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Biomedical subjects

M Magnusson

Publications and source records attributed to M Magnusson.

At least 55 records · Page 3Linked to original sources
PubMed2000

Asymmetric vestibular function in the elderly might be a significant contributor to hip fractures.

The aim of this study was to assess postural control, vestibular symmetry and health status in otherwise healthy hip fracture subjects and compare these factors with controls. The fracture subjects were recruited from 113 consecutive patients operated 12-33 months earlier. Nineteen of those were otherwise healthy and fulfilled the inclusion criteria. They were assessed and compared with 28 age- and sex-matched controls. Nystagmus after head shake was checked for by video-nystagmoscopy (charged couple device cameras). Vibration sensation was tested with a tuning fork, medical history and posturography of vibration-induced sway were studied. The subjects had a significantly higher frequency of head shake nystagmus (p = 0.03), indicating a vestibular asymmetry and a history of previous fractures (p = 0.002). Nine out of 12 subjects had fallen and sustained the hip fracture towards the slow phase of the nystagmus, which is expected in a vestibular related fall. Losing balance during testing was more frequent among the subjects than among the controls (p = 0.002). The subjects with head shake nystagmus swayed more than those without, especially in the sagittal plane during neck vibration with eyes closed (p < 0.001). Vibration perception was significantly poorer in the operated legs than in the healthy legs (p = 0.021) and in the legs of the controls (p = 0.001). The findings suggest that vestibular asymmetries may contribute to falls and fractures in elderly people. As such asymmetries can be compensated to a certain degree by specific training programs, these might be advisable for elderly people, especially those with a history of falls or fractures or where a vestibular asymmetry is suspected.

Aged↗
PubMed2000

Impact of child health centre organization on parental satisfaction.

The aim of this study is to describe differences in parental satisfaction with child health services under different organizational arrangements. The study had a cross-sectional design and was based on 3 largely identical surveys, involving 60 questions, performed in 1970, 1988 and 1993. The original questionnaire was developed by one of the authors in 1970. The present study analyses responses to 5 demographic questions and 12 questions regarding the content of child health services, evaluating parental satisfaction with these services. The study population in 1970 consisted of 443 parents (93% of those invited to participate) with children 6-18 months old, 1008 (82%) in 1988 and 1071 (80%) in 1993. Parents expressed more satisfaction with child health services in 1970 and 1993 compared to 1988. This pattern is not attributable to macro-level societal changes, but corresponds to changes in the organization of child health care services over the study period. The results highlight the vital question of how child health care should be organized in order to satisfy parents. The quality of child health care and parental satisfaction depend in part on the style of organization, including how much nurses with 'first-line' contacts focus on paediatric services.

Adult↗
PubMed1999

Carrier-mediated transport of monocarboxylic acids in BeWo cell monolayers as a model of the human trophoblast.

The monolayer-forming, human choriocarcinoma cell line, BeWo, was used to study the mechanisms of monocarboxylic acid transport across the human trophoblast. Benzoic acid, acetic acid, and lactic acid were used as markers for monocarboxylic acid carrier-mediated transport. The uptake of benzoic acid by BeWo cells was saturable (K(t) = 0.6 +/- 0.3 mM) at higher concentrations and significantly inhibited by typical metabolic inhibitors, sodium azide and 2, 4-dinitrophenol. A selection of different monocarboxylic acids, including a natural substrate lactic acid, also substantially inhibited the uptake of benzoic acid and acetic acid by BeWo cells, whereas dicarboxylic acids did not affect the uptake of either marker. Monocarboxylic acid uptake was pH-dependent and inhibited by carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), a protonophore. Kinetic analysis using Lineweaver-Burk plots revealed that monocarboxylic acids competitively inhibited the uptake of benzoic, lactic, and acetic acid by BeWo cells. In transport experiments, the permeation of benzoic acid from apical-to-basolateral side was greater than the permeation from the basolateral-to-apical side, and the transport of benzoic acid from apical-to-basolateral side was inhibited by monocarboxylic acids. The findings obtained in the present study confirm the existence of an asymmetric, carrier-mediated transport system for monocarboxylic acids across the BeWo cell, a representative of the human trophoblast.

Antimetabolites↗
PubMed1999

Reduction of visuo-spatial neglect with vestibular galvanic stimulation.

