Biomedical subjects

T Oberg

Publications and source records attributed to T Oberg.

At least 19 recordsLinked to original sources

PubMed2007

Metal catalyzed formation of chlorinated aromatic compounds: a study of the correlation pattern in incinerator fly ash.

Chlorinated aromatics are unintentionally formed and released from combustion and other thermal processes involving organic matter and chlorine. The catalytic activity of incinerator fly ash in the low-temperature formation of chlorinated aromatics has been demonstrated in both laboratory experiments and full-scale trials. Copper has been shown to be an effective catalyst, but several other transition metals possess a similar activity. Here results are reported from a series of full-scale combustion trials with different fractions of household and industrial wastes, with waste from forestry as a reference fuel. The composition of elements and chlorinated aromatics in the fly ash was evaluated with principal component analysis and partial least squares regression. The observed correlation pattern indicates that metals other than copper are of equal importance for the catalytic activity. Chromium and nickel are two of these metals, which may contribute to the de novo formation of chlorinated benzenes, phenols, PCDD and PCDF.

Air Pollutants↗

PubMed2005

Serum C-reactive protein in elderly men and women: association with mortality, morbidity and various biochemical values.

OBJECTIVE: The primary aim of this study was to define the distribution and the prognostic value of serum C-reactive protein (s-CRP) measured by a high-sensitivity method in elderly subjects of both genders with special reference to the distribution below 10 mg/l. As a secondary aim, a possible gender difference of s-CRP was examined. MATERIAL AND METHODS: Baseline s-CRP was described in a population-based sample of opposite-sex, twin-pairs (197 F, 189 M available for blood-sampling) aged 71-80 years (mean age 74.5 years), considering mortality through the next 4 years, morbidity (myocardial infarction, angina pectoris, congestive heart failure, arterial hypertension, venous thromboembolism, stroke, diabetes, gout, psoriasis, rheumatoid arthritis) before and after blood sampling, biochemical values (serum levels of urate, urea, ApoA1, ApoB, folate, FSH, LH, oestradiol, progesterone, testosterone, cortisol) and anthropometric measurements (body mass index (BMI), circumference of waist, buttocks and hips). RESULTS: The level of s-CRP did not deviate substantially from what has been reported for younger subjects. Higher values indicated an increased risk of cardiovascular morbidity and diabetes in women but not in men. The s-CRP level was associated with serum levels of urate, progesterone, folate, ApoA1, ApoB and the quotient ApoB/ApoA1 as well as with BMI and waist circumference. CONCLUSIONS: For the 71-80 years age group, s-CRP below the 80th percentile (4.3 mg/l) seems to have prognostic capacity mainly in women. The highest association with mortality as well as with cardiovascular diseases, diabetes and rheumatoid arthritis is found for s-CRP above 10 mg/l, which is the arbitrary lower level for the earlier routine low-sensitivity s-CRP methods. The association of s-CRP with serum urate, folate and the ApoB/ApoA1 quotient should be considered.

Aged↗

PubMed2004

From major amputation to prosthetic outcome: a prospective study of 190 patients in a defined population.

In this prospective study, the overall treatment and outcome of patients that underwent major lower limb amputation in a defined population is described. The study was performed over a five year period in the Health Care District of North-East Skåne, Sweden. Some 190 patients, permanent inhabitants of the Health Care District, underwent major lower limb amputation. Sixteen (16) of these patients had amputations before the study started and went through late second leg amputation during the period. One hundred and seventy four (174) patients had primary major amputation. Seventy nine (79) were men and 95 were women, with a median age of 81. The re-amputation rate was 17% although the primary knee preservation ratio was as high as 3.0:1. Rigid dressing was the standard method following trans-tibial amputation and was used for 5-7 days. ICEROSS silicone liner was used for compression therapy in 90% of all cases that resulted in delivery of a prosthesis. Prostheses were delivered to 43% of all patients with primary amputations. These patients spent a median of 13 days at the orthopaedic clinic. 55 days at the rehabilitation unit. Pressure casting was used as a standard method in the production of the prosthetic socket. ICEX carbon-fibre socket was used in 52%. New procedures, treatments and techniques were introduced, standardised and evaluated whilst the routines in the hospital were reorganised. In this way, a system has been implemented that better guarantees the outcome of the whole procedure and the service received by this category of patients.

