Search PubMed⌕ Search

Biomedical subjects

M Magnusson

Publications and source records attributed to M Magnusson.

At least 37 records · Page 2Linked to original sources
PubMed2002

Neck vibration causes short-latency electromyographic activation of lower leg muscles in postural reactions of the standing human.

To study how quickly cervical proprioceptive information induced muscular responses in the lower leg to control posture in the standing human we investigated lower leg muscle electromyography and force-plate data from 10 healthy normal subjects, when perturbed by posterior neck muscle vibration. At the onset of vibration the tibialis anterior muscle was activated at latencies of 70-100 ms whilst the triceps surae muscle was inhibited at the same latencies. At offset the opposite pattern was observed. These findings suggest that a short-latency integrative system, rather than a direct reflex, mediates the cervical influence on posture. The short latencies also imply that activation of postural muscles in response to vibration towards the neck muscles occurs faster than would be expected if it was caused only by a perceptive illusion of movement.

Adult↗
PubMed2002

On-line monitoring of solutes in dialysate using absorption of ultraviolet radiation: technique description.

PURPOSE: The aim of this work was to describe a new optical method for monitoring solutes in a spent dialysate using absorption of UV radiation. METHOD: The method utilises UV-absorbance determined in the spent dialysate using a spectrophotometrical set-up. Measurements were performed both on collected dialysate samples and on-line. During on-line monitoring, a spectrophotometer was connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through a specially-designed cuvette for optical single-wavelength measurements. The concentrations of several substances of various molecular sizes, electrical charge, transport mechanism, etc. were determined in the dialysate and in the blood using standard laboratory techniques. The correlation coefficient between UV-absorbance of the spent dialysate and concentration of the substances in the spent dialysate and in the blood was calculated from data based on the collected samples. RESULTS: The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single hemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicate a very good correlation between UV-absorbance and several small waste solutes removed such as urea, creatinine and uric acid in the spent dialysate and in the blood for every individual treatment at a fixed wavelength of 285 nm. Moreover, a good correlation between the UV-absorbance and substances like potassium, phosphate and beta2-microglobulin was obtained. The lowest correlation was achieved for sodium, calcium, glucose, vitamin B12 and albumin. CONCLUSIONS: A technique for on-line monitoring of solutes in the spent dialysate utilising the UV-absorbance was developed. On-line monitoring during a single hemodialysis session exploiting UV-absorbance represents a possibility to follow a single hemodialysis session continuously and monitor deviations in dialysis efficiency (e.g. changes in blood flow and clearance). The UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.

Adult↗
PubMed2001

Dominant paternal transmission of Cornelia de Lange syndrome: a new case and review of 25 previously reported familial recurrences.

The Cornelia de Lange syndrome (CdLS) is an autosomal dominant multisystem disorder characterized by somatic and cognitive retardation, characteristic facial features, limb abnormalities, hearing loss, and other organ system involvement. The vast majority of cases (99%) are sporadic, with rare familial occurrences having been reported. Most individuals with CdLS do not reproduce as a result of the severity of the disorder. Maternal transmission has been well documented, as have several cases of multiple-affected children being born to apparently unaffected parents. Paternal transmission has rarely been reported. A case is reported here of a father with classic features of CdLS with a similarly affected daughter. A review of the reported familial cases of CdLS is summarized.

Adult↗
PubMed2001

The Boeing prospective study and beyond.

STUDY DESIGN: The Boeing prospective study was reviewed. The Boeing prospective study, comprising two articles, was a large field study that explored why workers would or would not report occupational back pain problems. OBJECTIVES: The most immediate objective was to determine the extent to which conclusions drawn from the Boeing prospective study withstand critical examination. The ultimate purpose of this review was to develop guidelines for field studies of back pain in industry. SUMMARY OF BACKGROUND DATA: For more than a century, researchers have noted great variability among individuals in the reporting of back pain, but the explanations posed for this variability have been inconsistent. Because findings gain credibility roughly to the extent that they bear on the world outside the laboratory, field studies in particular hold great potential for clarifying the underlying explanation for individual variability in back pain reporting. The Boeing prospective study was a large and ambitious field study that examined this issue. METHODS: The Boeing prospective study was examined through the lens of research conducted since it was published. The review used both the methodological and substantive literature. RESULTS: The Boeing prospective study, based on a minority of workers originally solicited to participate in it (33-41%), accounted for 7% of the variation in why workers would or would not report a back pain problem. A number of issues that may have biased its results toward the null are examined. CONCLUSIONS: The highlighting of the Boeing prospective study's limitations may be instructive not so much to criticize this one particular study but, rather, to anticipate problems that in general may be encountered in field studies of back pain in industry. Looking beyond the Boeing prospective study, the following guidelines for the conduct of such studies may be proposed: 1) Study designs should be based on explanations from which testable hypotheses may be derived; 2) Subgroups within the more general category of "back pain" should be delineated; 3) Both occupational exposures and psychosocial factors should be entered into the analysis; 4) Factors not apparent at the workplace should be considered; 5. Abstracts of articles should be carefully crafted.

