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Biomedical subjects

B Mårtensson

Publications and source records attributed to B Mårtensson.

At least 19 recordsLinked to original sources
PubMed1996

Accuracy of orthodontic force and tooth movement measurements.

This study was designed to test the accuracy of measurement methods for assessment of force and tooth movement in orthodontic procedures. Daily in vivo measurements of the force produced by activated archwires showed that the initial force declined substantially (by 20 per cent of mean value) within 3 days. Both the 'trueness' (validity) and precision of the force measurements, obtained with a strain gauge, were found to be high (SD values were 1.0 cN and 0.4 cN, respectively). Horizontal tooth movements were measured with three different instruments: a slide calliper, a co-ordinate measuring machine, and laser measuring equipment based on holograms. There was a good level of agreement between these methods. This was also confirmed by calibration data. The precision of the methods was (SD values) 0.06, 0.07, and 0.13 mm, respectively. The benefits of the use of the co-ordinate measuring machine are obvious, since it can measure tooth movements in relation to reference planes in all directions.

Adolescent↗
PubMed1994

A comparison of propofol and methohexital as anesthetic agents for ECT: effects on seizure duration, therapeutic outcome, and memory.

The effects of the anesthetic agents propofol and methohexital on seizure duration, clinical outcome, recovery, and memory in electroconvulsive therapy (ECT) were studied in a double-blind trial. The study comprised 53 patients, 47 patients with major depression and six patients with other diagnoses according to DSM-III. Several recent clinical studies with a crossover design have shown a reduced seizure duration for anesthesia with propofol in comparison with both methohexital and thiopental. Propofol significantly reduced the seizure duration in this study without reducing the therapeutic outcome as measured by the Montgomery-Asberg Depression Rating Scale. Propofol did not significantly alter the length of the course of ECT; however, a slightly prolonged course for women cannot be completely ruled out. There were no significant differences between the two agents in effects on recovery times after anesthesia and on anterograde memory. In general, it seems that propofol is as effective as methohexital as an induction agent for ECT.

Adult↗
PubMed1993

Serotonin selective antidepressant drugs: past, present, future.

Classic antidepressant drugs, amine uptake inhibitors of the imipramine type and the monoamine oxidase inhibitors, alter the functioning of serotonin (5-hydroxytryptamine, 5-HT) neurons in the brain. This discovery, made more than two decades ago, has had a profound impact on the study of depressive illness as well as on the development of new models of antidepressant treatment. Apart from their obvious clinical value, antidepressant drugs have come to be used as research tools to study the pathophysiology of depressive illness. A main goal in the development of antidepressant drugs has been to design drugs with more selective effects on the nerve cells that are thought to be important in depressive illness, thereby avoiding unnecessary side effects and possibly enhancing therapeutic effects. Drugs that selectively affect 5-HT neurons have proved to be uptake inhibitors--including fluoxetine, fluvoxamine, paroxetine, sertraline, and citalopram--and are now available. All of them appear to have an antidepressant effect equivalent to standard reference compounds, with a different spectrum of side effects. One of the most interesting aspects of the serotonergic drugs is their broad spectrum of action, in particular, their effects in patients with obsessive-compulsive disorder, panic disorder, and possibly some disorders of impulse control. There is still relatively little knowledge of which aspects of 5-HT function are important for the antidepressant, antiobsessive, and antipanic effects. The availability of drugs that selectively affect the different 5-HT receptors, such as the partial 5-HT1A agonist gepirone, will presumably be helpful for modern studies of the "anatomy of melancholy."

Antidepressive Agents↗
PubMed1992

The holodent system, a new technique for measurement and storage of dental casts.