Aged↗

PubMed2003

Chlorinated aromatics from combustion: influence of chlorine, combustion conditions, and catalytic activity.

Research on the formation of chlorinated aromatics in combustion processes has mainly taken place in the laboratory. Previous attempts to correlate observation data from commercial plants have been inconclusive. This study reports on the outcome of an industrial experiment in a full-scale afterburner. The influence of chlorine input, combustion temperature, and catalytic activity was investigated in a factorial design with two blocks. Polychlorinated benzenes, dibenzo-p-dioxins, and dibenzofurans were formed both at combustion temperatures and below 400 degrees C. The results show that all three experimental factors have statistically significant impact on the formation and release of these toxic byproducts. The quantitative dependence between chlorine input and the occurrence of chlorinated aromatics is of particular interest due to previous controversy. The purpose with this study was to ensure that the installation of a boiler for energy recovery would not cause elevated emissions of chlorinated aromatics. The experiment demonstrated that this risk is probably low, since the presence of catalytic material or an increase in chlorine input is required for this to happen. A general conclusion was that industrial experimentation employing the principles of statistical design could improve the validity in recommendations regarding commercial plant operation.

Air Pollutants↗

PubMed1999

Segmental movements of the spine during treadmill walking with normal speed.

OBJECTIVE: The aim of the present work is to investigate the segmental movement patterns of the spine during normal treadmill gait. DESIGN: The spine movement during treadmill gait of ten healthy subjects (five men and five women) has been investigated using an optoelectronic measuring system. METHODS: The spine was divided into seven segments, from C(7) to S(2). The subjects walked with their normal speed. All data were normalized to per cent of the gait cycle. The normal patterns of the spine segment movements were found in the sagittal and the frontal planes. RESULTS: The behaviour of the spine can be described as the motion of a stiff element with superimposed small, inter-segmental movements. These small inter-segmental movements were found both in the sagittal and the frontal planes. CONCLUSIONS: The small inter-segmental movements could play an important role in the reduction of the energy consumption during gait and in maintenance of the equilibrium. RELEVANCE: Any disability affecting the spine should result in changing spine movement pattern during gait, thus changing the overall gait pattern. Therefore, treatment and rehabilitation should not discard the influence of the spine malfunctioning, regardless of its nature.

Adult↗

PubMed1999

Relaxed versus activated stump muscles during casting for trans-tibial prostheses.

In prosthetic practice, the question often arises as to whether the hand cast should be made from a contracted or from a non-contracted amputation stump. To elucidate this question, the authors have performed a study to quantify the volume difference between these 2 conditions, and to relate the differences to prosthetic fitting. Sixteen (16) trans-tibial amputees participated in the study. All of them were fitted with an ICEROSS silicone socket. Electromyographic studies, with electrodes attached to the anterior tibial and medial gastrocnemius muscles, were carried out to determine muscle contraction levels. Volume determinations were made with the CAPOD laser scanning system. Measurements were performed with and without the silicone liner on the stump. Without a silicone liner, the volume of the stump increased by 5.8% (SD=5.3) as the muscles contracted. This increase was statistically significant. With the liner donned the volume increased 3.5% (SD=3.3). This increase was also statistically significant. The volume of the prosthetic socket was also compared with the stump volume with a silicone liner on. For the relaxed stump, the difference was 1.8% (SD=10.1), and for the contracted stump -1.7% (SD=11.3). Neither difference was statistically significant. The importance of these volume changes and how they influence stiffness of the coupling between the stump and the socket are discussed. It is concluded, that the observed difference in volume between a contracted and a non-contracted stump are large enough to be considered by the prosthetist in his decision on how to make a hand cast.

Aged↗

PubMed1998

Morphological changes during early trans-tibial prosthetic fitting.

