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Biomedical subjects

P Ström

Publications and source records attributed to P Ström.

At least 19 recordsLinked to original sources
PubMed2006

High-level visual-spatial ability for novices correlates with performance in a visual-spatial complex surgical simulator task.

BACKGROUND: This study addresses how high-level visual-spatial ability of surgical novices is related to performance of two simulator tasks with (KSA) and without (MIST) anatomic graphics and haptic feedback, differing in visual-spatial complexity. METHODS: Visual-spatial test scores assessed by Mental Rotation Test (MRT) and BasIQ and performance scores for Instrument Navigation (IN) in Key Surgical Activities (Procedicus KSA) and Manipulate and Diathermy (MD) in Minimally Invasive Surgical Trainer (Procedicus MIST) were correlated for 54 Swedish surgical novices. RESULTS: Significant Pearson's r correlations were obtained between visual-spatial scores measured by MRT-C and total score from the last trial for IN (r = 0.278, p < 0.05). Visual-spatial scores (measured by BasIQ) also correlated with total score from the first trial (r = 0.443, p < 0.05) and from the last trial (r = 0.489, p < 0.05). CONCLUSION: High-level visual-spatial ability is important for surgical novices to possess in the early training phase of a visual-spatial complex task in KSA.

Adult↗
PubMed2006

Early exposure to haptic feedback enhances performance in surgical simulator training: a prospective randomized crossover study in surgical residents.

BACKGROUND: In the literature of skill acquisition and transfer of skills, it often is assumed that the rate of skill acquisition depends on what has been learned in a similar context (i.e., surgical simulators providing haptic feedback). This study aimed to analyze whether the addition of haptic feedback early in the training phase for image-guided surgical simulation improves performance. METHODS: A randomized crossover study design was used, in which 38 surgical residents were randomized to begin a 2-h simulator training session with either haptic or nonhaptic training followed by crossover after 1 h. The graphic context was a virtual upper abdomen. The residents performed two diathermy tasks. Two validated tests were used to control for differences in visual-spatial ability: the BasIQ general cognitive ability test and Mental Rotation Test A (MRT-A). RESULTS: After 2 h of training, the group that had started with haptic feedback performed the two diathermy tasks significantly better (p < 0.05, unpaired t-test). Only the group that had started with haptic training significantly improved during the last 1-h session (p < 0.01, paired t-test). CONCLUSION: The findings indicate that haptic feedback could be important in the early training phase of skill acquisition in image-guided surgical simulator training.

Abdomen↗
PubMed2003

Training in tasks with different visual-spatial components does not improve virtual arthroscopy performance.

BACKGROUND: We earlier showed that training in the Procedicus KSA Simulator improves the performance of tasks done later in the same simulator. However, it is still unclear how performance in a specific visual-spatial simulator context may change after training in other simulators with different visual-spatial components. In particular, the aim of this study was to test whether performance in the Procedicus Virtual Arthroscopy (VA) Knee Simulator would remain unchanged after a training session in three other simulators with different visual-spatial components. METHODS: Twenty-eight medical students participated in a quasi-transfer study. They were randomly allocated to an experimental group ( n = 14) and a control group ( n = 14). RESULTS: Performance in the Procedicus VA Knee Simulator did not improve after training in other simulators with different visual-spatial components ( t-test p = NS). No significant correlation was found between the Procedicus VA Knee and the Minimally Invasive Surgical Trainer (MIST) simulators. CONCLUSION: One hour of training in different visual-spatial contexts was not enough to improve the performance in virtual arthroscopy tasks. It cannot be excluded, however, that experienced trainees could improve their performance, because perceived similarity between different situations is influenced by many psychological factors, such as the knowledge or expertise of the person performing the transfer task.

Adult↗
PubMed2002

Validation and learning in the Procedicus KSA virtual reality surgical simulator.

BACKGROUND: Advanced simulator training within medicine is a rapidly growing field. Virtual reality simulators are being introduced as cost-saving educational tools, which also lead to increased patient safety. METHODS: Fifteen medical students were included in the study. For 10 medical students performance was monitored, before and after 1 h of training, in two endoscopic simulators (the Procedicus KSA with haptic feedback and anatomical graphics and the established MIST simulator without this haptic feedback and graphics). Five medical students performed 50 tests in the Procedicus KSA in order to analyze learning curves. One of these five medical students performed multiple training sessions during 2 weeks and performed more than 300 tests. RESULTS: There was a significant improvement after 1 h of training regarding time, movement economy, and total score. The results in the two simulators were highly correlated. CONCLUSION: Our results show that the use of surgical simulators as a pedagogical tool in medical student training is encouraging. It shows rapid learning curves and our suggestion is to introduce endoscopic simulator training in undergraduate medical education during the course in surgery when motivation is high and before the development of "negative stereotypes" and incorrect practices.