Back Pain↗
PubMed2001

pap genotype and P fimbrial expression in Escherichia coli causing bacteremic and nonbacteremic febrile urinary tract infection.

Escherichia coli strains from patients with febrile urinary tract infections (n=73) were examined for pap genotype and P fimbrial expression in relation to bacteremia and patients' background variables. Most isolates were pap(+) by DNA hybridization (n=51), and 36 were papG(IA2)(+) and 18 prsG(J96)(+) by polymerase chain reaction. The pap and papG genotypes of the infecting strain were shown to vary with host compromise, sex, and age. Bacteremia in noncompromised patients was caused by papG(IA2)(+) strains, but compromised hosts carried a mixture of papG(IA2)(+), prsG(J96)(+), and pap(-) strains. Women of all ages were infected with papG(IA2)(+) strains. Infected men carried prsG(J96)(+) or pap(-) strains and were older, and most had compromising conditions. papG(IA2)(+) strains predominated among patients with medical illness, whereas prsG(J96)(+) strains predominated among patients with urinary tract abnormalities. These findings emphasize the strong influence of host factors on the selection of E. coli strains causing febrile urinary tract infections.

Adhesins, Bacterial↗
PubMed2001

The plasmid pcDNA3 differentially induces production of interferon-alpha and interleukin-6 in cultures of porcine leukocytes.

An adjuvant effect of invertebrate DNA has been attributed to its relative high frequency of unmethylated CpG dinucleotides. Here we describe the interferon-alpha (IFN-alpha) and interleukin-6 (IL-6) inducing properties of a commonly used eukaryotic expression vector, pcDNA3, in porcine leukocytes. The magnitude of the cytokine response was compared to that induced by the synthetic ds RNA analogue poly(I):poly(C), inactivated preparations of Aujeszky's disease virus (ADV) and the Gram-negative bacteria Actinobacillus pleuropneumoniae. The plasmid, as well as poly(I):poly(C), required lipofectin to induce IFN-alpha production whereas both preparations induced IL-6 irrespective of preincubation with lipofectin. However, the nucleic acid-induced levels of IL-6 were low compared to those induced by A. pleuropneumoniae. The IFN-alpha response elicited by pcDNA3 in the presence of lipofectin was as high as, or higher than that induced by ADV. Interestingly, also A. pleuropneumoniae induced a substantial production of IFN-alpha when preincubated with lipofectin. Plasmid expression was not necessary for induction of IFN-alpha. Furthermore, the IFN-alpha inducing capacity of pcDNA3 was not reduced when the two predicted immunostimulatory sequences 5'AACGTT3' were deleted. Nor did the ability of the plasmid to induce IFN-alpha production decrease when the ampicillin resistance (ampR) gene was replaced with the kanamycin resistance (kanR) gene. However, methylation of all cytidines in CpG dinucleotides of pcDNA3 abolished the IFN-alpha inducing capacity. These in vitro results indicate an immunomodulatory role of bacterial DNA also in the pig. Unmethylated CpG dinucleotides are crucial for induction of IFN-alpha by the plasmid, but other CpG motifs than those within the 5'AACGTT3' sequences of the ampR gene contribute to this induction in porcine cells.

Actinobacillus pleuropneumoniae↗
PubMed2001

Multi-stimulus multi-response posturography.

In this study a method for the analysis of simultaneous multiple measurements of kinematics and stabilizing forces related to human postural dynamics is proposed. Each subject in a group of normal subjects (n=10) was tested with eyes-open and eyes-closed with simultaneous but uncorrelated vestibular and proprioceptive stimuli in order to investigate the contributions of individual sensory feedback loops. Statistical analysis was made by means of multi-input multi-output identification of a transfer function from stimuli to stabilizing forces of the feet and the resulting body position, the transfer function being compatible with a biomechanical model formulated as a stabilized segmented inverted pendulum subject to feedback of body sway and position. Each individual model estimated is effective in predicting a subject's response to new stimuli and in describing the interacting effects of stimuli on body kinetics. The proposed methodology responds to the current needs of data analysis of multi-stimulus multi-response experiments.

