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Biomedical subjects

J Karlsson

Publications and source records attributed to J Karlsson.

At least 217 records · Page 12Linked to original sources
PubMed1986

Lowering of the patella secondary to anterior advancement of the tibial tubercle for the patellofemoral pain syndrome.

From a series of 72 patients treated with anterior advancement of the tibial tubercle for patellofemoral pain syndrome, secondary lowering of the patella was noted in eight. In all eight patients the results were poor following surgery, with severe disabling retro- and peripatellar pain and atrophy of the quadriceps muscle. We describe this complication and illustrate and discuss the biomechanical consequences. The shortening of the patellar ligament and lever arm of the ligament were determined from radiographs of the knee joints before and after surgery. A theoretical analysis was made of the compressive force in the patellofemoral joint in one of these patients. The Insall-Salvati index decreased from 0.88-1.25 (mean 1.07) preoperatively to 0.54-0.78 (mean 0.70) at follow-up, 1.0-2.5 years post-operatively. The lowering of the patella was correlated to a reduction of the lever arm of the patellar ligament in seven patients. The mechanism behind the lowering of the patella is obscure, but the reduced lever arm of the patellar ligament will increase the compressive force in the patellofemoral joint, and this might be one explanation of the poor results. Impaired congruity of the patellofemoral joint, increased tension in the patellar ligament, and increased pressure against the quadriceps tendon are other possible explanations.

Adult↗
PubMed1986

Survey of anthelmintic resistance in Western Australian sheep flocks. 1. Prevalence.

Between July 1981 and December 1983, 116 randomly selected sheep farms in the south west of Western Australian were surveyed for resistance to anthelmintics. A faecal worm egg count reduction test was carried out on each farm. Anthelmintics tested were thiabendazole (44 mg/kg) and levamisole (7.5 mg/kg) given by intra-ruminal injection and comparisons were made with an untreated group on each farm. Successful tests were carried out on 84 farms and 68% of these had resistant worms present. The prevalence of thiabendazole resistant populations was for H. contortus 18%; Teladorsagia, 41% and Trichostrongylus, 48% and for levamisole resistant populations H. contortus, 10%; Teladorsagia, 41%; Trichostrongylus, 24%, and Nematodirus, 10%. Multiple resistant populations were found on 17% of farms. Although the distribution of nematode genera varied between the 400 to 750 mm and the greater than 750 mm rainfall zones there was no significant difference in the prevalence of resistance between zones. About one third of resistant populations were severely resistant (less than 60% reduction). It is likely that resistant worms were present on many farms without causing clinical disease and continued anthelmintic selection pressure will result in further development of resistance.

Animals↗
PubMed1986

Survey of anthelmintic resistance in Western Australian sheep flocks. 2. Relationship with sheep management and parasite control practices.

Owners of 116 farms, whose flocks had been tested for anthelmintic resistance, were interviewed to determine their use of various sheep management and parasite control practices and their knowledge and adoption of recommended procedures for the prevention and control of resistance. Farmers knowledge of current recommendations related mainly to changing drenches and drench groups. Other aspects of the recommended program including reduction of drenching frequency and the use of alternative management strategies were not considered as important by farmers. For most questions a high proportion of farmers (greater than 20%) had no opinion. Associations between various strategies for nematode control and resistance of Trichostrongylus and Teladorsagia to thiabendazole and levamisole were examined. These relationships differed between anthelmintics and nematode genera. A number of factors were related to resistance of one or both nematode genera to one or both anthelmintic groups. These factors included flock size, percentage of ewes in the flock, cattle number, main sheep production activity, grazing strategy, frequency of drenching, changes in the frequency of drenching, number of summer drenches and the method of estimating dose rates. It was concluded that the methods employed to control anthelmintic resistance may vary with the nematode, its resistance status and the anthelmintic to which it is exposed. Modifications to the previously recommended program have been proposed which incorporate selection of the anthelmintic to be used following a test for anthelmintic resistance.

Animal Husbandry↗
PubMed1985

Metabolic adaptations to exercise: a review of potential beta-adrenoceptor antagonist effects.