Computer Simulation↗
PubMed1996

Ten-year follow-up study of signs and symptoms of craniomandibular disorders in adults with intact and restored dentitions.

Signs and symptoms of craniomandibular dysfunction (CMD) and oral parafunctions were re-examined in subjects, 25-26 years of age, 10 years after the first examination. Forty subjects had restored dentitions at both examinations (group F), 18 subjects with previously intact dentitions had had fillings in their teeth during the follow-up period (group FI), and 11 subjects had intact dentitions at both examinations (group I). Signs and symptoms of CMD were more common among the subjects in group F than in the original group of subjects with intact teeth (group 10). In accordance with the first study most of the symptoms were mild and of low frequency. However, frequent symptoms were only found among the subjects in group FI and group F and more severe frequent symptoms only in group F. There was an increase of the symptoms in group FI and group F. Frequent tooth clenching and frequent tongue pressing were more common in group F and there was a statistically significant increase in group FI concerning tooth clenching and tooth grinding and in group F concerning tooth grinding, tooth clenching and tongue pressing. Together with the correlations found between tooth clenching and signs and symptoms of CMD, the findings in this study and the personality study indicate a possible causal relationship between oral parafunctions, signs and symptoms of CMD, personality and fillings. A hypothesis for the possible mechanisms is presented. However, the findings are not conclusive and more studies are necessary, and for further interpretation of the results, studies from other research centres would be of interest.

Adult↗
PubMed1994

Adult human osteoblast-like cells do not express insulin-like growth factor-I.

Previous studies using cultures of fetal rodents calvaria have indicated an important role for insulin-like growth factor-I (IGF-I) in the local control of bone formation. In this study, we have examined the expression of IGF-I in adult human osteoblast-like (hOB) cells. To detect very low levels and to distinguish between the two IGF-I mRNA transcripts Ea and Eb, which are formed by alternate splicing, we have used the reverse transcriptase-polymerase chain reaction (RT-PCR). Expression of both Ea and Eb IGF-I mRNA transcripts were found in human liver and in placenta. However, neither Ea nor Eb IGF-I mRNA could be detected under basal conditions or after stimulation with growth hormone in normal hOB cells and two human osteosarcoma cell lines with osteoblastic properties, SaOS-2 and MG-63. We conclude that adult hOB cells do not synthesize IGF-I. Thus, in contrast to its crucial role as a local regulator of skeletal remodeling in fetal rodent bone, IGF-I does not appear to have this autocrine function in adult human bone.

Base Sequence↗
PubMed1991

NCQ 298, a new selective iodinated salicylamide ligand for the labelling of dopamine D2 receptors.

NCQ 298 ((S)-3-iodo-N-[(l-ethyl-2-pyrrolidinyl)methyl]-5,6- dimethoxysalicylamide) has an iodine substituent. We have labelled NCQ 298 with 123I and 125I, and used the radioligands as tracers in receptor studies in vitro, in vivo in autoradiography and in SPECT studies on Cynomolgus monkeys. [125I]NCQ 298 bound in vitro to a single binding site with a KD = 19 pM. NCQ 298 has thus a 10-fold higher affinity for the dopamine D2 receptors than the corresponding des-5-methoxy compound FLA 961 (IBZM), previously used in SPECT studies. The binding of [125I]NCQ 298 was entirely reversible (T1/2 = 17.5 min at 37 degrees C). Autoradiographical studies in vitro on rat and monkey brain tissue sections showed a distinct binding in caudate-putamen, nucleus accumbens, substantia nigra, and in layer 5 of the cerebral cortex. In vivo binding studies in mice showed a ratio of 10 between [125I]NCQ 298 binding in striatum and cerebellum. Binding was displaced by the selective dopamine D2 receptor antagonist raclopride. In SPECT studies with [123I]NCQ 298 in two Cynomolgus monkeys, radioactivity accumulated in the basal ganglia. The measured striatum to cerebellum ratio was about 15 after 3 h. A monkey brain phantom was constructed for the determination of conversion factors from pixel events to actual radioactivity. The resulting, corrected striatum to cerebellum ratio obtained was 30. After administration of 12 mg raclo-pride to one of the monkeys there was a substantial decrease in striatal radioactivity. [125I]NCQ 298 is a suitable ligand for the labelling of dopamine D2 receptors in vitro and in vivo. The specific properties of [123I]NCQ 298 suggest that this compound is a useful ligand for quantitative SPECT studies of dopamine D2 receptors in man.

