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Biomedical subjects

B Ekblom

Publications and source records attributed to B Ekblom.

At least 91 records · Page 5Linked to original sources
PubMed1984

Supersensitivity psychosis in schizophrenic patients after sudden clozapine withdrawal.

In two patients with chronic schizophrenia, who were on clozapine medication for more than 6 months, a sudden withdrawal of the drug resulted in a very pronounced deterioration of the psychosis within 24-48 h. The most prominent symptoms were auditory hallucinations and persecutory ideas and one patient tried to commit suicide. These observations are interpreted as supersensitivity psychoses induced by the very effective clozapine treatment.

Adult↗
PubMed1984

Muscle fibre type characteristics in endurance trained and untrained individuals.

The main fibre types of M. vastus lateralis of 10 trained or untrained male individuals (25-35 years) were quantitatively determined by morphological techniques; the fibre types being defined according to the M-band appearance. The volume density of mitochondria ( Vmit ) was higher in endurance-trained muscles. Vmit was higher in Type 1 than in Type 2 fibres, there being no difference between subtypes of Type 2 fibres. The volume density of lipid droplets ( Vli ) showed a wide range of values both with respect to degree of training and between fibre types. Z-band width was not influenced by endurance training, but was considerably larger in Type 1 than in Type 2 fibres. Discriminant analysis showed that 46% of the fibres, preclassified according to the M-band appearance, would have been correctly allocated on basis of the Vmit . The corresponding value for lipid droplets was 42% and for the Z-band width, 62%. It is concluded that Vmit is not a satisfactory criterion for discriminating between fibre types, especially between Type 2A and Type 2B in trained subjects. The study also shows that endurance training reduces the relative importance of individual-dependent factors in comparison with muscle fibre properties when concerning Vmit .

Adult↗
PubMed1984

Influence of low muscle temperature on muscle metabolism during intense dynamic exercise.

Eight males performed intense leg cycle exercise at a constant rate of work averaging 350 W, according to three different protocols: 1) "Cold exhaustive" exercise (initial muscle temperature (Tm) = 29 degrees C), 2) "Warm non-exhaustive" exercise (initial Tm = 34 degrees C) for the same period of time as in 1), and 3) "Warm exhaustive" (initial Tm = 34 degrees C). In five subjects the concentration of various muscle metabolites was determined before and immediately, 1 min, and 5 min after exercise. Blood lactate concentration was determined before and repeatedly after exercise. At low Tm maximal work time was considerably shorter for all subjects compared to normal Tm, 1.3 and 2.1 min, respectively. Comparing conditions 1) and 2) oxygen deficit and the decrease in ATP and CP content were the same in the two experiments. There was a significantly higher concentration of glucose-6-phosphate 17.6 +/- 10.1 and 8.0 +/- 6.2 mmol X kg dw-1, respectively, and a tendency to higher lactate concentration 60 +/- 36 and 33 +/- 14 mmol X kg dw-1, respectively, immediately after exercise in the "cold exhaustive exercise". Peak blood lactate concentration appeared significantly later after "cold exhaustive" exercise indicating a slower elimination rate of lactate from the muscle compared to "warm non-exhaustive" exercise. The reduction in performance observed at low Tm may partially be explained by an increased accumulation rate of lactate in four of five subjects.

Adolescent↗
PubMed1984

How to calculate human muscle fibre areas in biopsy samples--methodological considerations.

Cross-sectional muscle fibre areas (type I, II A and II B) were determined in duplicate biopsies from the left vastus lateralis (n = 11) and in biopsies from right and left vastus lateralis (n = 8). The SD for the difference in means between duplicate biopsies was 510 microns 2 for type I, 1020 microns 2 for type II A and 860 microns 2 for type II B. Expressed as coefficient of variation (CV) these SD constituted 10, 15 and 15%, respectively. The variation in fibre size within a sample was considerably less than the variation between samples on the assumption that at least 15-20 areas of each fibre type were measured per sample. No difference in mean fibre area for type I, II A and II B fibres was obtained between the right and left muscle. Several artefacts due to the sampling and preparing procedures are discussed and a method for determining muscle fibre areas in biopsy samples is suggested.

Adolescent↗
PubMed1984

Blood volume and hemoglobin concentration as determinants of maximal aerobic power.

