and posterior lobes of the pituitary gland of the male rat.

Diurnal changes in monoamine concentrations were studied in the median eminence and in the intermediate and posterior lobes of the pituitary gland of the male rat. The concentrations of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), noradrenaline (NA) and dopamine (DA) were analyzed at 7 time points over a 24-h period. Diurnal variation was analyzed by analysis of variance (ANOVA) with time of day as a class variable as well as by 24 h and 12 h cosine curve fittings. There were marked time-dependent changes in the median eminence concentrations of 5-HT (ANOVA: P = 0.0085), 5-HIAA (P = 0.003) and NA (P = 0.0003). Cosine curves with 24-h periods fit the data points with peaks around 13.00 h. DA levels also varied with an apparent 24-h rhythm in the median eminence, but the changes did not reach the level of significance in the ANOVA. In the intermediate lobe of the pituitary gland, the concentrations of DA varied significantly during the course of the 24-h cycle (P = 0.0011) and were well-fitted to a 24-h cosine wave. The 5-HIAA levels also showed marked diurnal changes (P = 0.025) with an evident 12-h rhythm. In contrast, NA and 5-HT concentrations did not appear to vary during the 24-h cycle. In the posterior lobe of the pituitary gland. DA had a 24-h rhythm (P = 0.0005) similar to the intermediate lobe. NA and indoleamine levels did not show any significant variation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Enhancement of dopamine metabolism in rat brain frontal cortex: a common effect of chronically administered antipsychotic drugs.

Administration of 4 antipsychotic drugs, haloperidol, chlorpromazine, thioridazine and clozapine, for 21 days elicited increased dopamine metabolism in frontal cortex of rat brain. Only clozapine failed to decrease the apparent firing rate of dopamine neurons in the striatum, as indexed by [homovanillic acid]/[dopamine]. These data support the hypotheses that frontal cortex dopamine neurons may be a common site for antipsychotic action while decreased release of dopamine in the striatum may be associated with the development of extrapyramidal side effects.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

Psychiatric symptoms and cerebrospinal fluid monoamine metabolites in primary hyperparathyroidism.

This prospective study included 32 patients with primary hyperparathyroidism (HPT). As compared with a healthy reference group, the patients had pronounced psychiatric symptomatology [CPRS score 17.2 +/- 9.0 (SD) versus 4.4 +/- 2.0], which was mainly affective in character. The severity of symptoms was not related to the serum calcium or parathyroid hormone concentrations. The majority of the patients had low CSF concentrations of monoamine metabolites (5-HIAA, HVA, and MHPG) and, in particular, those with the most severe psychiatric symptoms had low values for 5-HIAA. At follow-up, 1 year after parathyroid surgery, the patients displayed a clear improvement in mental health (CPRS score 4.4 +/- 3.0) together with an increase in CSF concentrations of 5-HIAA and HVA. The study demonstrates that significant psychiatric disturbances, which can be improved/normalized by surgery, are common in patients with HPT and are possibly related to changes in the central nervous system turnover of monoamines.

Aged↗
PubMed1988

Creatinine and creatine in CSF: indices of brain energy metabolism in depression. Short note.

In an attempt to chemically estimate cerebral energy metabolism, creatine and creatinine was measured in cerebrospinal fluid and plasma of up to 135 patients with RDC diagnoses of major depressive disorders. A strong positive age effect and a significant subdiagnostic difference were detected for both substances in CSF, but not in plasma. Primary unipolar patients had higher concentrations than either secondary unipolar or bipolar patients. Further, the two CSF measures correlated highly significantly and positively with the CSF monoamine metabolites HVA and 5-HIAA and the purine metabolites hypoxanthine and xanthine. Results indicate alterations in energy metabolism to be involved in affective disorders as well as in the regulation of monoamine and purine turnover.

Adolescent↗
PubMed1988

The prevalence of insomnia: the importance of operationally defined criteria.

Previous studies on the prevalence of sleep disturbances have shown that insomnia occurs in 3.2-42% of different populations. The wide reported variation in prevalence prompted a rigorous definition of insomnia to be introduced in this study. Randomly selected members of the population aged 30 to 65 years from two geographically different rural parts of central Sweden answered a sleep questionnaire. The response rates were 69.2% and 70.2%, respectively. Females significantly more often reported difficulty in falling asleep (7.1% of the women and 5.1% of the men). Among women 8.9 and among men 7.7% of individuals reported trouble with nocturnal awakenings. Using a stringently defined concept of insomnia as a disorder of initiating sleep (DIS), the prevalence rate of insomnia among women was 1.1% and among men 0.5%. Defining insomnia as a disorder of maintaining sleep (DMS), the prevalence among both women and men was 1.1%. Defining insomnia as a disorder of initiating and maintaining sleep (DIMS), the prevalence rate was 1.7% among women and 1.4% among men. This prevalence, which is lower than previously reported, demonstrate the importance of an operational definition of insomnia.