A system for producing holograms and for three-dimensional measuring on holograms is described. The precision of the system was evaluated when three-dimensional measurements were made on (1) a holographic image superimposed on the corresponding object and (2) two superimposed holographic images of the same object. When a metal test object with sharp well-defined contours, easy to reorientate was used, the precision was 0.02 to 0.11 mm for x, y, and z coordinates (transverse, longitudinal, and vertical planes). When dental casts that have less distinct contours were used, precision was reduced to 0.03 to 0.43 mm. Precision was high for the x and y coordinates and satisfactory for the z coordinate. The system has a precision that is equal to that of previously reported methods and may be well-suited for studies of dental positional changes in longitudinal materials of study models. Holograms of dental casts may solve storage problems by replacing space consuming plaster models.

Dental Records↗
PubMed1991

Memory effects of clomipramine treatment: relationship to CSF monoamine metabolites and drug concentrations in plasma.

Performance on tasks tapping automatic and voluntary aspects of memory, attention, and motor speed was examined in 14 patients with major depressive disorder, before and after 3 weeks of treatment with clomipramine (150 mg/day), a potent serotonin and noradrenaline uptake blocker with anticholinergic side effects. Performance on tasks requiring frontal functions improved or did not change, whereas verbal learning and retention, where hippocampal functioning is critical, were impaired. The latter tasks were negatively related to cerebrospinal fluid (CSF) 5-HIAA levels and plasma concentration of clomipramine. The results provide further support for the regulatory role of monoaminergic systems in cognition. Furthermore, we found the automatic-voluntary capacity distinction less heuristically useful. Physiological mechanisms regulating different aspects of cognition and memory appeared to be more closely related to the type of task used than to its capacity-demanding properties.

Adult↗
PubMed1991

Effects of clomipramine treatment on cerebrospinal fluid monoamine metabolites and platelet 3H-imipramine binding and serotonin uptake and concentration in major depressive disorder.

In an open study of 12 inpatients who met the DSM-III criteria for a major depressive episode, the effects of clomipramine (CI) on the monoamine metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), 4-hydroxy-3-methoxyphenyl glycol (HMPG) in cerebrospinal fluid (CSF) were measured simultaneously with the effects on 3H-imipramine binding, serotonin (5-HT) uptake and 5-HT concentration in platelets after 3 and 6 weeks of treatment. Drug (CI and desmethylclomipramine) plasma concentrations were determined. The concentrations of 5-HIAA and HMPG decreased substantially, and the concentration of HVA remained unchanged. There was also a large and significant reduction of the number of imipramine binding sites (Bmax) and of the platelet 5-HT concentration. The 5-HT uptake was not measurable after 3 weeks of treatment. None of the parameters changed significantly between weeks 3 and 6. There were no significant correlations between antidepressant effect (measured by the Montgomery-Asberg Depression Rating Scale) and plasma drug concentrations, although a tendency to a significant correlation between antidepressant effect and CI was observed at 3 weeks. There were no significant intercorrelations between the different 5-HT parameters and no other significant correlations between the biochemical measures and clinical outcome.

Adult↗
PubMed1991

Chromatography of selenoproteins in human serum using matrix-bound heparin.

Since previous experiments indicated that a major selenoprotein in human serum interacts with heparin, chromatography of serum on matrix-bound heparin was studied. When human serum was applied to heparin-agarose columns, approximately half of the applied selenium was not retained on the columns. Approx. 40% of the selenium could then be eluted either with increasing concentrations of heparin or ammonium acetate. Using a scaled-down version of this procedure, selenoproteins from 0.5 ml serum were separated into the heparin-binding and non-heparin-binding fractions. In an experiment where healthy subjects were given supplements of yeast selenium (200 micrograms/d) for eight weeks, the concentration of selenium in serum was almost doubled and then approached the original concentration 16 weeks after the end of the supplementation. During supplementation, no change in the concentration of heparin-binding selenoproteins was observed, and instead the increase in serum selenium occurred in non-heparin-binding proteins. This suggests that the need for selenium by the heparin-binding proteins was saturated already at the starting serum selenium level (1.0 mumol/l). Since interaction with heparin has been observed also for selenoprotein P isolated from rat plasma, the protein in the heparin-binding fraction, demonstrated in this paper, may be a human analogue to selenoprotein P.