Morphological changes in the amputation stump may have serious implications regarding the suspension and fit of the prosthetic socket. In an earlier study (Lilja and Oberg, 1997) the authors have shown that the volume of the trans-tibial amputation stump decreases according to a negative power function after amputation, and that the stump volume does not stabilise until four months after the operation. In the present study, Magnetic Resonance Imaging (MRI) technique was used to examine morphological changes in the amputation stump after trans-tibial amputation in a small number of cases. The authors expected to find a decrease in the cross-sectional area of the stump and of the separate muscles similar to the findings in earlier studies. However, two different patterns were found. The cross-sectional area of the entire stump as well as that of the medial muscle group changed according to the authors' hypothesis, i.e. an initial fast decrease, followed by a more moderate decrease of the area. In the lateral muscle group another pattern was found. After an initial rapid decrease the area increased, sometimes to a magnitude larger than the initial value. After the amputation the lateral muscle group may acquire a new function, contributing to the suspension of the socket. Despite the limited number of patients, this study presents findings which may be important in the clinical fitting of trans-tibial prostheses.

Aged↗

PubMed1998

Accuracy and precision of volumetric determinations using two commercial CAD systems for prosthetics: a technical note.

The aim of this study was to evaluate the validity and reliability of volume determinations using the commercially available Seattle ShapeMaker CAD/CAM system for production of prosthetic sockets and to compare it with the commercially available CAPOD system. We used three types of reference objects for volumetric determinations: steel tubes, plaster of Paris casts, and residual limb models. Three different sizes were examined for each type of object. Volume measurements with the two CAD/CAM systems were compared with measurements obtained by water filling, water immersion, or mathematical calculation (tubes only). We found an inconsistent systematic error of less than 3.1% for ShapeMaker and no systematic error for CAPOD. Random errors, represented by the coefficient of variation, were below 1.3% for the ShapeMaker and, in most cases, below 0.4% for the CAPOD. Theoretical changes in volume of 2.6% and 0.8% are possible to detect with these CAD/CAM systems. In our opinion, both systems have sufficient precision for routine clinical use in prosthetics and orthotics. However, in our study, the ShapeMaker committed larger random and systematic errors than CAPOD. This means that, according to our study, CAPOD offers the best possibility to determine and detect small changes in residual limb volume as a function of time.

Artificial Limbs↗

PubMed1996

Worse functional status among old people when admitted for arthroplasty--an evaluation with a new assessment system.

The aim of this study was to investigate whether there is a difference in functional status between younger and elderly people referred to an orthopaedic clinic for total joint replacement. A total of 709 patients with osteoarthritis of the hip or knee (aged 27-91 years) and 42 healthy controls (aged 42-83 years) were examined with a new Functional Assessment System (FAS) for lower extremity dysfunction. Age effects were explored by one-way analysis of variance. Older people showed higher dysfunction scores in almost all variables, with the exception of pain, where there was an inverse relationship, i.e, old people had lower disability scores. This age-related increase in disability scores was not observed in the control group. Old people seem to be referred for joint replacement on different grounds from those of younger people, despite the fact that age was not included in the criteria for arthroplasty. The results may indicate a hidden, age-related criterion in the selection of patients for arthroplasty. Different interpretations are discussed.

Activities of Daily Living↗

PubMed1995

Volumetric determinations with CAD/CAM in prosthetics and orthotics: errors of measurement.

During the next decade CAD/CAM technique will probably become routine in prosthetics and orthotics, not only as a complement to manual techniques, but also introducing new possibilities. However, even complex and sophisticated techniques have errors of measurement that must be considered. Such errors are of two principal kinds: systematic errors and random errors. In this study we have evaluated the Swedish CAPOD system with respect to volumetric determinations. We used two types of reference objects for volume determinations: cylinders and amputation residual limb models. Three different sizes were examined of each type of object. Volume measurements with CAPOD were compared with volumes obtained by water immersion or mathematical calculation (cylinders only). We found a constant, linear systematic error of +2.5%. Such an error can easily be corrected for. The random error, represented by the coefficient of variation, was 0.5%, which means that there is a theoretical possibility to detect volume changes exceeding 1%. We consider the precision sufficient for clinical practice in prosthetics and orthotics. Biological variations due to soft tissue deformation must be added on top of these errors. Such deformations were not evaluated in this study.