The purpose of the present investigation was to determine the effect of galvanic vestibular stimulation on visuo-spatial neglect without inducing nystagmus and associated discomfort. Fourteen patients with right-hemisphere stroke with neglect were assessed with two visuo-motor tasks ("Line crossing" and "Star cancellation") on three occasions. Seven of the subjects received galvanic vestibular stimulation during the second condition (Experiment 1), whereas the other seven received stimulation during the third assessment (Experiment 2). Between-group comparisons of stimulation effects were performed by analyzing change on visuo-spatial neglect from the first to the second condition in the two experimental groups. A significantly larger effect was demonstrated on the "Line crossing" task in Experiment 1. This finding suggests a stimulation effect beyond practice/spontaneous recovery, and may provide new possibilities in rehabilitation research because the stimulation can be given without discomfort.

Aged↗
PubMed1999

Child health service's response to early feeding and behaviour problems: changes in parental perceptions 1970-93.

OBJECTIVE: This health systems study was done to measure changes over time concerning parents' perceptions of feeding and behavioural problems in children 6-18 mo of age, parents' willingness to use child health services and their evaluation of the advice received. METHOD: The study had a repetitive cross-sectional design. Three largely identical surveys were performed in 1970, 1988 and 1993. Questionnaires were sent to a random sample of all parents of children 6-18 mo living in Uppsala, Sweden. RESULTS AND CONCLUSIONS: The frequency of different perceived feeding and/or behavioural problems was stable or declined between 1970 and 1988, but increased in 1993. For most problems, inclination to seek help and perceived benefit of advice decreased between 1970 and 1988, but increased again in 1993. The parents sought more help and perceived the advice they received as more beneficial when the service was in the hands of paediatric nurses (1970) or of district nurses focusing on the care of infants and preschool children (1993) than when the district nurses also had responsibilities for adults and the elderly (1988). No correlation was seen with societal and sociodemographic trends. Although the cross-sectional (hence non-experimental) design of the study makes it impossible to prove causality, the findings suggest that parents' willingness to use the child health service and their evaluation of that service may depend in part on organization, including the degree to which nurses with "first-line" contacts are focused on paediatric services.

Adult↗
PubMed1999

Isoforms of bone alkaline phosphatase: characterization and origin in human trabecular and cortical bone.

Alkaline phosphatase (ALP) is a glycoprotein and functions as an ectoenzyme attached to the cell membrane by a hydrophobic glycosyl-phosphatidylinositol (GPI) anchor. Three bone ALP (BALP) isoforms in human serum were separated and quantitated by high-performance liquid chromatography. B/I, a minor fraction, is composed on average of bone (70%) and intestinal (30%) ALP, and two major isoforms, B1 and B2. Treatment with GPI-specific phospholipase C (GPI-PLC) did not influence the activities or retention times for B1 and B2, indicating that the biochemical differences between B1 and B2 are likely to be due to different glycosylation patterns. The B/I fraction in serum, on average 4% of total ALP, was found to be composed of B1 and B2 isoforms, each with an intact hydrophobic GPI cell membrane anchor. We investigated the origin of these three BALP isoforms and osteocalcin in human femora from five healthy individuals (four males), mean age 51 years, obtained from a tissue bank. Bone was sampled from three sites: cortical bone, trabecular bone from the diaphysis, and trabecular bone from the greater trochanter. Trabecular bone, from both sites, had higher BALP activities compared with cortical bone. Conversely, the osteocalcin content of cortical bone was more than 3-fold greater than that of trabecular bone. Cortical bone had approximately 2-fold higher activity of B1 compared with B2, whereas trabecular bone had approximately 2-fold higher activity of B2 compared with B1. We observed a previously undescribed BALP isoform (B1x) in all bone samples. B1x was also observed in sera from some patients (60%) with severe renal insufficiency and on chronic dialysis therapy (n = 20). The isoforms of BALP may provide information relating to bone metabolism within specific bone compartments.

Adult↗
PubMed1998

[Perform vestibular test among all small deaf children! Early detection of Usher syndrome improves the possibilities of communication in the event of later deaf-blindness].