Adolescent↗
PubMed2001

The effectiveness of routine health examinations at 2, 6, 9 and 12 months of age: experiences based on data from a Swedish county.

AIM: The aim of this study was to elucidate the role of health surveillance for infants during the first year of life in detecting severe health problems. Two central questions were addressed: (1) what health problems were detected by routine health examinations at the Child Health Centre at the 2-, 6- and 12-month check-ups by a physician and at the 9-month check-up by a nurse; and (2) to what extent did the health examinations contribute to early identification of children with following key abnormalities: congenital heart disease, congenital dislocation of the hip, abnormalities as registered at the habilitation centre and severe hearing impairments? MATERIAL AND INCLUSION CRITERIA: The study population included all children in Uppsala county, born January 1995 to October 1996, who had participated in at least one of the four health check-ups. There were 3107-3487 children in the respective check-ups. METHOD: Data from a county health register as well as child health records and information regarding referrals were analysed to categorize the health problems by type, severity and action taken. Data on children with key abnormalities were obtained from specialist units. RESULTS: The rate of suspected new health problems varied between 1.9% and 2.8% at the respective check-ups. Of the new problems detected by the physician, 21%-36% were false-positive, 34%-44% were minor and 10%-15% were moderate. Only two severe health problems were detected among all the children during the four check-ups. Of all key abnormalities, 20% were detected by way of child health surveillance during the first year of life. IMPLICATIONS: Severe health problems and key abnormalities in infants were detected only to a limited extent through routine health examinations at 2, 6, 9 and 12 months of age. The minor and moderate problems detected justify a health surveillance programme, but the organization and content of the programme could be reconsidered.

Child Health Services↗
PubMed2001

Importance of CpG dinucleotides in activation of natural IFN-alpha-producing cells by a lupus-related oligodeoxynucleotide.

The oligodeoxyribonucleotide (ODN) 5'-TTTTCAATTCGAAGATGAAT-3' (ODN H), identified in systemic lupus erythematosus (SLE) serum, induced the production of interferon (IFN)-alpha in human peripheral blood mononuclear cells (PBMC) when combined with lipofectin. Flow cytometric analysis with staining for surface antigens and intracellular IFN-alpha, showed that the IFN-alpha-producing cells (IPC) were the natural IPC, also termed type 2 dendritic cell precursors (pDC2) or plasmacytoid monocytes. The importance of unmethylated CpG dinucleotides for the interferogenic activity of ODN was studied. Methylation of CpG impaired the activity of single-stranded (ss) ODN H, but increased that of the complementary ssODN I. Furthermore, CpG-methylated double-stranded (ds) ODN Hmet-Imet lost, but hemimethylated dsODN H-Imet retained interferogenic activity. Inversion of the CpG to GpC had no effect on the interferogenic activity of ssODN H, increased that of ssODN I, however abolished the activity of dsODN H-I. Alteration of the CpG in ODN H to ApG and in the ODN I to CpT destroyed their activity. The induction of IFN-alpha is therefore sequence-specific, but unmethylated CpGs are not always required, especially not in ssODNs. Interferogenic DNA sequences could therefore be more frequent in eukaryotic genomes than previously thought and their capacity to activate natural IPC may have implications for immune responses to microbial antigens and nuclear autoantigens.

Antigens↗
PubMed2001

Effect of chronic renal failure on bone turnover and bone alkaline phosphatase isoforms.

BACKGROUND: Biochemical markers of bone turnover are used to monitor metabolic bone disease associated with renal failure. We have applied a comprehensive panel of markers to patients with chronic renal failure (CRF), with particular focus on the isoforms of bone alkaline phosphatase (BALP). METHODS: Twenty CRF patients undergoing hemodialysis (N = 9) and peritoneal dialysis (N = 11) were measured for serum parathyroid hormone (PTH), osteocalcin, total ALP, and four BALP isoforms (B/I, B1x, B1, and B2) by high-performance liquid chromatography. These BALP isoforms were also compared with BALP measured by three commercial immunoassays (Alkphase-B, Tandem-R Ostase, and Tandem-MP Ostase). Type I collagen turnover was assessed by serum samples using the type I procollagen intact amino- and carboxy-terminal propeptides (PINP and PICP) and two fragments (ICTP and CrossLaps) derived from the carboxy-terminal telopeptide of mature matrix collagen by different degradative pathways. RESULTS: Mean levels of bone turnover markers were elevated in CRF, with marked increases in those markers, osteocalcin, ICTP, and CrossLaps, cleared by the kidney. Total ALP activities were increased corresponding to elevated B/I and B2 isoform levels. The B1 isoform level was not significantly different from healthy controls. B1x was detected in 60% of the patients but was not resolved in healthy individuals. Kendall's tau rank correlation showed that B1x correlated significantly (P < 0.05) with B1 (0.53) and PINP (0.55), and was the only marker to correlate with PTH (0.49). B1x was not significantly correlated with any of the commercial BALP immunoassays. Interestingly, the immunoassay calibrators contained high activities of the B/I peak (39 to 80%) compared with human serum (4%). CONCLUSION: There are selective differences between the BALP isoforms in CRF compared with healthy adults. The commercial BALP immunoassays are comparable with each other but are unable to distinguish the BALP isoform-specific differences in CRF patients.