Changes in blood volume (BV) and hemoglobin concentration ( [Hb] ) were induced in five healthy young men. After acute hypovolemic anemia was achieved by blood withdrawal, VO2max values decreased, while the same [Hb] due to acute plasma volume expansion (6% dextran) did not alter VO2max. After reinfusion of red blood cells, leading to hypervolemia and increased [Hb], VO2max increased. Plasma volume expansion in this situation, leading to hypervolemia at normal [Hb], resulted in a slight reduction in VO2max, which, however, remained elevated (approximately 4%) above control values. Physical performance, measured as time to exhaustion, corresponded to the changes in VO2max except for the hypervolemic anemic situation, where it decreased. Changes in peak heart rate were inversely related to BV changes, but were also influenced by [Hb]. The results point to a significant influence of the total amount of Hb rather than the blood hemoglobin concentration for obtaining a high maximal aerobic power. Thus, a reduced [Hb], concomitantly with an elevated blood volume (plasma volume), may result in an unchanged VO2max, but reduced performance time.

Adult↗
PubMed1983

Myofibrillar damage following intense eccentric exercise in man.

Muscle soreness that has a delayed onset is a common feature among both athletes and untrained individuals who engage in unusual exercises. This study was designed to provide additional morphological data to assess the relevance and significance of our previous findings that the sore muscles contain fibers with disorganized myofibrillar material. Muscle biopsies were obtained from 12 males (mean age 25 +/- 7 years), who suffered from severe soreness in their thigh muscles 18--72 h following eccentric bicycle exercise. Their strength performance were tested in parallel. Knee extensor strength was decreased at all angular velocities soon after exercise but gradually increased over the subsequent days although slower at the fastest contractions. Disturbances of the cross-striated band pattern were constantly observed. They originated from the myofibrillar Z-band, which showed marked streaming, broadening and, at places, total disruption. The disturbances were found in every second to every third fiber up to 3 days after exercise and in one tenth of the fibers 6 days following the exercise. Type 2 fibers were predominantly affected. Thus, the eccentric exercise gives rise to muscles soreness and influences, on mechanical basis and selectively with regard to fiber type, the fine structure of the contractile apparatus.

Adolescent↗
PubMed1983

Adaptive response in human skeletal muscle subjected to prolonged eccentric training.

The peripheral adaptation process associated with repeating eccentric training over a longer period of time was studied in m. vastus lateralis of eleven healthy males aged 24 +/- 4 years. The maximal dynamic concentric muscle strength was only slightly improved after 8 weeks of training. However, eccentric work capacity was dramatically increased (375%). A maximal eccentric stint immediately after fulfilled 8 weeks of training caused a selective glycogen depletion from the type 28 fibers. An increased number of type 2C fibers was observed. The ultrastructure analysis showed an essentially well-preserved fine structure. Volume density of mitochondria was somewhat higher in all fiber types after training. Z-band widths were not affected by eccentric training. It is concluded that skeletal musculature adapts itself in a functional manner to the extreme tension demands put on them. Improved coordination and reorganization of the contractile apparatus of muscle fibers are the determining mechanisms of this adaptation.

Adaptation, Physiological↗
PubMed1982

Fine structural details of human muscle fibres after fibre type specific glycogen depletion.

Type 1 and Type 2 fibres of skeletal muscle (human m. vastus lateralis), selectively depleted of glycogen by sustained submaximal muscular exercise (running 30 km), were identified at light and electron microscopical level by examination of thin and ultra-thin serial sections treated particularly for visualization of glycogen. Averaged images, obtained by lateral smearing of depleted fibres (Type 1) exhibited five clearly visible cross-bridges in the M-band and had broad Z-bands. Non-depleted fibres (Type 2) showed either three central strong and two weak outer lines in the M-band and intermediate Z-bands (Type 2A), or only three central strong lines in the M-band and narrow Z-bands (Type 2B). The depleted fibres had no subsarcolemmal accumulation of glycogen particles and practically no intermyofibrillar particles. The remaining particles were small in size and seemed almost rudimentary. In non-exercised individuals, a peculiar distribution of individual glycogen particles in the I-band and A-band was found. This distribution was accounted by the structural arrangement of the myofibrillar material.

Adult↗
PubMed1982

The needle biopsy technique for fibre type determination in human skeletal muscle--a methodological study.

