Biomedical subjects
Publications and source records attributed to G Eklund.
An instrument has been designed for the preparation and placement of subcutaneous implants in small laboratory animals. The usefulness and applications of the instrument have been assessed, based on experiences from 260 implants inserted subcutaneously on guinea pigs with the aid of the described instrument.
The prognostic values of clinical staging IB--III and a histopathologic malignancy grading system have been compared in a retrospective study on 338 women with invasive squamous cell carcinoma of the uterine cervix. The superiority of the grading system to staging was significant (p less than 0.01). However, staging had an additional prognostic value. Using both the malignancy grading system and clinical staging together provided a better capacity to predict the clinical outcome in individual patients. Prognostication according to clinical staging alone will result in a considerable loss of information.
The clinical and histological factors affecting prognosis for 70 patients with neuroblastomas were tested with regression analysis. Generalized tumor disease was found to be of primary importance. Significant predictors for prognosis in patients without distant metastases were operation, with or without other therapy, age less than one year and histology. When all recorded factors were analyzed the explanation value only reached 0.42. This indicates that the variation in prognosis depends upon other factors as well.
The purpose of the present work is to examine the causes of the Piper rhythm, i.e. the tendency towards rhytmical 40-60 Hz grouping of motor unit potentials in steadily contracting human muscles. At weak or moderate contraction strength individual motor units exhibited preferred firing rates which were subharmonically related to the Piper rhythm in the gross EMG. Microelectrode muscle nerve recordings provided no support for the hypothesis that the Piper rhythm is dependent on resonance-induced rhythmical volleys of afferent spindle impulses causing reflex entrainment of motor impulses. This hypothesis also seems inconsistent with the findings that Piper rhythms of similar frequency appear in muscles with widely different mechanical properties and that the rhythms are about equally prominent in muscles with brisk as in muscles with weak or absent stretch reflexes. The results suggest that the Piper rhythm is dependent on some kind of pace-maker in the spinal cord or the cerebrum which tends to entrain and synchronize motor impulses.
The methods of preoperative orthopedics: a "T-traction" procedure for unilateral clefts and a combined premaxillary pressure and expansion procedure for bilateral clefts and of early alveolar bone grafting: the Nordin's "four-flap" technique, are described in detail. The subsequent effects of treatment according to those methods were studied with roentgencephalometric analysis in cleft patients from 7 to 13 years of age. They were divided into two unilateral and one bilateral complete cleft group, all having been early bone grafted. The unilateral groups were composed of one group of 39 children operated on during the period 1960-65 without preoperative "T-traction", and another group, of 46 children, operated on in 1965-72 after preoperative "T-traction". The bilateral group included 19 children operated on 1960-72 after preoperative orthopedics. The same degree of inhibited development of the facial skeleton as found in another Swedish early bone grafted cleft group was not present in our patients. The development of the skeletal profile in our bone grafted cases, especially those in the "T-traction" group, was well within the limits of non-grafted U.S. cases, but differed from non-clefts.
The subsequent effect of preoperative maxillofacial orthopedics and early bone grafting on the development of the soft tissue profile of the face was studied with roentgencephalometric analysis on cleft patients between 7 and 13 years of age. They were divided into two unilateral and one bilateral complete-cleft group, all having been bone grafted early with the "four-flap" technique. The two unilateral groups were one group of 39 children operated on between 1960 and 1965 without preoperative orthopedics and one group of 46 children operated on between 1965 and 1972 after preoperative orthopedics ("T-traction"). The bilateral group comprised 19 children operated on between 1960 and 1972 after premaxillary retropositioning pressure, combined when necessary, with outward rotation of the lateral maxillary segments. Comparisons of facial growth were made with U.S. non-grafted clefts and with nonclefts. The effect of the preoperative orthopedic management facilitated the subsequent surgical procedure by a narrowing of the cleft and replacement of the deviated maxillary and nasal structures. The results were within limits of the non-grafted cases, with the exception of the soft tissue overlying the subnasal region. The reduced prominence of that region was explained by the primary surgical procedure, which made the lip adherent to the alveolar crest. In comparison with nonclefts, all parameters indicated a reduced growth capacity.
