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Biomedical subjects

A Björk

Publications and source records attributed to A Björk.

At least 19 recordsLinked to original sources
PubMed1995

Intramatrix rotation--the frontal bone.

Intramatrix rotation during growth and development was studied by 2-D cephalometric technique with the use of metallic implants in the frontal bone in five patients at the Centre for Craniofacial Anomalies, Malmö General Hospital. The analysis of the frontal bone in the five patients showed rotations of the corpus inside the periosteal matrix from 1 to 9.5 degrees in the mid-sagittal plane. The essential conclusion of these observations is that an intramatrix rotation takes place during the development of the frontal bone. This observation will stimulate further studies of its nature, amount, and direction.

Adolescent↗
PubMed1994

Preclinical pharmacology of FG5893: a potential anxiolytic drug with high affinity for both 5-HT1A and 5-HT2A receptors.

The effects of FG5893 were evaluated by several different methods; rats were used as experimental animals. Receptor binding studies revealed that FG5893 (2-(4-(4,4-bis(4-fluorophenyl)butyl)-1-piperazinyl)-3-pyridinecarboxy lic acid methyl ester) binds with high affinity to both 5-HT1A (Ki = 0.7 nM) and 5-HT2A receptors (Ki = 4.0 nM) but has only low affinity for the 5-HT2C receptor (Ki = 170 nM). FG5893 dose dependently reduced body temperature, and this effect was inhibited by pretreatment with (+/-)-pindolol. FG5893 (0.1 mg/kg) significantly inhibited head twitch behaviour induced by DOI (1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane) and FG5893 was also a potent inhibitor of ultrasound vocalization in rat pups (0.3 mg/kg) and of a passive avoidance response (0.1 mg/kg) in mature animals. FG5893 inhibited the cage-leaving response and induced part of the 5-HT behavioural syndrome, but only at very high doses (5 and 10 mg/kg, respectively). At increased doses (1 mg/kg), FG5893 also elicited corticosterone release and reduced the immobility time in the forced-swim test (1 mg/kg). Together, these data indicate that the mixed 5-HT1A receptor agonist/5-HT2A receptor antagonist FG5983 is a potent stimulator of presynaptic 5-HT1A receptors but is less active at the postsynaptic site. FG5893 had potent anxiolytic-like effects both on separation-induced ultrasound vocalization in rat pups and on a passive avoidance response. At increased doses, FG5893 possessed an antidepressant-like property.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1994

Endovascular treatment of a spinal arteriovenous malformation in a 21-month-old boy.

Reports of spinal arteriovenous malformations in children are rare. This case report describes a 21-month-old boy whose first symptom was attacks of abdominal pain, followed gradually by neurological symptoms. The diagnosis was made using magnetic resonance imaging and spinal angiography, and the patient was successfully treated with embolization.

Aortography↗
PubMed1994

In the search for a novel class of antipsychotic drugs: preclinical pharmacology of FG5803, a 1-piperazinecarboxamide derivative.

Comparative studies of the 1-piperazinecarboxamide derivative 4-[3-(4-fluorobenzoyl)propyl]-N-cyclohexyl-1-piperazinecarboxamide hydrochloride (FG5803) were made with clozapine and haloperidol. Receptor studies revealed that FG5803 potently and selectively bound to the serotonin type 2A receptors (Ki = 13 nM). FG5803 inhibited 5-hydroxytrophan- and 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane-induced head twitches, which indicated potent in vivo serotonin type 2A receptor antagonism. FG5803 caused an acute activation of the tuberoinfundibular dopamine neurons and produced only a transient rise in plasma prolactin. In behavioral studies in rats, FG5803 showed strong antagonistic action on presynaptic dopaminergic autoreceptors but only weak postsynaptic dopamine D2 blockade. FG5803 was not cataleptogenic and did not antagonize amphetamine-induced stereotypies. FG5803 was active in the reduction of aggressive behavior and spontaneous exploratory behavior in mice and rats. Therefore, FG5803 is expected to constitute a promising approach in the search for a novel class of antipsychotic drugs that have a broader spectrum of activity and fewer adverse effects than the conventional, antidopaminergic antipsychotics.