Adult↗
PubMed2001

Changes in postural control in healthy elderly subjects are related to vibration sensation, vision and vestibular asymmetry.

The aim of this study was to analyze the composition of sway in adults and "healthy" elderly people and to evaluate the influence of vibration sensation and asymmetric vestibular function on the sway pattern. Ten adults with a mean age of 37.5 years and 40 healthy senior citizens with a mean age of 74.6 years living independently in the community were studied. Vibration-induced body sway was measured on a force platform. The sway was analyzed and separated into its high and low frequency components above and below 0.1 Hz, respectively. Additionally the elderly subjects were observed for the occurrence of spontaneous gaze and head shake-induced nystagmus using infrared charge-coupled device cameras and the vibration perception in the lower limbs was tested with a tuning fork. Vibration perception was the major determinant for postural control in the elderly subjects. Postural control among the elderly subjects with intact vibration perception in their lower limbs was very similar to that of the adults. The elderly subjects with impaired vibration sensation had increased high frequency sway compared to adults and the elderly subjects with intact sensation. Regardless of the strong influence of vibration sensation on postural control, asymmetric vestibular function might also be a contributing factor to postural instability in the elderly. Age per se had little effect on the outcome of the tests except that the elderly subjects had diminished ability to use visual cues to reduce postural sway. We concluded that sensory status in the lower limbs is of utmost importance for postural control in the elderly. Rehabilitation programs for senior citizens should therefore include exercises to preserve recognition of body motion by the lower limbs. Exercises to facilitate vestibular compensation could be useful for elderly people with vestibular dysfunction.

Adult↗
PubMed2001

Observation of vestibular asymmetry in a majority of patients over 50 years with fall-related wrist fractures.

Previously [The abstract has been shortened somewhat, and the headings removed, in order to conform to journal style], we have observed vestibular asymmetry in about one-third of healthy senior citizens and in about two-thirds of subjects with previous hip fractures and no other significant ailments. Wrist fractures are considered a harbinger of hip fractures. If vestibular asymmetry is correlated with falls and fractures among the elderly then it should also be reflected among subjects with wrist fractures. Sixty-six consecutive patients (mean age 67.8 years) who had sustained a fall-related wrist fracture during a 10-month period were included in the study. The frequency of head shake nystagmus among the patients was compared to that found among 49 healthy senior citizens (mean age 74.9 years). Nystagmus after head shaking, indicating asymmetric vestibular function, was found in 50 participants (76%) (p <0.001). Thirty-eight of these were graded with distinct or prominent nystagmus responses. Sixty percent of the subjects with horizontal nystagmus had a wrist fracture coinciding with the slow phase of nystagmus. Twenty-three subjects reported 30 previous fall-related fractures during the previous 10 years. Subjects with nystagmus after head shaking sustained 26 of these fractures. The frequency of signs of vestibular asymmetry was significantly higher (p < 0.001) among the subjects than among healthy senior citizens. These findings suggest that an asymmetric vestibular function could be an epidemiologically important contributory factor to falls and wrist fractures among the elderly population.

Accidental Falls↗
PubMed2000

The effects of galvanic stimulation on the human vestibulo-ocular reflex.

We studied the effects of 5 mA bilateral or unilateral, bipolar or monopolar, galvanic stimulation on the horizontal vestibulo-ocular reflex (hVOR) in six normal subjects during 0.01, 0.05, 0.1, 0.5 and 1 Hz yaw rotations and in two subjects during high-acceleration, low-amplitude yaw head rotations (head impulses). Bipolar galvanic stimulation induced horizontal nystagmus in all subjects and an asymmetry of the hVOR only during rotations below 0.1 Hz. Monopolar stimulation had no significant effect. The findings suggest that in humans galvanic stimulation affects those primary horizontal semicircular canal neurons that mediate the hVOR via indirect pathways through the velocity storage mechanism.

Acceleration↗
PubMed2000

Time structure of behavioral patterns related to feed pecking in chicks.