Explore the source record for details and available documents.
Late side effects of chemotherapy were studied in 51 women who had received at least 300 mg of melphalan for ovarian cancer and had survived for at least three years. Hematologic, statistical, and cytogenetic methods were employed. Six cases of iatrogenic leukemia were found. They appeared to represent a hematologic entity that is fairly difficult to recognize. The risk of iatrogenic leukemia in women who survived for three years or more after melphalan treatment was calculated to be 950 times greater than the leukemia risk in the total female population. The cytogenetic changes were studied with three methods focused on sister chromatid exchange, chromosome aberrations, and DNA damage. The sister chromatid exchange frequency showed a marked increase, but it was corrected within a few months. Chromosome aberrations expressed by chromosome rearrangements were increased in the peripheral lymphocytes and may persist for several years. The frequency of DNA stand breaks was decreased indicating the presence of DNA cross-links. Any of these types of genetic alteration could be the initiating event in carcinogenesis.
1. Brisk joint displacements and tendon taps were applied to voluntarily contracting wrist flexor muscles in subjects who did not attempt to react to them. Different types of mechanotransducers, some of them attached to an intramuscular needle, were used to detect mechanical oscillations in the wrist flexors, resulting from the imposed impacts. The transducer responses to the perturbations were compared with simultaneously recorded reflex electromyogram (e.m.g.) responses. Experiments were also carried out on a rubber band model, exposed to similar mechanical stimuli.2. During brisk ramp wrist extensions the transducers signalled damped muscular oscillations at 30-50 Hz. The oscillations grew in amplitude with increasing speed of onset of the stretch movement and at angular accelerations exceeding about 2 x 10(4) deg/sec(2) the e.m.g. response changed from a non-segmented to a progressively more pronounced segmented pattern. Peak intervals in the segmented reflex e.m.g. responses were similar to those of the mechanical oscillations and did not change significantly with small or moderate variations in background contraction force. Latencies from successive deflexions in the accelerometer records to corresponding deflexions in the e.m.g. were 20-25 msec.3. Damped muscular oscillations in the 30-50 Hz range were also initiated by sudden halts of voluntary wrist movements, by electrically induced twitches, and by voluntary brisk contractions. In these instances too, the mechanical oscillations were reflected in the shape of the succeeding e.m.g. response.4. The interval between the two initial peaks in the accelerometer records was always shorter with tendon taps than in ramp stretch experiments. A corresponding difference was noted in the intervals between the following two peaks in the reflex e.m.g. response.5. The initial peak in the accelerometer records could be ascribed to a wave propagated at about 40 m/sec in the wrist flexor muscles. Inconclusive results were obtained in attempts to determine whether the subsequent oscillations represented reflexions of the propagated wave at the ends of the muscle.6. The muscles were also exposed to recurrent stretch stimuli (torque pulses) with a repetition rate varying between 15 and 100 Hz. At 30-50 Hz the intramuscular oscillations reached their maximal amplitude, and such repetition rates were also most efficient in producing synchronized e.m.g. bursts, time-locked to the oscillations. The mechanical responses of the wrist flexors to single or recurrent perturbations were to a large extent mimicked by a rubber band model with a longitudinal resonance frequency of about 40 Hz.7. It is concluded that segmentation of reflex e.m.g. responses to sudden joint displacements and other types of brisk muscle perturbations to a large extent depends on the inherent resonance characteristics of musculo-tendinous structures. Primary spindle endings with their high vibration sensitivity and their segmental projections to alpha-motoneurones are believed to be the receptors primarily responsible for reflex entrainment of the motor impulses.