Animals↗
PubMed1991

A comparative PET-study of five carbon-11 or fluorine-18 labelled salicylamides. Preparation and in vitro dopamine D-2 receptor binding.

Five 11C- or 18F-labelled salicylamides ([11C]raclopride (I), [11C]eticlopride (II), [18F]NCQ 258 (III), [18F]NCQ 134 (IV) and [18F]NCQ 135 (V] were prepared. The total radiochemical yields of I-V from EOB were 3-30% (decay-corrected) with an overall synthesis time of 40-110 min. All compounds were isolated by semi-preparative HPLC and the radiochemical purity was greater than 99%. I-V were in separate experiments injected into Cynomolgus monkeys for PET-examination of ligand distribution in brain in vivo. I-V passed rapidly across the blood-brain barrier. With both analogs I and II there was a high uptake in the striatum, a region with a high density of dopamine D-2 receptors. With the 18F-labelled analogs III and IV, the uptake in the striatum was almost identical to that in the dopamine receptor poor cerebellum whereas the striatal uptake of V was clearly higher than in the cerebellum. Unlabelled I-V (raclopride, eticlopride, NCQ 258 (VII), NCQ 134 (VIII) and NCQ 135 (IX)) were also prepared and examined in vitro using [3H]raclopride and [3H]spiperone binding to rat striatal dopamine D-2 receptors. A significantly lower affinity was shown for NCQ 258 and NCQ 134 (5 times) compared to that of raclopride and eticlopride, respectively, whereas the affinity of NCQ 135 was similar to that of eticlopride.

Animals↗
PubMed1991

Potential antipsychotic agents. 9. Synthesis and stereoselective dopamine D-2 receptor blockade of a potent class of substituted (R)-N-[(1-benzyl-2-pyrrolidinyl)methyl]benzamides. Relations to other side chain congeners.

A number of substituted N-[(1-benzyl-2-pyrrolidinyl)methyl]benzamides and -salicylamides have been prepared and investigated as dopamine D-2 receptor antagonists in vitro and in vivo. The affinity was found to be confined to the R enantiomer, in contrast to the corresponding N-ethyl or N-allyl derivatives. The X-ray structure of one of the compounds (15) confirmed the R stereochemistry. This compound (15) was found to adopt a solid-state conformation in which the 4-fluorobenzyl group is folded over the salicylamide moiety. Benzamides having a 2,3-dimethoxy substitution pattern (24 and 26) or salicylamides with a 5,6-dimethoxy grouping (21 and 22) were especially potent, in that they inhibited [3H]spiperone binding to rat striatal dopamine D-2 receptors in vitro with IC50 values of about 1 nM. The new compounds' ability to block apomorphine-induced stereotypies correlated with the affinity for the [3H]spiperone binding site. Higher dose levels were necessary to induce catalepsy than to block the apomorphine-induced responses. The influence of the aromatic substituents on the potency of substituted benzamides with three types of side chains, i.e. (R)-(1-benzyl-2-pyrrolidinyl)methyl, (S)-(1-ethyl-2-pyrrolidinyl)methyl and 1-benzyl-4-piperidinyl, was compared. The 3-bromo-5,6-dimethoxysalicylamide substitution pattern was found to be the most general since it gave very potent compounds in all series. The substituted (R)-N-[(1-(4-fluoro-benzyl)-2-pyrrolidinyl)methyl]benzamides (26) and -salicylamides (22) are suitable for development into 18F radioligands without altering the parent structure.

Animals↗
PubMed1991

Five-year longitudinal recordings of functional variables of the masticatory system in adolescents with intact and restored dentitions. A comparative anamnestic and clinical study.