Although deaf children depend upon sight for communication, retinitis pigmentosa is present in 6 per cent of those with a profound hearing deficit. Usher syndrome type 1 (USH-1) is an autosomal recessive disease characterised by profound hearing impairment, absent vestibular function, and progressive loss of vision due to retinitis pigmentosa. Owing to the severe handicap of the combined disorders, early diagnosis of USH-1 is of crucial importance. The profound hearing deficit is often detected at hearing tests in infancy, but as the sight problems do not develop until later diagnosis is often delayed. The diagnosis of Usher's syndrome is established by electroretinography (ERG), as confirmation of the retinitis pigmentosa is a prerequisite. As the progressive deterioration of sight hinders the use of sign language, a cochlear implant constitutes an invaluable aid at an early age. Early diagnosis is thus of both medical and educative importance. To avoid delay in diagnosis past the age when optimal results may be expected from a cochlear implant, a screening test was sought for infants with profound hearing loss to identify those at increased risk of USH-1, for whom ERG is a priority. Although conventional vestibular testing methods are not well tolerated by infants, with recently developed equipment for video or CCI) (charge-coupled device) camera inspection of eye movements, vestibular screening can now be performed in the office. In our experience it is possible to screen most infants, given a careful approach by the investigator. Children with clinically diagnosed USH-1, without any vestibulo-ocular reflex, manifested no vestibular responses during 'video-nystagmoscopy' when rotated on the parent's lap, preliminary findings strongly suggest that vestibular function should be tested in all children with a profound congenital hearing deficit, as it is important for children with USH-1 to be provided with a cochlear implant permitting aural reception of communication from the environment at an early age, because of the progressive deterioration of vision and the ultimate double handicap.

Blindness↗
PubMed1998

Analysis of adaptation in anteroposterior dynamics of human postural control.

To quantify the postural adjustments over time, twelve normal subjects were investigated with posturography during vibration either toward the calf or the paraspinal neck muscles; with eyes open vs. eyes closed. The stimulus response adjustments over time were found to be almost identical for all test conditions, though the responses were smaller during eyes open conditions. To determine the response adjustments and thus the dynamics of postural control, a system identification methodology incorporating both step response and dynamic feedback components was developed. This methodology can be used to quantify both short-term stimulus response and postural adaptive adjustments when evaluating postural control performance. Copyright 1998 Elsevier Science B.V.

Journal Article↗
PubMed1998

Extrahepatic cytochrome P450: role in in situ toxicity and cell-specific hormone sensitivity.

It is clear that members of the Cytochrome P450 supergene family are responsible for the majority of activations of procarcinogens to ultimate carcinogens in the body. These procarcinogens include the food mutagens (heterocyclic amines), pesticides, polycyclic aromatic hydrocarbons and nitrosamines. The Cyp P450 profile in a cell can indicate the capacity of that cell to form reactive metabolites. Furthermore, environmental factors, through their action on P450s, influence the fate of procarcinogens in a cell. This is because different isoforms of P450 are regulated differently by ethanol, diet and environmental inducers, have different substrate specificities and different propensity to be inhibited or activated by dietary components. Cyp P450 (through steroid inactivation), can also influence sensitivity of cells to hormones. Age and hormone related regulation of P450 isoforms such as 1A1, 2B1 and 2A3 in the breast suggest that in situ activation of carcinogens and hormone inactivation can occur in the breast. In the brain and endometrium most of the #P450 isoforms remain to be identified.

Age Factors↗
PubMed1998

Head movement restriction and postural stability in patients with compensated unilateral vestibular loss.

OBJECTIVE: To study whether restriction of head-neck movements improves postural performance in patients with compensated unilateral total vestibular loss. DESIGN: Randomized controlled experimental study. SETTING: Laboratory for clinical and experimental vestibular testing at a tertiary referral center. PATIENTS: Fifteen consecutive patients (seven men, eight women, mean age 53 years) at routine follow-up, 6 months after translabyrinthine extirpation of acoustic neurinomas (mean tumor size 13.5mm, range 5 to 25mm). None of the patients had signs or symptoms of central nervous system dysfunction. INTERVENTION: Posturographic tests comparing patients with and without a semirigid neck collar. Test order was randomized between patients to reduce training effects. MAIN OUTCOME MEASURE: Posturography measuring velocity and variance of quiet stance and measuring body sway induced by vibration at 60, 80, and 100Hz to the calf muscles. Tests were conducted with eyes open and closed. RESULTS: In tests with vibration at 100Hz to the calf muscles and with eyes open, body sway velocity was significantly higher when patients were wearing a neck collar. No significant difference was found in any other test. CONCLUSION: Restricting head-neck movements with a neck collar does not improve postural stability in patients with compensated unilateral total vestibular loss. A tendency toward impaired postural performance leads to the conclusion that it is not appropriate to treat such patients with neck collars to improve their balance.