Animals↗
PubMed1993

Amperozide, a 5-HT2 antagonist, attenuates craving for cocaine by rats.

Amperozide, a novel 5-HT2 receptor antagonist with little affinity for the dopamine receptor, suppresses the intake of alcohol in rats without affecting food intake or inducing other side effects. Because of these actions, amperozide was examined for its efficacy on the oral preference by the rat for a solution of cocaine. In this study, rats were selected for their voluntary consumption of at least 10 mg/kg of cocaine per day in a two-choice paradigm. A solution of 0.02% to 0.06% cocaine plus 0.03% saccharin in water was offered to each animal simultaneously with a solution of only 0.03% saccharin in water. The consumption of food and both fluids, as well as body weight, was recorded daily for three successive periods: 4 days of pretreatment baseline; 3 days during injections of either amperozide or the saline vehicle solution; and 4 days postinjections. Amperozide was administered SC twice daily in a dose of 0.5, 1.0, or 2.5 mg/kg. The volitional intake of cocaine was significantly reduced not only during the 3-day period of injections of amperozide but also during the 4-day posttreatment period. Amperozide exerted little or no effect on the intake of food or on body weight. Radioligand binding experiments confirmed that amperozide has at least a twentyfold greater affinity for 5-HT2 receptors in the frontal cortex of the rat, as compared to striatal DA1 and DA2 receptors, with the proportion value similar to that of the 5-HT2 receptor antagonist, ritanserin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

5-HT2 receptor blockade by amperozide suppresses ethanol drinking in genetically preferring rats.

Previously, it was shown that the unique diphenylbutylpiperazinecarboxamide derivative, amperozide (FG 5606), inhibits the volitional drinking of ethanol induced in the rat by the inhibitor of aldehyde dehydrogenase, cyanamide. In this study, the efficacy of this long-acting psychotropic agent and potent 5-hydroxytryptamine2 (5-HT2) receptor antagonist was examined in the genetic line of ethanol-preferring (P) and -nonpreferring (NP) rats. In both lines, the pattern of drinking of ethyl alcohol was determined by a standard preference test for 3-30% ethanol vs. water. Then, the maximally preferred concentration of ethanol was determined for each individual, which ranged from 9-15% for P rats and 9-13% for NP animals. After a 4-day predrug test, either the saline control vehicle or amperozide was administered SC b.i.d. at 1600 and 2200 h. The drug was given over a 3-day period in one of three doses: 0.5, 1.0, or 2.5 mg/kg. The intake of ethanol of P rats was reduced significantly in a dose-dependent manner in terms of both absolute g/kg and proportion of ethanol to water during injections of amperozide. The same doses of amperozide had no effect on the low intake of ethanol in NP rats. The saline control vehicle also did not alter the consumption of ethanol of P or NP rats. Further, neither the consumption of food nor level of body weight was affected by amperozide either during or after its administration. These results demonstrate that in the individual predisposed genetically to drink ethanol amperozide exerts a palliative effect on the aberrant preference for ethanol consumed in a pharmacologically significant amount. Presently, dopaminergic and serotonergic synapses in the brain are implicated in the genetic differences in the patterns of ethanol consumption that distinguish the P from the NP line of rats. Because amperozide influences the functional activity of both dopaminergic and serotonergic neurons in the mesolimbic system, it is envisaged that the drug attenuates ethanol drinking by way of its direct action on these neurons.

Alcohol Drinking↗
PubMed1992

Selective reduction by the 5-HT antagonist amperozide of alcohol preference induced in rats by systemic cyanamide.

