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Biomedical subjects

A Lundberg

Publications and source records attributed to A Lundberg.

At least 19 recordsLinked to original sources
PubMed2000

Effects of foot orthoses on skeletal motion during running.

OBJECTIVE: To quantify the effects of medial foot orthoses on skeletal movements of the calcaneus and tibia during the stance phase in running. DESIGN: Kinematic effects of medial foot orthoses (anterior, posterior, no support) were tested using skeletal (and shoe) markers at the calcaneus and tibia. BACKGROUND: Previous studies using shoe and skin markers concluded that medially placed orthoses control/reduce foot eversion and tibial rotation. However, it is currently unknown if such orthoses also affect skeletal motion at the lower extremities. METHODS: Intracortical Hofman pins with reflective marker triads were inserted under standard local anesthetic into the calcaneus and tibia of five healthy male subjects. The three-dimensional tibiocalcaneal rotations were determined using a joint coordinate system approach. Eversion (skeletal and shoe) and tibial rotation were calculated to study the foot orthoses effects. RESULTS: Orthotic effects on eversion and tibial rotations were found to be small and unsystematic over all subjects. Differences between the subjects were significantly larger (p<0.01; up to 10 degrees ) than between the orthotic conditions (1-4 degrees ). Significant orthotic effects across subjects were found only for total internal tibial rotation; p<0.05). CONCLUSIONS: This in vivo study showed that medially placed foot orthoses did not change tibiocalcaneal movement patterns substantially during the stance phase of running. RELEVANCE: Orthoses may have only small kinematic effects on the calcaneus and tibia (measured with bone pins) as well as on the shoes (measured with shoe markers) during running of normal subjects. Present results showed that orthotic effects were subject specific and unsystematic across conditions. It is speculated that orthotic effects during the stance phase of running may be mechanical as well as proprioceptive.

Adult↗
PubMed2000

Movement coupling at the ankle during the stance phase of running.

The purpose of this study was to quantify movement coupling at the ankle during the stance phase of running using bone-mounted markers. Intracortical bone pins with reflective marker triads were inserted under standard local anaesthesia into the calcaneus and the tibia of five healthy male subjects. The three-dimensional rotations were determined using a joint coordinate system approach. Movement coupling was observed in all test subjects and occurred in phases with considerable individual differences. Between the shoe and the calcaneus coupling increased after midstance which suggested that the test shoes provided more coupling for inversion than for eversion. Movement coupling between calcaneus and tibia was higher in the first phase (from heel strike to midstance) compared with the second phase (from midstance to take-off). This finding is in contrast to previous in-vitro studies but may be explained by the higher vertical loads of the present in-vivo study. Thus, movement coupling measured at the bone level changed throughout the stance phase of running and was found to be far more complex than a simple mitered joint or universal joint model.

Adult↗
PubMed1999

A new method for estimating the axis of rotation and the center of rotation.

A new method is presented for estimating the parameters of two different models of a joint. The two models are: (1) A rotational joint with a fixed axis of rotation, also referred to as a hinge joint and (2) a ball and socket model, corresponding to a spherical joint. Given the motion of a set of markers, it is shown how the parameters can be estimated, utilizing the whole data set. The parameters are estimated from motion data by minimizing two objective functions. The method does not assume a rigid body motion, but only that each marker rotates around the same fixed axis of rotation or center of rotation. Simulation results indicate that in situations where the rigid body assumption is valid and when measurement noise is present, the proposed method is inferior to methods that utilize the rigid body assumption. However, when there are large skin movement artefacts, simulation results show the proposed method to be more robust.

Artifacts↗
PubMed1999

An in vitro comparison of bone deformation measured with surface and staple mounted strain gauges.

Chicken tibiae were chosen as a model for human second metatarsals. Local surface bone deformation in a 4-point bending configuration was measured in vitro by both strain gauge instrumented staples and strain gauges bonded to the bone's cortical surface. A series of staple bridge dimensions (0.5, 0.6, 0.8 and 1.0 mm) was compared to test for staple influence on bone characteristics and greatest measurement validity and reliability. Thicker staple inhibition of bone deformation was the greatest but differences to thinner staples were not statistically significant (p > 0.05). All staples except 0.5 mm had maximum deviations from linearity less than 1%. The 1.0 mm staple had an R2 value of 0.992 +/- 0.006 plotted against the 4-point bending input force and 0.994 +/- 0.002 plotted against the surface strain gauge signal. The mean intraclass correlation coefficients (ICC) calculated with four input forces (30, 60, 90 and 120 N) and for loading and unloading conditions for the 0.5, 0.6, 0.8 and 1.0 mm staples were 0.75, 0.83, 0.87 and 0.92, respectively. Finally, the differences in slope of the staple strain gauge signal plotted against surface strain gauge signal between input force loading and unloading conditions (0.32), and between input compression and tension conditions (0.79) was least for the 1.0 mm staple which also resulted in the lowest standard deviations. These results suggested the appropriateness of the 1.0 mm staple for in vivo application.