Adolescent↗
PubMed1998

Passive sustained turning of the head induces asymmetric gain of the vestibulo-ocular reflex in healthy subjects.

In order to test the hypothesis of an interaction between neck proprioception and the vestibulo-ocular reflex (VOR), we rotated 16 healthy subjects both facing forward and with their heads passively turned 70 degrees to either side. We found that gain tended to be lower when the subjects were rotated with their heads turned opposite to the direction of rotation compared to when they were rotated in the same direction, but facing forward. Although our findings were not statistically significant, they suggest that there is a measurable interaction between neck proprioception and the VOR in subjects with normal vestibular function. Asymmetric neck muscle proprioceptive signals seem to give rise to asymmetric functioning of the VOR, which, at least in part, could be the pathogenesis of cervical dizziness. If so, this could lead to misinterpretation of vestibular assessments in patients with neck pain who also complain of dizziness.

Adult↗
PubMed1998

Dual skin testing with Mycobacterium avium sensitin and purified protein derivative to discriminate pulmonary disease due to M. avium complex from pulmonary disease due to Mycobacterium tuberculosis.

Skin testing with Mycobacterium avium sensitin (MAS) RS 10/2 and purified protein derivative (PPD) was conducted on patients with pulmonary disease due to M. avium complex (MAC) or Mycobacterium tuberculosis (MTB) and no known immunodeficiency. Reactions > or = 5 mm to either MAS or PPD were present in 37 (84%) of 44 MAC patients and 28 (97%) of 29 MTB patients. MAC patients had a mean MAS reaction of 13.8 (+/-8.3) mm and a mean PPD reaction of 3.5 (+/-8.6) mm (P < .001). MTB patients had a mean MAS reaction of 17.9 (+/-9.4) mm and a mean PPD reaction of 22.9 (+/-11.4) mm (P < .001). MAS-dominant skin tests (MAS reaction > or = 5 mm larger than PPD reaction) were present in 32 (73%) of 44 MAC patients and 1 (3%) of 29 MTB patients. MAS-dominant skin tests had a specificity of 97% for discriminating MAC disease from MTB disease.

Adult↗
PubMed1998

Kappa Delta Award. Low back pain and whole body vibration.

The investigators describe their multifaceted approach to the study of the relationship between whole body vibration and low back pain. The epidemiologic study was a two center study of drivers and sedentary workers in the United States and Sweden. The vibration exposure was measured in the vehicles. It was found that the career vibration exposure was related to low back, neck, and shoulder pain. However, disability was related to job satisfaction. In vivo experiments, using percutaneous pin mounted accelerometers have shown that the natural frequency is at 4.5 Hz. The frequency response is affected by posture, seating, and seat back inclination. The response appears to be determined largely by the rocking of the pelvis. Electromyographic studies have shown that muscle fatigue occurs under whole body vibration. After whole body vibration exposure the muscle response to a sudden load has greater latency. Vehicle driving may be a reason for low back pain or herniated nucleus pulposus. Prolonged seating exposure, coupled with the whole body vibration, should be reduced for those recovering from these problems. Vibration attenuating seats and correct ergonomic layout of the cabs may reduce the risks of recurrence.

Acceleration↗
PubMed1998

Identification of CYP2A3 as a major cytochrome P450 enzyme in the female peripubertal rat breast.