This investigation was undertaken to determine the effect of a unique psychotropic agent on the volitional drinking of alcohol induced pharmacologically in the rat by an inhibitor of aldehyde dehydrogenase. Following administration of cyanamide in a dose of 10 mg/kg twice daily for 3 days, the pattern of drinking of ethyl alcohol was determined in each of 12 Sprague-Dawley rats by means of a standard preference test for 3-30% alcohol vs. water. Then, each rat was offered water and its maximally preferred concentration of alcohol, which ranged from 7-15%. After a 4-day predrug test, either the saline control vehicle or the diphenylbutylpiperazinecarboxamide derivative, amperozide, was administered subcutaneously. The injections of amperozide were given b.i.d. at 1600 and 2200 h over 3 days in a dose of 0.5, 1.0, or 2.5 mg/kg. The intake of alcohol during the sequence of amperozide injections was significantly reduced in a dose-dependent manner in terms of both absolute g/kg and proportion of alcohol to water intake, whereas the saline control vehicle was without any effect on alcohol consumption. Although the highest dose of amperozide reduced the total intake of fluid due to the sharp decline in alcohol drinking, neither the consumption of food nor level of body weight was affected by any dose of the drug either during or after its administration. Because amperozide acts centrally on the synaptic activity of dopaminergic and serotonergic neurons in limbic system structures, it is envisaged that the drug ameliorates the aberrant drinking of alcohol by virtue of a direct effect on either one or both of these classes of neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMed1992

Long-term effect of rapid maxillary expansion studied in one patient with the aid of metallic implants and roentgen stereometry.

The articulatory displacement of maxillary bones during and after rapid maxillary expansion (RME) was studied with metallic implants and roentgen stereometry (RSA) for 3653 days in a girl aged 12 at start of treatment. She had a narrow upper dental arch with anterior crowding and a normal incisor relationship, and a normal sagittal molar relationship with bilateral cross-bite. Three implants were inserted in each maxillary bone and they remained stable in the bones during the 10-year observation period. In the 3-D analysis of the articulatory displacement, the left maxillary bone was studied in relation to the right bone in three periods: RME (23 days), retention (108 days) and follow-up (3522 days). Extensive relapse of rotations as well as translations was found and the long-term effect of RME was limited. In our opinion the relapse was caused mainly by the resistance to deformation from circum-maxillary sutures and surrounding soft tissue matrix, and inadequate bone formation in the involved sutures. As is generally known in clinical oral orthopaedics, changes obtained by short-term simple mechanical interference with a complex biological system tend to reverse spontaneously. Thus, the rationale for RME treatment may be seriously questioned.

Biomechanical Phenomena↗
PubMed1991

Effects of amperozide in schizophrenia. An open study of a potent 5-HT2 receptor antagonist.

Ten male inpatients (aged 29 +/- 6 years) with a DSM-III diagnosis of schizophrenia participated in a 4-week open dose escalation study of amperozide, a novel 5-HT2 receptor antagonist. The maximum daily dose of amperozide was 20 mg. A close dose-plasma concentration relationship showed considerable interindividual variation in the steady-state plasma levels at a given dose. Approximately equal concentrations of amperozide and its metabolite, N-deethylated amperozide, were seen in plasma. The prolactin levels were not increased during amperozide treatment. No changes occurred in hematological or other laboratory parameters. ECG showed changes in T-wave morphology and a prolongation of the QTc time. One patient was withdrawn from the trial due to aggravation of psychotic symptoms, and two patients had a brief, temporary discontinuation of the drug due to somatic illness. Six patients were improved during amperozide treatment, as assessed by the Clinical Global Improvement Scale. Among the responders the total CPRS was reduced by a mean of 64% and total BPRS score by a mean of 46%. Mild tremor was a frequent side effect, but other extrapyramidal symptoms were rare. Nausea was seen in six patients and of a more pronounced character in one patient. In general, the severity of the side effects increased with increasing doses of amperozide.

Adult↗
PubMed1991

[Achondroplasia: craniofacial growth in a boy followed for a 10-year period analyzed by an implant method].

The present report deals with the description of craniofacial morphology and growth in an achondroplastic boy followed for a 10-year period. The methods included roentgencephalometry, and metallic implants were inserted in both jaws. Thereby it became possible to differentiate between displacement of the jaws and their bone remodelling. The study showed that in the patient analyzed the primary cause of the worsening of the sagittal jaw relationship was to be found in the growth disturbances of the cranial base rather than in the growth of the jaws per se.

Achondroplasia↗
PubMed1991

Facial growth rotation--reflections on definition and cause.