Animals↗
PubMed1998

Assortative mating and female clutch investment in black grouse.

Variation in female behaviour has only recently received attention in studies of sexual selection. It has been suggested that females may invest differentially in their offspring in relation to the quality of their mate. This may lead to females that mate with high-quality and/or attractive males laying larger clutches. Females may also differ in their ability to choose between males. For example, females in good physical condition may make better choices. If physical condition and clutch size are positively correlated, this hypothesis could also produce a relationship between male attractiveness and female clutch size. We found, in lekking black grouse, Tetrao tetrix, that females mated to the highest ranked males laid the largest clutches. Furthermore we found, regardless of female age, a positive relationship between a measure of female condition and male rank but not between female condition and her clutch size. In addition, females in good condition visited a larger number of different male territories, and old females produced the largest clutches. Our results suggest two mechanisms to explain our findings. First, females in good physical condition tend to mate with the top males, suggesting an assortative mating pattern. Second, females mating with the highest ranked males lay larger clutches as a consequence of their choice. In general, our result calls for caution in evaluating studies that look at the consequences of mate choice. It may be that differences in female quality produce effects that may be wrongly interpreted as male quality effects. (c) 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Control of claw movements in cats.

In cats with the distal paw shaved and the claws painted with nail varnish, claw movements were recorded during the approach to a morsel of food with a conventional video camera; supplementary results were obtained with a high frequency video system. The claws can be protruded in two directions, either ventrally or more dorsalwards. Measurements of the outer contour of the paw suggest that these two modes are not due to differences in angular movements in the proximal interphalangeal joints; it is suggested that they depend on some (so far unknown) function in the distal interphalangeal joints. Differential movements of the claws of the different digits suggest some degree of individual control of the digits.

Animals↗
PubMed1998

Role of claws and pads in taking and holding food in cats.

In order to investigate the role of claws and pads in taking food the planter surface of the distal forelimb paw was recorded with a conventional video camera. The claws were involved in the great majority of trials. The morsel of food may be taken by piercing with one claw (rarely two) either alone or by pressure against a digital pad; support by pressure from another claw was also common, while pressure between two claws was used more rarely. Another technique was pressure between claws (without piercing) and digital pads. The morsel was also taken without participation of claws by pressure between digital pads and the central pad and more rarely between two digital pads.

Animals↗
PubMed1998

Food-taking in the cat investigated with transection of the rubro- and corticospinal tracts.

In cats with the distal paw shaved food-taking from a horizontally or vertically placed tube was recorded with a video camera, supplementary results were obtained with a high frequency video system. Measurements were made of the dorsal contour of the digits to investigate angular movement in the proximal interphalangeal (PIP) joint and withdrawal of the paw before and after complete transection of the rubro- and corticospinal tracts just rostral to the forelimb segments. In the preoperative state PIP flexion occurs before withdrawal of the paw in the large majority of cats. Postsurgically the main part of PIP flexion is made during withdrawal of the paw. It is suggested that PIP flexion before withdrawal allows for accurate manipulative placement of the digits on the target which depends on the rubro- and corticospinal tracts, while PIP flexion during withdrawal, which may favour speed at the expense of accuracy, can be made without the rubro-and corticospinal tracts.

Animals↗
PubMed1998

Mechanical load and primary guinea pig osteoarthrosis.

Hartley guinea pigs spontaneously develop knee osteoarthrosis. The reproducible course, the changes first appearing at the central medial condyle and then progressing peripherally and laterally, makes this animal a suitable model for intervention studies. We studied the effect of load, and randomized 9-month-old male animals into 4 groups: immediate killing, mid-femoral 30 degrees-valgus osteotomy, sham operation or below-knee amputation. After 3 months, the proximal tibia was step-sectioned and examined stereologically by light microscopy. Local load-redistribution from the medial to the lateral condyle (osteotomy) reduced cartilage fibrillation by 22% medially and increased it 27% laterally. Subchondral bone thickness decreased by 36% in the medial condyle. In contrast, general load-redistribution (amputation) did not affect the progress of fibrillation, despite pronounced bone atrophy. Cartilage thickness, however, did not change; calcified cartilage thickness remained remarkably constant, and it was always higher on the lateral side. Therefore tide-mark advancement does not appear to be an important mechanism in early guinea pig osteoarthrosis. Thus, when the natural course of guinea pig osteoarthrosis is interfered with surgically, in the early phase, changes in bone are more conspicuous than those in cartilage, which further indicates that mechanical load and stiffness gradients are important pathogenetic mechanisms.