Recordings of functional variables of the masticatory system were made in 184 subjects, 18-20 years old, 5 years after the first examination. One hundred and six subjects had restored dentitions at both examinations (group F), 35 subjects with previously intact dentitions had received fillings during the follow-up period (group FI), and 43 subjects had intact dentitions at both examinations (group I). In conformity with the first examination 5 years earlier, the subjects in group F had higher scores for dentin facets on the first lower molar. Together with the finding of more frequent attrition on the distal part of the occlusal surface of the second lower molar, this finding indicates more functional or parafunctional activity in restored dentitions. Unilateral contacts in the retruded contact position (RCP) were equally common in all three groups, but the contacts in RCP were more often located in the molar region in group F. The finding at the first examination that interference causing a lateral slide of the mandible between RCP and the intercuspal position (ICP) was commoner in restored dentitions was not confirmed in the present study. Nor did the correlation analysis show any relationship between occlusal factors and signs and symptoms of mandibular dysfunction. However, the differences found between subjects with intact and restored dentitions indicate that the iatrogenic effect of dental filling therapy merits more consideration and more extensive research.

Adolescent↗
PubMed1991

Five-year follow-up of mandibular dysfunction in adolescents with intact and restored dentitions: a comparative anamnestic and clinical study.

Signs and symptoms of mandibular dysfunction were re-examined in 189 subjects, aged 18 to 20 years, 5 years after the first examination. One hundred nine subjects had restored dentitions at both examinations (group F), 36 subjects with previously intact dentitions had had fillings in their teeth during the follow-up period (group FI), and 44 subjects had intact dentitions at both examinations (group I). The subjects with restored dentitions had a higher degree and frequency of mandibular dysfunction than the subjects with intact teeth. The subjects who had had fillings during the follow-up period (group FI) constituted a group between groups F and I with respect to signs and symptoms of mandibular dysfunction. This strengthens the authors' earlier suspicions that dental filling therapy is of greater etiologic importance in mandibular dysfunction than had been thought previously. However, more studies are necessary to find the exact mechanisms involved.

Adolescent↗
PubMed1990

Potential antipsychotic agents 5. Synthesis and antidopaminergic properties of substituted 5,6-dimethoxysalicylamides and related compounds.

A series of 3-substituted 5,6-dimethoxysalicylamides III (9-13 and 15) has been synthesized from the corresponding 2,5,6-trimethoxybenzoic acids. Relaxation times T1 and carbon chemical shifts of the methoxy groups in III showed that the 6-methoxy group adopts a nearly perpendicular orientation and the 5-methoxy group takes on a more coplanar orientation with respect to the ring plane in solution. The salicylamides III display a very high and stereoselective affinity for the [3H]spiperone and [3H]raclopride binding sites in vitro. Regioisomeric salicylamides IV also exhibit pronounced, but lower than III, affinity for the [3H]spiperone binding site. The structural requirements were further assessed by studies of the related amino analogues 23 and 24 and hydroxy analogue 27. The 3-bromo compound 11 (FLB 463) was studied in various in vivo models and compared with the dopamine-D2 antagonists sulpiride, raclopride, eticlopride, and haloperidol. The high potency of 11 to selectively block dopamine-D2 receptors in vitro and in vivo combined with indications on a low potential for motor side effects makes it a very interesting new member of the class of substituted salicylamides.

Animals↗
PubMed1990

Syntheses of [123I]-, [125I]- and unlabelled (S)-3-iodo-5,6-dimethoxy-N-[(1-ethyl-2-pyrrolidinyl)methyl]salicylamide (NCQ 298), selective ligands for the study of dopamine D-2 receptors.

The salicylamide NCQ 298, (S)-3-iodo-N-[(1-ethyl-2-pyrrolidinyl)methyl]-5,6-dimethoxysalicylami de (4), binds with a high affinity and selectivity to central dopamine D-2 receptors. In the present paper the synthesis of NCQ 298 and the efficient labelling both with 123I and 125I are described. The unlabelled NCQ 298 was synthesized by iodination of (S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-2,5,6-trimethoxybenzamide followed by demethylation with boron tribromide, which produced 4 and the regioisomer 5 in a ratio of 82:18. The two isomeric salicylamides were separated by radial chromatography and tested for their abilities to inhibit the binding of [3H]raclopride to rat striatal membranes in vitro in relation to some representative salicylamides. The 5,6-dimethoxysalicylamide 4 (NCQ 298) was found to be considerably more active than the corresponding 6-methoxysalicylamide 10 (FLA 961 or IBZM). The radioligands [123I]NCQ 298 and [125I]NCQ 298 were prepared in a carrier-free form from the corresponding desiodo compound by the chloramine-T protocol and isolated by semipreparative HPLC. The total radiochemical yields of [123I]NCQ 298 and [125I]NCQ 298 (based on [123I]- and [125I]iodide and decay-corrected) were 88% and 93%, respectively, with a radiochemical purity of greater than 99%. [125I]NCQ 298 will be studied to evaluate its potential as a radioligand in studies requiring a high specific activity, selectivity and high potency to label dopamine D-2 receptors. [123I]NCQ 298 has potential as a radioligand for the in vivo examination of central dopamine D-2 receptors in human brain by Single Photon Emission Computed Tomography (SPECT).