Artificial Limbs↗

PubMed1994

Subjective and objective evaluation of shoulder muscle fatigue.

In order to relate EMG signs of localized muscle fatigue to subjectively perceived muscle fatigue, a study was undertaken on 20 healthy volunteers exposing their right trapezius muscle by raising the arm to 90 degrees of abduction. Every person performed two contractions: 0 kg hand load during 5 min and 2 kg hand load during 2.5 min. Surface EMG was recorded and analysed with respect to RMS amplitude and mean power frequency (MPF). Subjective muscle fatigue was estimated with a psychophysical rating scale (Borg's CR-10 Scale). At high load level we found a significant correlation between MPF and the CR-scores (r = -0.46), but at low load level there was no correlation. At high load level there was a linear decrease of MPF with increasing load dose, but at low load level the MPF did not change, despite significant subjective fatigue. There was a linear rise of the CR-score with increasing load dose, more pronounced at high load level. It was concluded, that at low load levels common in working life, MPF and subjective scores seem to provide different fatigue information. Moreover, the MPF did not seem to work as a valid estimator of muscle fatigue at this low load level. Caution is recommended if it is to be used in static low-load situations.

Adult↗

PubMed1994

Validity and reliability of a new assessment of lower-extremity dysfunction.

BACKGROUND AND PURPOSE: A 20-variable assessment system for evaluation of lower-extremity dysfunction has been constructed with special consideration of the needs of the physical therapist. The variables are classified into five subgroups: hip impairment, knee impairment, physical disability, social disability, and pain. SUBJECTS: One hundred five patients with osteoarthrosis of the hip and knee, all accepted for total joint replacement arthroplasty, were tested. The mean age of the patients was 69 years (SD = 9.0, range = 46-91). METHODS: The original grouping of the variables was analyzed for content validity with a factor analysis. The results from a subgroup of 42 patients were tested for intertester reliability with the Goodman-Kruskal gamma coefficient. RESULTS: The factor analysis indicated a factor solution consistent with the primary grouping except for two variables. The correlation between two independent physical therapists was .99 to 1.00 for different variables, indicating excellent intertester reliability. CONCLUSION AND DISCUSSION: In the authors' opinion, the new assessment system provides a reasonably valid, reliable, inexpensive, and easy-to-use measurement and fulfills the needs of the physical therapist for functional evaluation of the lower extremity.

Activities of Daily Living↗

PubMed1994

Physical training of children with juvenile chronic arthritis. Effects on force, endurance and EMG response to localized muscle fatigue.

We examined force, endurance and the electromyographic response to muscle fatigue in ten children with juvenile chronic arthritis (JCA) and ten age-matched healthy controls before and after physical training. Our main finding was a reduced electromyographic response to localized muscle fatigue in the patient group. After training there was a tendency towards a normalized response pattern. A possible explanation may be selective type-II muscle fiber atrophy, and recovery of these fibers after training.

Adolescent↗

PubMed1994

Joint angle parameters in gait: reference data for normal subjects, 10-79 years of age.

In the laboratory, gait analysis is often completed with goniometry. In a previous article (Journal of Rehabilitation Research and Development, Vol. 30 No. 2), reference data for basic gait parameters were presented. The aim of this study was to provide such reference data for joint angle parameters. Two hundred and thirty-three healthy subjects (116 men and 117 women) 10-79 years of age, were entered into the study. The measurements were made in a gait laboratory with electrogoniometers with Lamoreaux type of exoskeleton. A series of reference tables for slow, normal and fast speed are presented. Means, standard deviations, coefficients of variation, 95% confidence intervals, and 95% prediction intervals were calculated. We found minor changes with age, no differences between right and left side, significant sex differences, and significant changes with increasing gait speed. The reference data are considered valid in an indoor laboratory situation. If gait analysis is used for evaluation of disabled people, a comparison must be made with data from healthy people. This study provides such normative data for joint angle parameters.

Adolescent↗

PubMed1993

Movement of the tibial end in a PTB prosthesis socket: a sagittal X-ray study of the PTB prosthesis.