Adult↗
PubMed1987

Monoamine neurotransmitter interactions and the prediction of antidepressant response.

Clinical studies of monoamine neurotransmitter function in depression have concentrated on individual monoamines without focusing on interactions between monoamine systems. Virtually all modern studies have found significant correlations between monoamine metabolite concentrations in cerebrospinal fluid (CSF). These correlations should in part reflect interactions between central monoamine systems. In the present analysis, CSF had been obtained from depressed patients before (n = 40) and after (n = 36) antidepressant treatment. The patients were grouped based on their response to treatment. Absolute concentrations of CSF monoamine metabolites (homovanillic acid, 5-hydroxyindoleacetic acid, and 3-methoxy-4-hydroxyphenylethyleneglycol) did not differ between the two groups before or after treatment. However, when correlations between metabolites were compared, nonresponders to treatment differed considerably from responders. In responders, as in previously described normal populations, all three metabolites correlated with one another before and after treatment, and treatment-induced changes in metabolite concentrations also correlated with one another. In contrast, metabolites in nonresponders did not correlate with one another before treatment, nor did treatment-induced changes correlate with one another in this group. Furthermore, correlations between treatment-induced changes in metabolites differed significantly between responders and nonresponders, and there was a trend for pretreatment correlations to differ as well. The lack of correlation between monoamine metabolites in nonresponders suggests that interactions between monoamine systems may be disrupted in these individuals. Using CSF metabolite correlations to study neurotransmitter interactions may have clinical relevance and yields information not available from examining neurotransmitters in isolation.

Adult↗
PubMed1987

The effects of antidepressants on the cerebrospinal fluid homovanillic acid/5-hydroxyindoleacetic acid ratio.

Dopamine and serotonin systems are morphologically interconnected in the midbrain. Several studies have also demonstrated a functional relationship between these two monoamine systems. Concentrations of their metabolites, 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA), consistently correlate with one another in human cerebrospinal fluid. Previous studies of the effects of antidepressants on the dopamine and serotonin systems have focused on the two systems in isolation without considering the interactions between the two. One way of taking this interaction into account may be to form a ratio of dopamine and serotonin measures. The present study measured HVA and 5HIAA in cerebrospinal fluid of 31 patients with depression and 12 patients with Alzheimer's disease before and after treatment with a variety of antidepressant drugs. The ratio of HVA/5HIAA was able to discriminate much more powerfully between effects of different drugs than HVA or 5HIAA examined separately.

Alzheimer Disease↗
PubMed1986

Circadian covariation of norepinephrine and serotonin in the locus coeruleus and dorsal raphe nucleus in the rat.

We report robust correlations between concentrations of the neurotransmitters norepinephrine and serotonin in the locus coeruleus and the dorsal raphe nucleus of the brainstem in rats analyzed at 7 different time points over 24 h. We found similar circadian rhythmicities for both monoamines with acrophases just before the onset of the dark period. The monoamine concentrations diminished and the significant intercorrelation between norepinephrine and serotonin in the locus coeruleus disappeared during the night suggestive of a noradrenergic stimulation of dorsal raphe serotonin during the day. Timing of experiments is crucially important in studies on brain monoaminergic indices and their interrelationships.

Animals↗
PubMed1986

Serotonin turnover in discrete hypothalamic nuclei and mesencephalic raphe nuclei of young and adult spontaneously hypertensive rats.

Serotonin levels and turnover were analyzed in discrete forebrain and mesencephalic nuclei of young (4-week-old) and adult (14-week-old) spontaneously hypertensive rats and age-matched normotensive control Wistar Kyoto rats. Most changes observed were age-dependent, and occurred only in young, early hypertensive rats. Both serotonin levels and the accumulation rate of 5-hydroxy-tryptophan after L-amino acid decarboxylase inhibition were higher in the nuclei periventricularis and paraventricularis of the hypothalamus of young hypertensive rats than in controls. In addition, 4-week-old spontaneously hypertensive rats showed higher 5-hydroxytryptophan accumulation rates in the nuclei supraopticus and dorsomedialis of the hypothalamus than controls. The only difference in serotonin metabolism found in adult hypertensive rats was high serotonin concentration in the median eminence of the hypertensive animals. Our results suggest the presence of anatomically specific, age-dependent alterations in serotonin metabolism, localized to selected hypothalamic nuclei in young hypertensive rats. These data support a role for the hypothalamic serotonin in the development of the spontaneous (genetic) hypertension in the rat.

5-Hydroxytryptophan↗