Animals↗
PubMed1988

Homoallylic amines related to zimeldine. A comparative study on neuronal serotonin and norepinephrine reuptake based on conformational analysis.

A number of tertiary and secondary homoallylic amines, i.e. (Z)- and (E)-4-(4-bromophenyl)-4-(3-pyridyl)-3-buten-1-ylamines, were synthesized in diastereomerically pure forms. The compounds were evaluated as neuronal norepinephrine (NE) and serotonin (5-HT) uptake inhibitors under in vitro and ex vivo conditions and compared with the tricyclics amitriptyline and nortriptyline having homoallylic side chains and with the corresponding diastereomers in the zimeldine series having allylic side chains. The Z isomers of the new homoallylic derivatives (3Z, 4Z) were specific 5-HT uptake inhibitors in analogy with the corresponding allylic derivatives zimeldine (1Z) and norzimeldine (2Z). Likewise, the selectivity profile of the homoallylic (3E, 4E) and the allylic (1E, 2E) derivatives was comparable. In general, the homoallylic compounds were less potent inhibitors than their allylic counterparts. The similarities and discrepancies were evaluated in terms of conformational preferences determined by CAMSEQ molecular mechanics calculations. Homonorzimeldine (4Z) can accommodate energetically favored, but less populated, conformations having amino nitrogen atom to aromatic ring center distances comparable to those in norzimeldine. These facts correlate to retained 5-HT selectivity but diminished potency of 4Z compared to 2Z.

Animals↗
PubMed1986

Mandibular dysfunction related to dental filling therapy. A comparative anamnestic and clinical study.

A group of 96 individuals, 13 to 15 years of age, with intact teeth was compared with a control group of 129 individuals with dental restorations, with regard to occurrence of mandibular dysfunction. Statistically significant differences between the groups were established at both the anamnestic and the clinical examination, with a lower frequency and degree of dysfunction among those with intact teeth. Conforming with the findings of a previous study on 17- to 23-year-olds, these findings indicate that filling therapy may be associated with mandibular dysfunction.

Adolescent↗
PubMed1984

Facet pattern in intact and restored dentitions of young adults. A comparative study.

The attritional dental pattern was studied clinically and on plaster casts in a group of individuals, 17-22 years old, with intact teeth and in a control group with a 'normal' distribution of dental restorations. The following observations were made: 1) all contact areas between occluding teeth exhibited facets; 2) most facets were located on inclines; 3) facets in the fossa bottom occurred oftenest in the control group and often involved fillings; 4) attritional facets on the distal marginal crest of the lower second molars were oftenest found in the control group; 5) denuded dentin in facets occurred oftenest in the control group; and 6) the number of facets and the worn areas were on an average largest in the control group. The findings in this study indicate a difference in the functional activity between the groups and support the hypothesis that dental fillings can induce changes in the neuromuscular pattern of the masticatory system.

Adolescent↗
PubMed1983

Dental filling therapy as a possible etiological factor regarding mandibular dysfunction. A comparative anamnestic and clinical study.

A group of 29 individuals, 17-23 years old, with intact teeth, has been compared with a control group with respect to occurrence of mandibular dysfunction. A statistically significant difference between the groups, with a lower frequency and degree of dysfunction among the intact individuals was established. The results suggest that filling therapy per se may be a possible etiological factor in the mandibular dysfunction. Disorders in the masticatory neuromuscular system may arise from an abnormal tactile response to contacts on fillings, including an abnormal pattern of mandibular movement, possibly exceeding the tolerance level of the system.

Adolescent↗