Human skeletal muscle contains 2 muscle fiber types: slow twitch (type I) and fast twitch (type II). They have different profiles including their biochemical, metabolic, O2 diffusion, microcirculatory and neuromotor characteristics. The slow twitch fiber represents endurance, high combustive potential and recruitment during moderate activity; in contrast, the fast twitch represents explosiveness, force, high capacity for phosphate splitting and lactate formation, but is more fatiguable. A muscle rich in slow twitch fibers is confined to low peripheral resistance at rest and during exercise, higher exercise leg blood flow and higher maximal oxygen uptake (VO2 max). During graded exercise lactate has been shown to be a good marker for the metabolic and circulatory characteristics of the contracting muscle and the exercise intensity (W) eliciting a blood lactate concentration of 4 mmol/liter-1 [(WOBLA) from onset of blood lactate accumulation] integrated for peripheral metabolic, neuromotor and central circulatory potentials both in health and disease. It is well known that a blood lactate level greater than 4 mmol/liter-1 represents a major increase in sympathetic tone and is incompatible with endurance or prolonged exercise. With prolonged exercise and sympathetic regulation both circulation and metabolism adapt. Adipose tissue is stimulated and fatty acids are released. Muscle tissue lipoprotein lipase activity is enhanced; that is, there is increased utilization of blood triglycerides for local lipolysis in the capillary bed of the contracting muscle. Both mechanisms will increase fatty acid availability and induce a "glycogen-sparing effect" resulting in a reduced respiratory exchange ratio. Studies have shown that both the magnitude of the initial glycogen stores and these adaptive responses will determine performance time. With age, changes take place in heart rate regulation, neuromotor control and muscle fibers. Thus VO2 max is decreased, but partly compensated for by a fast motor unit and fiber loss leading to a muscle more rich in slow twitch fibers--an "endurance training-like effect." Relative endurance is also increased with age; however, lactate metabolism is still a critical feature. The OBLA concept describes capacity for both occupational and leisure-time physical activity.

Adenosine Triphosphate↗
PubMed1985

Anterior advancement of the tibial tuberosity in the treatment of the patellofemoral pain syndrome.

Seventy-two patients with disabling patellofemoral pain were treated with anterior advancement of the tibial tuberosity. In a follow-up examination 1-5 years (mean 2.5) postoperatively, 57% of the patients had improved, 19% were unchanged, and 24% were worse. The high failure rate is disturbing, and we warn against too frequent use of the anterior tuberosity advancement procedure. Patients with patellofemoral pain should be approached by establishing a specific diagnosis and applying a specific treatment. In this study we concluded that the only patients who might benefit from the operation were those with grade I-II changes of the patellar cartilage.

Adolescent↗
PubMed1985

Effects of age on the mother-child interactions of ADD-H and normal boys.

The interactions of 60 ADD-H boys with their mothers were compared to those of 60 normal boys during both free-play and task situations. Both groups were equally subdivided into five age levels (years 5, 6, 7, 8, and 9). In free play, ADD-H boys played more independently of and were more negative toward their mothers, while their mothers gave more commands and initiated fewer interactions than normal mother-child dyads. There were no effects of age in this setting. During the task setting, ADD-H boys were less compliant, sustained their compliance for shorter time periods, and were more negative and off task than the normal boys. Mothers of ADD-H boys gave more commands, were more negative, initiated fewer interactions, and responded with greater control over both compliance and off-task behavior than did normal mothers. Several age effects were noted suggesting that older boys in both groups were more compliant while their mothers gave fewer commands and controlled their compliance less than the mother-child dyads of younger boys. While the interactions of ADD-H boys appear to improve with age, the boys continue to display a developmental lag in social behavior that is more evident with increasing situational demands.

Age Factors↗
PubMed1985

Blood pressure response in relation to blood lactate during exercise in patients with essential hypertension.

Thirty-four untreated patients with essential hypertension WHO I-II, 17 patients under treatment with beta-blockade, and 32 healthy controls with a wide range of exercise capacity were studied at loadless pedaling (W0) and at the work load eliciting a blood lactate concentration corresponding to 4 mmol X l-1 (onset of blood lactate accumulation or OBLA). At W0 the treated patients had approximately the same systolic blood pressure (SBP) as the healthy controls, while the untreated patients had a higher SBP than the controls. At WOBLA the SBP was higher in the untreated patients than in both the treated patients and the healthy controls. On an individual basis it was found in the healthy controls and the untreated patients that the SBP at WOBLA showed a slight and insignificant increase versus SBP at W0, whereas the difference in SBP between WOBLA and W0 ("exercise SBP increase") demonstrated an inverse relationship (P less than 0.001-0,01) versus W0. It was suggested that for both healthy controls and untreated patients the exercise SBP depended on a "basal" level as depicted by W0 and a further SBP increase due to the exercise load. The difference between the two groups was that the patients with untreated hypertension displayed their relationships at higher pressure levels indicating the presence of a hyperkinetic drive. The treated patients appeared to have a lower increase in SBP between W0 and WOBLA than any other group, suggesting an unfavorable effect of the beta-blockade.

Adrenergic beta-Antagonists↗
PubMed1985

Developmental changes in the mother-child interactions of hyperactive boys: effects of two dose levels of Ritalin.