Nonrandom time patterns of pecking acts by 16 chicks were detected using the software Theme during three videotaped pecking sessions (M, C, and A). At 15 days of age pecking session, M (mash) was recorded when chicks ate a mash diet. Pecking session C (change) at 16 or 17 days of age was recorded immediately after the change of the diet to pellets presented either as regular cylinders (P) to eight chicks, or as semiovoid (Po) to eight other chicks. Pecking session A (adapted) was recorded 5 or 6 days after adaptation to P and Po. Successful (consumatory) pecks were 72%, 52%, and 61% of all pecks for sessions M, C, and A, respectively. The head of the chicks remained in a steady position between two consecutive pecks for a longer period during C (65% of the time) than M and A (54%). During C, the pecking rate was less for P (0.54 pecks/s) than for Po (0.79 pecks/s). Two consistent time patterns involving four acts frequently observed were: head rotation (or exploratory peck)-->head in steady position-->consumatory peck-->head in steady position with jaw movements. Time intervals within a pattern were stable throughout sessions. However, the proportion of synchronized (included in a pattern) vs. nonsynchronized (not included in a pattern) acts decreased immediately after the change of feed form (session C). These results suggest that pecking at feed is composed of two distinct sets of acts: consistently organized patterns little affected by the form of the pecked particles and nonsynchronized acts that may be involved in sensory information.

Aging↗
PubMed2000

Methods for evaluation of postural control adaptation.

New methods were developed to determine the dynamic changes of postural control during the initial exposure to large perturbances of stance. The adjustments of postural control over time in measured anteroposterior torque, were investigated in ten normal subjects. Perturbations of stance were evoked by two high intensity vibrators applying pseudorandom stimulation either to the calf muscles or the paravertebral muscles of the neck. The new methods use a system identification approach, which distinguishes between feedback control, adaptation of postural responses and adaptation to stimulus. This approach makes it possible to quantify motion dynamics and complexity, stimulus impact and adjustments of postural control. Quantification of the different adaptive responses could be useful for diagnostic purposes, in evaluating treatment efficacy and patient progress in rehabilitation programs.

Adaptation, Physiological↗
PubMed2000

Biomechanic evaluation of the Rola Stretcher as a passive distraction device.

INTRODUCTION: Many devices have been marketed claiming to increase the mobility of the articulations of the spine with active or passive distraction. In this study, the Rola Stretcher (Unique Relief, Inc, Davenport, Iowa) and an earlier version, the True Back II (True Back, Inc, Clearwater, Fla), were evaluated to see if they have a measurable biomechanic effect on the spine. METHODS: Two studies were conducted, each with 6 male participants and 6 female participants, using a stadiometer to accurately measure a person's sitting height. The increase in sitting height after using the True Back II or Rola Stretcher for 10 minutes was compared with that after lying supine for 10 minutes. A third intervention, a firm foam block cut to the same size and shape as the True Back II, was also used in this study. RESULTS: The Rola Stretcher had a significantly greater lengthening effect on the spine compared with supine rest (P <0050). The True Back II had a similar but lesser effect (P <.0509). Women demonstrated a greater height gain than men. CONCLUSION: The True Back II and the Rola Stretcher in particular appear to lengthen the spine after a single use of 10 minutes. The observed discrepancy between the effects in men and women may be an experimental artifact occurring as a result of less effective resetting of the posturing mechanisms in men compared with women. A trend showed the Rola Stretcher to be more effective than the foam block.

Adult↗
PubMed2000

Direction of galvanically-induced vestibulo-postural responses during active and passive neck torsion.

The direction of a postural response induced by galvanic vestibular stimulation depends on the head and trunk position. The relative importance of afferent information (proprioception) and efferent motor command/corollary discharge is unknown. We studied the direction of body sway evoked by galvanic vestibular stimulation in 9 healthy subjects during active and passive head positioning at 0 degrees frontal position, 35 degrees to the left, and 75 degrees to the right, using a custom-built collar. At 0 degrees and 75 degrees there were no significant differences in sway direction between active and passive head positioning. The galvanic stimulation invoked sway toward the anode, mainly in the inter-aural direction. The sway direction differed significantly between active and passive positioning at 35 degrees to the side (p < 0.05). When the head was actively kept in this position, the body sway was mainly in an inter-aural direction. The sway shifted to a naso-occipital direction when the head was passively positioned at 35 degrees. Our results indicate that the afferent proprioceptive information has the largest influence on the direction of the galvanically-induced postural response, although some dependence on efferent motor commands and non-linear cervical proprioception cannot be ruled out entirely.

Adult↗