On isolation of rat breast cytochrome P450, one of the proteins whose amino terminus was sequenced was CYP2A3. CYP2A3 was detected by Western blotting in cytochrome P450 fractions isolated from breast of 3-, 6-, and 9-week-old rats but was low during pregnancy and lactation. Reverse transcription-polymerase chain reaction analysis and sequencing of the PCR product confirmed the presence and identity of CYP2A3 in the rat breast. Breast microsomal coumarin-7-hydroxylase activity paralleled the developmental pattern observed for CYP2A3 on Western blots. In the lung, coumarin-7-hydroxylase activity was 10-fold higher than that in the breast, but the developmental pattern was similar to that in the breast. Lung microsomes from 9-week-old rats activated the heterocyclic amine 2-amino-3-methylimidazo[4,5-f]quinoline to mutagenic metabolites which could be detected with the Ames test. This activation could be inhibited by the CYP2A3 antiserum. With breast microsomes, which contain approximately 10% of the cytochrome P450 in the lung, activation of 2-amino-3-methylimidazo[4, 5-f]quinoline could not be reliably measured. Immunohistochemical localization revealed that CYP2A3 was expressed in a limited number of epithelial cells in the ducts of 6-week-old rat breast. Double staining with smooth muscle actin, a marker for myoepithelial cells, showed no staining of CYP2A3 immunoreactive cells, indicating that these cells were not myoepithelial. The data clearly show that a cytochrome P450 that can activate environmental procarcinogens is developmentally regulated and concentrated in specific cells in the breast. The peripubertal period seems to be a window in time when the breast may be more sensitive to procarcinogens that are substrates for CYP2A3.

Amino Acid Sequence↗
PubMed1998

Characterization of cytochrome P450 enzymes in human breast tissue from reduction mammaplasties.

Cytochrome P450 (CYP) enzymes in the breast may have an important role in regulating the capacity of individual cells to metabolize hormones and environmental carcinogens. Very little is known about the P450 expression pattern in human breast because of the limited amount of accessible tissue and the difficulties associated with detection of low P450 levels. Breast tissue from reduction mammaplasties is the only tissue available in relative abundance. The correlation between the P450 content in this material and P450 in breast epithelium remains to be resolved. Also questionable is the value of RT-PCR detection of P450 forms in the breast without parallel detection of the protein. In this study, we have tried to determine whether the P450 profiles in reduction mammaplasty samples reflect those in the breast epithelium and whether P450 profiles on Western blots parallel RT-PCR detection. A comparison on the level of RT-PCR was made between P450 in 15 mammaplasty samples with that in 4 ductal carcinoma samples, and 1 dissected epithelial sample. The control epithelial sample contained CYP1A1, CYP1B1, CYP2A6, CYP2B6, CYP2E1, CYP2C, CYP3A, and CYP19 (aromatase). These forms were present also in the reduction samples, with CYP2E1 and CYP1B1 being detected in all samples. In addition, the reduction samples contained CYP4A11 and CYP2D6. CYP2B6, CYP2D6, and 2C were more easily detected in the carcinoma samples, thus differing from the reduction samples and the epithelial sample. CYP was isolated from the reduction samples, and the P450 profiles on Western blots were compared with the RT-PCR results. In general, there was good agreement between the two methods, and the discrepancies found were probably caused by lack of specific antibodies. We conclude that much useful information about P450 in the breast can be obtained from reduction mammaplasty samples.

Adolescent↗
PubMed1998

The dynamic response of human subjects while seated in car seats.

A pendulum impact method was used to establish the dynamic response of the seated subject. Threaded K wires were placed in the L3 spinous process. The gain and phase angle between the platform and the vertebra were established. The response of the subject was observed while seated on a platform and a variety of other seats. The seats were found to be very important in the attenuation of the impulse, leading to a higher transmissibility. Clinical Relevance Skeletal impact through the lower extremity is quite common in many occupations. The importance of posture and seat design in attenuation of impulses has been established.

Acceleration↗
PubMed1997

The upper extremity attenuates intermediate frequency vibrations.

Vibration is related to reports of low back pain; however the biomechanics of vibration transmission through the hand-arm system has not been previously studied. Vibration was recorded on an accelerometer mounted to a pin percutaneously imbedded in the spinous process of L4 of five human subjects. The energy was applied through an impact via a pendulum. The subjects adopted an erect, relaxed or bent knee posture. The first resonance was 4-6 Hz and the second at 9-14 Hz. With the knee bent, the signal was almost completely attenuated. If the impact was applied through a handle and the hand-arm system there was complete attenuation.

Acceleration↗