To investigate the movement of the tibial end in the sagittal plane in the PTB prosthetic socket during a gait cycle, 7 patients with a median age of 72 years were examined using X-ray technique. The gait cycle was reduced to four different static positions: heel contact, midstance, push-off and swing phase. The mean value of tibial movement in the socket in the anteroposterior direction was 2.2 cm, in proximodistal direction 2.8 cm, and the total sagittal movement during the whole gait cycle was 7.5 cm. The results indicate that one factor affecting the magnitude of the movement was the prestretching of soft tissues. All the patients who experienced a good prosthetic fitting had their soft tissues prestretched. The extreme dorsal and proximal positions of the tibial end during the gait cycle was in the swing phase position. The extreme distal position occurred somewhere between mid-stance and push-off. The extreme anterior position of the tibial end was seen during heel contact. This study has shown the magnitude of the movements in a PTB socket during a simulated gait cycle. The study has given hints on factors affecting prosthetic fitting, and further research within this field might provide indications of how to optimise socket shape to give maximal patient comfort.

Aged↗

PubMed1993

Clinical evaluation of trans-tibial prosthesis sockets: a comparison between CAD CAM and conventionally produced sockets.

This study is an evaluation, from the patient's point of view, of CAD CAM prosthesis sockets compared with conventional sockets. Twenty-two trans-tibial amputees were divided into two groups. One group was provided with a CAD CAM (CAPOD) socket, the other with a conventionally made one. After one month the groups were evaluated with regard to subjective experience, the judgement of a prosthetist and a physiotherapist, social variables and objective gait parameters. Then the groups switched over to the other type of socket, and after another month a new evaluation was performed. The study design was a single-blind study. In total 175 variables were evaluated. No difference was found between the two types of socket, except for a lower number of terry cloth stockings used in the CAD CAM socket. As the standard of conventional prosthetics in Sweden is considered to be high, the results were considered as satisfactory. The quality of the CAD CAM sockets was at least at the same level as conventionally made ones.

Aged↗

PubMed1993

Basic gait parameters: reference data for normal subjects, 10-79 years of age.

Basic gait parameters were extracted from 233 healthy subjects--116 men and 117 women, 10 to 79 years of age. The measurements were made in a gait laboratory on a 5.5 m walkway. The results are presented in a series of reference tables for slow, normal, and fast gait. Mean, standard deviation, coefficient of variation, 95% confidence intervals, and 95% prediction intervals were calculated. Significant sex differences exist in all gait parameters. In a two-way analysis of variance (ANOVA) model, there was a statistically significant age-variability for gait speed and step length at normal and fast gait, but not for step frequency. In the step length parameter there was a significant interaction effect of age and sex at normal and fast gait. The reference data are considered valid in an indoor laboratory situation.

Adolescent↗

PubMed1992

Electromyographic changes in work-related myalgia of the trapezius muscle.

In 11 patients, all women, 21-55 years of age, with unilateral work-related myalgia of the trapezius muscle, the right and left trapezius muscles were examined simultaneously for electromyogram (EMG) signs of localized muscle fatigue. All patients were tested with 0-kg hand load for 5 min, holding the arms straight at 90 degrees of elevation in the scapular plane. Only 4 of the patients tolerated exposure to higher load levels. They were tested with 1 kg hand load for 3 min and 2 kg hand load for 2 min, with a period of rest of 30 min between the trials. The EMG mean power frequency (MPF) and root mean square (rms) were calculated. Data were normalized with the initial value as a reference and regression analyses were performed. On both sides a decrease of MPF and an increase of rms were found with increasing time and load, i.e. classical EMG signs of localized muscle fatigue. Compared with the nonaffected side smaller changes were found on the affected side, possibly due to pain inhibition, impaired microcirculation and biochemical changes along the muscle fibres. At 0-kg hand load we found no change of MPF on either side despite subjective feelings of fatigue and pain. We interpreted these findings as an indication of reduced capacity of the affected trapezius muscle to sustain static load with early development of pain-associated local fatigue.

Adult↗