Amputation, Surgical↗
PubMed1997

Fluctuating asymmetry and copulation success in lekking black grouse

In lekking black grouse, Tetrao tetrixmales at the centre of the leks obtain more copulations than males at the edges. We found that males with territories at the edge of the lek obtained fewer matings and also have the most asymmetric tarsi. However, when considering the tail ornament (the lyre) no correlation between asymmetry and mating success was found. Although females are unlikely to select males on the basis of tarsus symmetry, asymmetry in this trait may reflect male condition. We suggest that males in poor condition, as reflected by higher levels of fluctuating asymmetry in the tarsi, do not achieve central positions on the lek arena. This would account for the lower success of males with higher levels of fluctuating tarsus asymmetry.

Journal Article↗
PubMed1997

Effect of skin movement on the analysis of skeletal knee joint motion during running.

It is not known how well skin markers represent the skeletal knee joint motion during running. Hence the purpose of this investigation was to compare the skin marker derived tibiofemoral motion with the skeletal tibiofemoral motion during running. In addition to skin markers attached to the shank and thigh, triads of reflective markers were attached to bone pins inserted into the tibia and femur. Three-dimensional kinematics of the stance phase of five running trials were recorded for three subjects using high-speed cine cameras (200 Hz). The knee motion was expressed in terms of Cardan angles calculated from both the external and skeletal markers. Good agreement was present between the skin and bone marker based knee flexion/extension. For abduction/adduction and internal/external knee rotation, the difference between skeletal and external motion was large compared to the amplitude of these motions. Average errors relative to the range of motion during running stance were 21% for flexion/extension, 63% for internal/external rotation, and 70% for abduction/adduction. The errors were highly subject dependent preventing the realization of a successful correction algorithm. It was concluded that knee rotations other than flexion/extension may be affected with substantial errors when using skin markers.

Adult↗
PubMed1997

Effect of spinal cord lesions on forelimb target-reaching and on visually guided switching of target-reaching in the cat.

Cats were trained to reach to an illuminated tube placed horizontally at shoulder level and retrieve food with the forepaw. The trajectory of an infrared light emitting diode, taped to the wrist dorsum, was recorded with a SELSPOT-like recording system. Movement paths and velocity profiles were compared before and after lesions: (1) in dorsal C5, transecting cortico- and rubrospinal pathways to the forelimb segments so that the cats could only use the C3-C4 propriospinal neurones (PNs) to command reaching, (2) in the ventral part of the lateral funicle in C5, transecting the axons of C3-C4 PNs so that the cats had to use circuitry in the forelimb segments to command reaching. Comparison of trajectories and velocity profiles before and after lesion 1 did not reveal any major qualitative change. After lesion 2, the last third of the movement was fragmented with separate lifting and protraction. Switching of target-reaching occurred when illumination was shifted to another tube during the ongoing movement. The switching latency measured from the time of illumination shift to the earliest change in movement trajectory had a minimal value of 50-60 ms. Short latencies were present after lesion 1 as well as lesion 2 which suggest that fast switching mediated by the C3-C4 PNs and the interneuronal system in the forelimb segments is controlled in parallel by the brain. In order to test a hypothesis that fast switching depends on the tectospinal and tecto-reticulospinal pathways (the tecto-reticulo-spinal system) a ventral lesion was made in C2 aiming at interrupting these pathways. Large ventral C2 lesions tended to block conduction in the more dorsally located rubrospinal (less in corticospinal) axons probably due to compression during surgery. When conduction in the rubrospinal tract was completely interrupted by a ventral C2 lesion which also completely transected the axons of the tecto-reticulo-spinal system, then there was a prolongation of the switching latency with 10-20 ms. After a similar large ventral lesion with remaining conduction in the rubrospinal tract the switching latencies were unchanged. It is postulated that fast visually governed switching does not depend on the tecto-reticulo-spinal system alone but on more dorsally located pathways, presumably the rubrospinal tract, either acting alone or together with the tecto-reticulo-spinal system. It is further postulated that the delayed switching after interruption of conduction both in the rubrospinal tract and the tecto-reticulo-spinal system depends on the corticospinal tract. Visual control of rubrospinal and of corticospinal neurones is considered. It is postulated that target-reaching normally depends on signals in the cortico- and rubrospinal tracts and mechanisms for co-ordination of activity in them as required during switching is discussed in view of the findings now reported.

Animals↗
PubMed1997

An experimental in vivo method for analysis of local deformation on tibia, with simultaneous measures of ground reaction forces, lower extremity muscle activity and joint motion.