Adult↗
PubMed1990

Effects of fluoxetine treatment of platelet 3H-imipramine binding, 5-HT uptake and 5-HT content in major depressive disorder.

Platelet 3H-imipramine binding, serotonin (5-HT) uptake and 5-HT concentrations were studied in 14 hospitalized patients with depressive disorder following 6 weeks of treatment with a selective 5-HT uptake blocker, fluoxetine. After 3 weeks of treatment there was a significant decrease in Bmax of 3H-imipramine binding and a significant increase in Kd. A highly significant decrease in Vmax of 5-HT uptake was seen after 3 weeks of treatment which was accompanied by a slight increase in Km. At the same time the platelet 5-HT content was significantly reduced by about 90% of its original level. The platelet 5-HT content continued to decrease with further treatment while there was a tendency for Vmax to return to pretreatment levels. The affinity of the 5-HT uptake carrier continued to decrease significantly. There was no further significant change in Bmax of 3H-imipramine binding during further treatment, although there was an increase in Bmax in the majority of patients. The changes in Bmax and Vmax were closely associated throughout the treatment. In some cases the changes in different platelet parameters correlated with the changes in depression rating scores during treatment, but this correlation did not reach statistical significance.

Adult↗
PubMed1989

Aberrant seasonal variations of platelet serotonin uptake in endogenous depression.

The serotonin uptake in platelets of 120 healthy volunteers and 64 endogenously depressed patients was investigated over a 2-year period. In healthy individuals, Km exhibited a significant seasonal rhythm during the bright half of the year. The seasonal rhythm of Vmax assumes the form of a sine curve, with nadir values at the vernal and autumn equinoxes and peak values at the winter and summer solstices. Km in patients was higher than in controls in February and October, and the seasonal variation of Km differed between patients and controls. The monthly mean values of Vmax in patients were, as a rule, lower than corresponding values in controls, but significantly so only in December. Patients had higher Vmax than controls in October and November, and the seasonal variation of Vmax in patients differed from that of controls. The results suggest that Km, a measure of the affinity of the serotonin uptake site, may be subject to photoperiodic regulation in healthy individuals. The annual variation in uptake site densities, as judged by the changes in Vmax, are probably generated by an endogenous superior oscillator. The aberrant uptake kinetics found in the endogenously depressed patients may reflect seasonal susceptibility to the disorder and/or altered serotonergic rhythmicity.

Adolescent↗
PubMed1989

Fluoxetine treatment of depression. Clinical effects, drug concentrations and monoamine metabolites and N-terminally extended substance P in cerebrospinal fluid.

In an open study of depressed inpatients, the effects of the selective serotonin uptake blocker fluoxetine on 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), 4-hydroxy-3-methoxyphenyl glycol (HMPG) and N-terminally extended substance P (SP) in cerebrospinal fluid (CSF) were measured. Thirteen unmedicated patients who met the DSM-III criteria for major depressive episode were included, and 9 completed the study. During treatment the 5-HIAA concentration decreased by 46%. The HVA and HMPG concentrations also decreased significantly, but to a lesser degree. The mean level of N-terminally extended SP was unaffected by fluoxetine treatment, but the pretreatment level correlated significantly with the pretreatment level of HMPG. The pretreatment level of HVA was the only biochemically variable that appeared to predict therapeutic outcome. The plasma concentrations of both fluoxetine and its metabolite norfluoxetine increased significantly between 3 and 6 weeks. Plasma and CSF levels of both the parent drug and its active metabolite were correlated.

Adult↗
PubMed1988

Heparin interacts with a selenoprotein in human plasma.

The major selenium-containing peak at gel filtration of human serum on Sephadex G-150 had a Kav of 0.19, but at chromatography of heparinized plasma this peak had a Kav of 0.01, indicating an interaction between heparin and a major selenium-containing protein. The addition of protamine abolished the effect of heparin. The heparin-interacting protein was not identical to glutathione peroxidase. The data explain some previous discrepancies on selenium distribution in plasma due to the use of different anticoagulants.