The phenomenon of growth rotation of the jaws during facial development is examined by means of profile roentgencephalometric analysis of a male subject followed from age 4 years to adulthood, with reference to metallic implants and stable natural bony structures. The rotation of the corpora of the jaws, termed total rotation, and its components, matrix and intramatrix rotation, are defined. A description is given of the compensatory remodelling process. The concept of facial growth rotation as essentially a primary phenomenon is supported by a report of an identical facial rotation pattern in growing Macaca mulatta, suggesting that facial growth rotation is common in primates.

Adolescent↗
PubMed1990

A comparative study of two different methods of measuring stature and the velocity of growth in children and adults.

The stretched technique of measuring the stature described by Tanner (1962) is claimed to minimize the variation which occurs during the course of the day. This study examines differences in the calculated growth rate for the stretched and the conventional methods. The data for the analysis was drawn from a larger longitudinal growth study (Björk, 1968), where the stature of the individuals was measured both by the conventional unstretched technique according to Hrdlicka (1939) and by the stretched method described by Tanner (1962). A total of 84 individuals (48 boys and 36 girls) representing a total of 805 measurements of stature for each of the methods were included in the study. The individuals were measured annually until adult age, after which the measurements were made at intervals of 2-5 years. This represents a total range of 6-32 years of age, with individual series of observation varying over a period of 4-16 years. In accordance with the definition the stature measured by the stretched technique was significantly higher than measured by the unstretched method. The growth rate, however, at any age level did not differ significantly for the two methods and the variability in growth rate was the same. It was concluded that the unstretched technique gives similar values for estimating growth-velocity curves as does the stretched technique.

Adolescent↗
PubMed1988

Effects of amperozide on biting behavior and performance in restricted-fed pigs following regrouping.

Eight experiments were conducted to determine the effect of a single administration of amperozide on agonistic behavior and growth performance in newly mixed, restricted-fed pigs. Two hundred 12-wk-old pigs were used in a 4-wk trial (Exp. 1) to investigate the effect of amperozide on agonistic behavior and performance. The pigs were assigned to each pen on the basis of body weight and sex, ensuring that pigs in each pen were unacquainted. Each pig was weighed individually on d 3, 7 and 28. Agonistic behavior was quantified by counting bite and slash marks on each pig at 8, 26 and 48 h after penning. An i.m. injection of amperozide immediately before mixing the pigs reduced the physical damage (P less than .001) at each time point. There was no evidence of amperozide causing either sedation or motor disturbances. On the average, amperozide treatment improved (P less than .001) daily gain in the 4-wk study period by 70 g (17%). In Exp. 2 to 8, 1,648 pigs growing from approximately 20 to 100 kg body weight were used to determine the effect of amperozide on weight gain. Pigs were penned in groups of 9 to 11, randomly assigned to each pen on the basis of sex. Each pig was weighed individually after penning, on d 35 and at slaughter. Untreated control pigs had a poorer growth performance than did amperozide-treated pigs. During the first 5 wk postpenning average daily gain was improved (P less than .001) by 90 g (26%) in pigs receiving a single oral administration of amperozide at penning.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗
PubMed1986

Low-luminance myopia and dark vergence.

In normal binocular vision, under photopic conditions, accommodation and convergence act in synergy. We examined the relationship between these two functions in darkness, in the absence of all accommodative and fusional stimuli. Accommodation was measured as it is expressed in low-luminance myopia. There was no strong positive correlation between accommodation and vergence in darkness. Rather, the two systems were dissociated, and appeared to assume independent resting states with accommodation generally exceeding convergence.

Accommodation, Ocular↗
PubMed1985

Contrasting mandibular growth and facial development in long face syndrome, juvenile rheumatoid polyarthritis, and mandibulofacial dysostosis.

The complex rotation process of the mandible during growth is elucidated by longitudinal roentgencephalometric analyses, using metallic implants as fixed references. Contrasting development of face and mandibular shape is described in three subjects. In the so-called long face syndrome, development is characterized by increasing inclination of the mandible during growth with only moderate remodeling. In the subjects with juvenile rheumatoid polyarthritis and mandibulofacial dysostosis, the increase in mandibular inclination is moderate. However, the mandibular corpus rotates backward to an extreme extent within the more stable soft tissue matrix, giving rise to the characteristic development of angular notching with an extended angular process at the lower border.

Arthritis, Juvenile↗