The fibre type composition (type I, IIA and IIB) was determined in repeated needle biopsies from the vastus lateralis muscle of 34 healthy male subjects. Repeated biopsies were taken from one leg (n = 20), and from both legs (n = 14). The variation between duplicate biopsies was 6.2% and 12.3%, with regard to % type I-fibres, respectively. Corresponding variation in % type IIA-fibres was 4.4% and 7.3%, respectively, and in % type IIB-fibres 5.0% and 7.4%, respectively. The variation in fibre type distribution within a single biopsy was 2.2-3.0% when 200 fibres were classified and counted. Increasing the number of fibres did not reduce the calculated variation to any great extent. A major reduction of the methodological error is obtained when two biopsies are taken from the same site of the muscle. The error in the technique in classifying the type I-fibres was slight; the classification between the subgroups of type II-fibres was, however, to some extent subjected to personal estimate. There was no consistent difference in fibre type composition between the right and the left leg.

Adenosine Triphosphatases↗
PubMed1982

Acute hypervolemia, cardiac performance, and aerobic power during exercise.

The relative importance of blood volume (BV) for the maximum aerobic power (VO2 max) was evaluated in healthy subjects by sequential measurements without intervention under two conditions: 1) after hemodilution with a plasma expander, thus increasing BV but keeping red cell mass constant and lowering hemoglobin concentration [Hb], and 2) after whole blood withdrawal, which restored BV to control conditions but reduced red cell mass and [Hb] to equal conditions under 1. After BV expansion (avg 700 ml), we found an unchanged VO2 max compared with control data despite lowered [Hb]. Cardiac output (Q) was increased after BV expansion at rest and during all exercise levels (maximum 27.4 and 29.5 l . min-1, respectively). Peak stroke volume was increased from 144 to 173 ml. Arterial blood pressures were either unchanged or lowered. In contrast, after blood letting to a similar [Hb], we found a significantly reduced VO2 max. These findings indicate a significant influence of the size of the blood volume on cardiac performance. The increased Qmax is discussed in relation to preload, inotropic state, heart rate, and afterload. Plasma volume expansion causes increased preload which may explain this primary effect on the central circulation (Frank-Starling effect).

Adult↗
PubMed1981

A morphological study of delayed muscle soreness.

Biopsies, taken up to 1 week postexercise, from the soleus muscles of 5 healthy males (20--34 years old) suffering from pronounced exercise-induced delayed muscle soreness were analyzed morphologically. There was no evidence for ischemic tissue injury or mechanical fibre disruption. However, at the subcellular level frequent myofibrillar disturbances, especially with regard to the Z-bands, were noted. Thus, the contractile machinery of overloaded muscle fibres seemed to be partially distorted several days following exercise.

Adult↗
PubMed1981

Physical training in rheumatoid arthritis: a controlled long-term study. I.

Twenty-three patients with rheumatoid arthritis (RA) have been given physical training for 4 to 8 years. To compare, we have had a control group of equal size and with the same disease severity. The training program consisted of home-training and for most of the patients also group-training led by a physiotherapist. During the observation period we have found a significantly less pronounced progress of X-ray changes in the joints of the active patients compared with control patients. Physiological tests and clinical parameters, including sick-pension and sick-leave, show unanimously a better disease outcome in the active group of patients. There is probably a risk of overuse or disuse of the joints in RA but we believe that it is better to be overactive rather than the reverse. As in many other diseases, the general prescription of rest in RA is not adequate.

Adult↗
PubMed1980

Time course of adaptation to low intensity training in sedentary men: dissociation of central and local effects.

The oxygen transporting capacity and the metabolic capacity of the vastus lateralis muscle were followed in parallel in 9 sedentary, overweighted men during a low intensity training program. Measurements were made at 0, 3, 6, 9, 12 and 30 weeks. Maximal oxygen uptake increased in an approximately linear fashion during the first 12 weeks (11%), but decreased a little (3%) during the following 18 weeks. Mean body weight decreased 8% (7.4 kg) during the training. The distribution of muscle fibre types, including the subgroups of type II fibres, did not change. Muscle enzyme activities remained essentially unchanged during the training. It was concluded that "central" och "local" adaptation need not occur in parallel, and that the leg oxygen utilization capacity probably does not limit the whole body's maximal oxygen uptake.

3-Hydroxyacyl CoA Dehydrogenases↗