This paper presents the pilot procedures of a new in vivo experimental method for measures of local bone deformation on tibia. The tibia transducer consists of a strain gauge mounted on a surgical staple, and was designed to measure local bone deformation. Pilot measurements were undertaken during two standardized conditions of forefoot and heel landing in seven healthy volunteers. Implantation of two tibia force transducers on tibia were performed under local anaesthesia. The local peak tibia deformation occurred at 20-42 ms (median) after ground contact, and was up to eight times higher during stance phase loading compared with standing still on one leg. Ground reaction forces, muscle activation patterns and kinematics were registered simultaneously, and were used to validate that the observed local deformation on tibia occurred under controlled and clinically relevant conditions. The new method may be used for investigating local deformation within various bone structures of the lower extremity. There are further methodological issues to address before major clinical interpretations may be concluded. In order to verify that the strain gauge transducer system was valid, a controlled displacement of the staple shanks was performed with a micrometer, and showed a linear relationship between applied deformation and strain gauge response (r = 0.97-0.99). In addition, a linear relationship was found between externally applied static forces and strain gauge response in a four-point bending cadaver system (r = 0.96-0.98).

Adult↗
PubMed1996

Early-onset myopathy with tubular aggregates.

We report a 14-year-old girl with early onset of slowly progressive muscular weakness and atrophy. There was no family history of neuromuscular disease. A persistent increase of serum creatine kinase was found. Muscle biopsy specimens showed type 1 fiber predominance and tubular aggregates in almost every fiber. The clinical findings and pathology suggest that the disease represents one variant in a group of rare myopathies with different patterns of inheritance, characterized by slowly progressive muscle weakness and tubular aggregates.

Adolescent↗
PubMed1996

Psychiatric aspects of air pollution.

Psychological and toxic effects of air pollution can lead to psychiatric symptoms, including anxiety and changes in mood, cognition, and behavior. Increased levels of some air pollutants are accompanied by an increase in psychiatric admissions and emergency calls and, in some studies, by changes in behavior and a reduction in psychological well-being. Numerous toxic pollutants interfere with the development and adult functioning of the nervous system. Manifestations are often insidious or delayed, but they can provide a more sensitive indicator of toxic effects than cancer rates or mortality data. Other medical effects of air pollution, such as asthma, can indirectly affect psychological health. The sick building syndrome and multiple chemical sensitivity are conditions with toxicologic and psychiatric aspects. Psychosocial stress can cause symptoms similar to those of organic mental disorders. Reactions to stress depend on cultural, individual, and situational variables. We must understand these factors to be able to alleviate and prevent the consequences of environmental trauma. Expanded research is recommended in three main areas: (1) how people perceive and cope with environmental health risks, (2) the effects of air pollution on behavior and neuropsychological functioning, and (3) neurotoxicologic evaluation of air pollutants with both behavioral and in vitro studies.

Adaptation, Psychological↗
PubMed1996

Three-dimensional tongue surface shapes of English consonants and vowels.

This paper presents three-dimensional tongue surfaces reconstructed from multiple coronal cross-sectional slices of the tongue. Surfaces were reconstructed for sustained vocalizations of the American English sounds [symbol: see text]. Electropalatography (EPG) data were also collected for the sounds to compare tongue surface shapes with tongue-palate contact patterns. The study was interested also in whether 3-D surface shapes of the tongue were different for consonants and vowels. Previous research and speculation had found that there were differences in production, acoustics, and linguistic usage between the two groups. The present study found that four classes of tongue shape were adequate to categorize all the sounds measured. These classes were front raising, complete groove, back raising, and two-point displacement. The first and third classes have been documented before in the midsagittal plane [cf. R. Harshman, P. Ladefoged, and L. Goldstein, J. Acoust. Soc. Am. 62, 693-707 (1976)]. The first three classes contained both vowels and consonants, the last only consonants. Electropalatographic patterns of the sounds indicated three categories of tongue-palate contact: bilateral, cross-sectional, and combination of the two. Vowels used only the first pattern, consonants used all three. The EPG data provided an observable distinction in contact pattern between consonants and vowels. The ultrasound tongue surface data did not. The conclusion was that the tongue actually has a limited repertoire of shapes and positions them against the palate in different ways for consonants versus vowels to create narrow channels, divert airflow, and produce sound.

Female↗
PubMed1995

Kinematics of the normal arch of the foot and ankle under physiologic loading.

We studied 15 cadaver feet to determine three-dimensional motion of selected tarsal bones under axial loading at three different loading levels. We determined the motion of individual joints and also the rotation of the tarsal bones in relation to the tibia. Joint rotations increased consistently with higher loads. The naviculartalar joint had the greatest total screw axis rotation, which averaged 9.4 degrees +/- 2.2 degrees at 667 N of load, followed by the first metatarsal-navicular (mean, 7.2 degrees +/- 1.5 degrees), talartibial (mean, 5.2 degrees +/- 1.6 degrees), and calcaneal-talar (mean, 4.4 degrees +/- 1.7 degrees) joints. The observed changes indicate the need for assessment of foot and ankle alignment clinically and radiologically while the patient is weightbearing.

Aged↗