The mother-child interactions of 60 hyperactive children subdivided equally into five age levels (years 5, 6, 7, 8 and 9) were studied during free play and task periods in a double-blind drug-placebo evaluation of two dose levels of Ritalin (0.3 and 0.7 mg/kg bid.) on these interactions. No effects for age or drug condition were found during free play. In contrast, age effects were significant in the task period with the children increasing their compliance and sustained attention with age. In response, mothers decreased their direction and control while increasing their passive observation of the children. Several drug effects were found during the task period, indicating that only the high dose of Ritalin produced improvements in child compliance. However, both doses resulted in decreases in mothers' controlling reactions to the child's compliance and off-task behavior as well as in ratings of home behavior problems. Drug effects were essentially the same across all five age levels. The interaction patterns of hyperactive children are similar to those found in younger normal children in previous research, apparently reflecting a chronic lag in this pattern in hyperactive children that may be improved with stimulant medication.

Adult↗
PubMed1985

Skeletal muscle glycolysis during submaximal exercise following acute beta-adrenergic blockade in man.

The present study describes the influence of beta-adrenergic blockade on glycogen utilization and lactate accumulation in skeletal muscle of exercising man. Twelve physically active men were examined during 25 min of continuous cycle exercise equivalent to 65% of their maximal oxygen uptake both with and without oral administration of 80 mg of propranolol (Inderal). Heart rate, oxygen uptake, rate of perceived exertion (RPE) and blood lactate concentration were measured during exercise. Muscle biopsies were obtained from m. vastus lateralis after 5 and 25 min of exercise. Beta-adrenergic blockade decreased steady state exercise heart rate by (mean +/- SD) 35 +/- 10 beats . min-1 (P less than 0.001) and oxygen uptake from 2.47 to 2.39 l . min-1 (P less than 0.01). Muscle glycogen decreased from the 5th to the 25th min of exercise, and beta-blockade had no significant effect on this decrease. In contrast to without drug, beta-blockade resulted in a decrease (P less than 0.05) in muscle lactate concentration from the 5th (6.9 mmol . kg-1 w./w.) to the 25th min (4.8 mmol . kg-1 w./w.). Similarly blood lactate levels were lower (P less than 0.05) with than without beta-blockade in the last but not the first 10 min of exercise. The alteration in muscle lactate concentration pattern following beta-blockade, may imply that adrenergic effects per se contribute to the stimulation of glycolysis during submaximal exercise, except in its earliest phase. Nevertheless, the effect is not great enough to produce substantial differences in glycogen utilization.

Adult↗
PubMed1985

Muscle fiber types and size in trained and untrained muscles of elite athletes.

Tissue samples were obtained from vastus lateralis and deltoid muscles of physical education students (n = 12), Greco-Roman wrestlers (n = 8), flat-water kayakers (n = 9), middle- and long-distance runners (n = 9), and olympic weight and power lifters (n = 7). Histochemical stainings for myofibrillar adenosinetriphosphatase and NADH-tetrazolium reductase were applied to assess the relative distribution of fast-twitch and slow-twitch (ST) muscle fiber types and fiber size. The %ST was not different in the vastus (mean SD 48 +/- 14) and deltoid (56 +/- 13) muscles. The %ST was higher (P less than 0.001), however, in the deltoid compared with vastus muscle of kayakers. This pattern was reversed in runners (P less than 0.001). The %ST of the vastus was higher (P less than 0.001) in runners than in any of the other groups. The %ST of the deltoid muscle was higher in kayakers than in students, runners (P less than 0.001), and lifters (P less than 0.05). The mean fiber area and the area of ST fibers were greater (P less than 0.01) in the vastus than the deltoid muscle. Our data show a difference in fiber type distribution between the trained and nontrained muscles of endurance athletes. This pattern may reflect the adaptive response to long-term endurance training.

Adult↗
PubMed1984

Fractures of the scaphoid bone. A follow-up study.

Fracture of the scaphoid bone is the most common fracture of the carpal bones (Dunn 1972). Primary diagnosis can be difficult, and misdiagnosis with subsequent inadequate treatment often results in a permanently painful wrist with reduced function of the hand. We have observed that the immobilization time for scaphoid fractures at this clinic is shorter than is usually reported (Cooney et al. 1980; Dunn 1972; Eddeland et al. 1975). We have also observed that in some cases major diastasis in the fractures coincided with delayed union or non-union. Since opinions on the treatment of these fractures have varied on some points, we find it worthwhile to present our results. The major aims of the study were to evaluate whether the short immobilization time has any bearing on the fracture healing and, furthermore, whether the presence of a significant diastasis of the fracture affects the healing.

Adolescent↗
PubMed1984

Muscle metabolite accumulation following maximal exercise. A comparison between short-term and prolonged kayak performance.