Blood Proteins↗
PubMed1987

Effects of antidepressant treatments on platelet tritiated imipramine binding in major depressive disorder.

The effects of four antidepressant treatments on platelet tritiated imipramine binding have been studied in 51 hospitalized patients with severe major depressive disorder. There was an increase in maximum binding (Bmax) during the first week of treatment with antidepressants and electroconvulsive therapy, which was further magnified after three weeks' treatment with the serotonin uptake blockers alaproclate and zimeldine hydrochloride, but the Bmax values returned to baseline levels with nortriptyline hydrochloride and electroconvulsive therapy. The equilibrium dissociation affinity constant (Kd) did not change with any of the treatments. On reexamination one or two years after admission to the study, Bmax had not reached control values in clinically recovered, drug-free patients. Low pretreatment Bmax was associated with delusions during illness and with a poor long-term clinical outcome. There was no correlation between binding parameters and monoamine metabolite concentrations in the cerebrospinal fluid, either before or during treatment.

Adult↗
PubMed1986

Therapeutic effects of serotonin uptake inhibitors in depression.

Depression has been associated with a disturbance in serotonin function as reflected in platelet uptake of the transmitter as well as in CSF levels of its major metabolite, 5-hydroxyindoleacetic acid (5-HIAA). CSF 5-HIAA levels are subnormal in approximately 30% of melancholia patients. Early studies suggested that patients with a disturbed serotonin metabolism were less responsive to treatment with uptake inhibitors with a preferential action on noradrenaline neurons. Such findings encouraged the search for compounds with a selective effect on serotonin neurons. Although some classical antidepressants are potent inhibitors of serotonin uptake, they are not selective, since their metabolites, which appear to have antidepressant effects, inhibit noradrenaline uptake. The consistent findings of an increased risk for suicide in patients with low CSF 5-HIAA underlines the importance of exploring drugs that act on serotonin transmission. The biochemical effects of some serotonin uptake inhibitors and their clinical and research potential in depression are reviewed.

5-Hydroxytryptophan↗
PubMed1985

Lower 3H-imipramine binding in platelets from untreated depressed patients compared to healthy controls.

3H-Imipramine binding in platelets was measured in 63 severely depressed hospitalized patients, who had been drug free (with the exception of moderate doses of benzodiazepines) for at least 1 month, and in 53 healthy control subjects of comparable age and sex distribution. Bmax of 3H-imipramine binding was significantly lower in the depressed subjects (1012 +/- SD 295 vs. 1123 +/- SD 178 fmole/mg protein). Depressed patients who had attempted suicide by violent means tended to have higher Bmax than nonviolent attempters.

Adult↗
PubMed1984

CSF monoamine metabolites in melancholia.

The neurotransmitter metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA) and 4-hydroxy-3-methoxyphenyl glycol (HMPG) in cerebrospinal fluid (CSF) were measured by mass fragmentography in 83 patients with melancholia (diagnosed by the Newcastle Inventory and the Research Diagnostic Criteria), and 66 healthy volunteer controls. After adjustment by analysis of covariance for differences between the subject groups in body height, age and sex distribution, significantly (P less than 0.001) lower concentrations of 5-HIAA and HVA were found in the melancholia patients than in the controls. HMPG did not differ between the groups. The differences could not be accounted for by differences in timing or examination techniques, and not by previously administered drugs (all patients were drug-free at the examination, but a minority had taken small amounts of psychotropic drugs prior to the wash-out period). The differences persisted after excluding the suicidal patients. There were no clear-cut differences between unipolar and bipolar patients. It is suggested that the reduced concentrations of 5-HIAA and HVA in the melancholic patients may be due to altered serotonin and/or dopamine functions in the central nervous system, which may be connected with an increased vulnerability to certain types of affective illness.

Adult↗