Five elite flatwater kayak paddlers were studied during indoor simulated 500 and 10,000-m races, with performance times of 2 and 45 min, respectively. Muscle biopsies were obtained from the midportion of m. deltoideus immediately pre and post exercise. Concentrations of adenosine triphosphate (ATP), creatine phosphate (CP), glucose, glucose-6-phosphate (G-6-P), glycogen, and lactate were subsequently determined. Short term exercise resulted in statistically significant increases in glucose (P less than 0.001), G-6-P (P less than 0.05) and lactate (P less than 0.01) concentration concomitant with decreased CP (P less than 0.05) and glycogen (P less than 0.01). Following prolonged exercise, a non-significant elevation in glucose and a reduction (P less than 0.01) in glycogen were demonstrated. Evidently the metabolic demands for kayak competitions at 500 and 10,000 m are different. Thus, the energy contribution from glycolytic precursors and the anaerobic component is of greater relative importance in short distances than in exercise of long duration. A generalization of the findings to other athletic events of varying distances is proposed. The present data on arm-exercise is consistent with previous findings obtained in connection with leg exercises.

Adenosine Triphosphate↗
PubMed1984

Dislocation of the elbow joint.

Although dislocation of the elbow is a common injury, it has been the subject of very few papers in the orthopaedic literature during the last 20 years. The recommendations for treatment have usually been conservative but in later years wider indications for surgical treatment with ligament repair have been recommended. Seventy-two patients with simple elbow dislocations (38) and fracture dislocations (34) treated at the departments of orthopaedic surgery in Göteborg 1975-1980 were reviewed. Results for patients with simple dislocations were excellent and good in 85 per cent and no difference could be recorded between those treated by surgery and those treated conservatively. Results after treatment of fracture-dislocations were generally worse and only 41 per cent achieved excellent or good results. We concluded that most simple dislocations should be treated conservatively with closed reduction followed by a short period of immobilization. In fracture-dislocations surgical repair of the elbow ligaments should be considered especially when the radial head has been excised.

Adult↗
PubMed1984

Effects of exhaustive, isometric training on lactate accumulation in different muscle fiber types.

Four physically active men took part in a 6-week training program. They performed three sustained leg press contractions at 50% maximal isometric strength (MIS) to exhaustion 3-4 times a week. Before training and following performance of 50% MIS to exhaustion, muscle biopsies were obtained from m. vastus lateralis for subsequent lactate analysis on freeze-dried fiber fragments. Post-training biopsies were taken (a) after a contraction performed at the same tension level and for the same time period and (b) after an exhaustive contraction held at 50% of the post-training MIS. Prior to training, lactate concentration in fast-twitch (FT) and slow-twitch (ST) muscle fibers averaged 29.8 (range 27.9-31.4) and 28.7 (24.0-32.4) mmol X kg-1 w.w, respectively. After training the values were 16.7 (11.0-27.5) (FT) and 14.1 (6.1-26.9) (ST). Lactate concentrations following exhaustive contraction were 21.3 (16.3-27.9) (FT) and 17.8 (11.5-28.0) (ST). Thus, for all situations studied, lactate concentration was greatest in FT fibers, and this difference tended to increase with training, irrespective of whether or not the contraction was maintained until the onset of exhaustion.

Adult↗
PubMed1984

Histochemical and metabolic changes in lower leg muscles in exercise-induced pain.

Intramuscular pressure, fiber type distribution, relative cross-sectional area of slow-twitch muscle fibers, muscle lactate, and water content were studied in eight patients with medial tibial syndrome and in eight patients with chronic anterior compartment syndrome. The variables were determined before and after standardized exercise that provoked lower leg pain. In patients with medial tibial syndrome, the intramuscular pressures in the deep posterior compartment were not elevated before or 10 min after exercise. In patients with chronic anterior compartment syndrome, there was a significant post-exercise increase from 9 +/- 9 to 48 +/- 35 mmHg (P less than 0.01) in the anterior tibial compartment. The patients with medial tibial syndrome and chronic anterior compartment syndrome had a predominance of slow-twitch fibers in the deep posterior (69% and 77%, respectively) as well as in the anterior tibial (69% and 80%, respectively) compartments. The slow-twitch muscle fibers covered less cross-sectional area than could be expected from the fiber composition. Muscle lactate concentration did not increase after exercise in any of the patient groups in contrast to the healthy controls in whom there was an increase (P less than 0.05). The lactate change ratio (post-exercise/pre-exercise) correlated negatively to the percentage of slow-twitch muscle fibers (P less than 0.05) in the patients but not in the healthy controls. Muscle water content increased for both patient groups in the anterior tibial but not in the deep posterior compartment. The findings indicate that the chronic anterior compartment syndrome is related to changes on the muscle fiber level and to a subsequently changed anaerobic metabolism and fluid infiltration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