1. Experiments were performed to check the validity of previous claims concerning the ;long-loop' aetiology of ;late' reflex electromyogram (e.m.g.) responses to muscle stretch in man. The primary aim was to investigate whether observations previously presented in favour of the ;long-loop hypothesis' are explicable also in terms of the ;resonance hypothesis', according to which the ;late' reflex components represent spinal, short-latency responses to intramuscular oscillations initiated by the impact.2. The contracting wrist flexors of healthy subjects were exposed to trains of recurrent 25-50 Hz stretch stimuli (wrist torque pulses). Each of the initial two or three pulses in the train was followed by e.m.g. peaks with a latency of 20-25 msec. The e.m.g. peaks driven in this way had the following characteristics in common with the successive two or three e.m.g. peaks which were induced by single ramp stretches or tendon taps. (a) Changes in stimulus parameters which altered the strength of the initial e.m.g. peak often had an opposite effect on the strength of the succeeding peak(s). Muscle vibration which attenuated the initial peak often enchanced the succeeding one(s). (b) The initial e.m.g. peak was less affected than the succeeding peak(s) by the subjects' attempts to respond with rapid ;resist' or ;let go' reactions.3. Intramuscular oscillations (monitored by a needle accelerometer) and e.m.g. responses evoked by single ramp stretches and/or tendon taps were also studied in the long thumb flexor, the calf muscles and the masseter muscle. In the thumb flexor, the initial accelerometer deflexion was only rarely succeeded by a short latency e.m.g. peak, but the succeeding wave in the needle accelerogram was followed by such a peak, appearing about 40 msec after stimulus application. By contrast, the calf muscles and the jaw elevators exhibited a high amplitude, short-latency e.m.g. response to the first but only rarely to the second intramuscular oscillation wave.4. The interval between initial and second e.m.g. peaks following tendon taps was longer for calf muscles than for wrist flexors and longer for wrist flexors than for jaw elevators. Similar differences were observed with respect to the intervals between the damped intramuscular oscillations initiated by the impacts.5. Without denying the existence of ;long-loop reflexes' it is concluded that the characteristics of the ;late' reflex responses to muscle stretch in man are explicable also in terms of the ;resonance hypothesis'.
Isokinetic torque of the knee and elbow during maximal extension and flexion and isometric strength of the handgrip, as well as balance and some circulatory variables, were tested in 37 patients one year after an acute stroke. Correlations with locomotion, household work and other activities of daily living (ADL) were tested. Male patients who had received special activation on the ward for up to 4 weeks after the stroke showed a significantly smaller difference in strength between the paretic and non-paretic knee at an angular velocity of 90 degrees per second than males who had received only routine activation on their ward. There was a high correlation between locomotion and the isokinetic torque of the paretic knee and also between locomotion and balance. The correlations between elbow strength and ADL functions were weaker. It was concluded that the evaluation of the isokinetic muscle torque of the knee and the balance tests are valid instruments for estimating functional capacity after a stroke.
The detection of 4 cases of leukaemia among telephone operators at the Telecommunications Administration in Gothenburg within a period of 6 years (1969-74) evoked disquiet among the employees. Following an inquiry to the National Board of Health and Welfare a retrospective study was undertaken with a view to examining whether this incidence was consistent with the risk for the country as a whole. The study was based on the newly established Cancer-Environment Registry for the period 1961-73 covering the entire country. This was the first occasion on which the Registry had been applied in an investigation of cancer risk for a specific occupational group. The analysis disclosed no higher risk of leukaemia among telephone operators in the Telecommunications Administration in Sweden than among the population as a whole.
The predictive value of a malignancy grading system embodied by 8 histopathologic parameters and of staging, age, year of admission and the different treatment modalities were compared in relation to 5- and 8-year survival. The material consisted of 196 patients in stage II according to the FIGO classification. The grading system proved superior with high significance (p less than 0.001) to the other predictors including each histopathologic parameter apart from vascular invasion (p = 0.01). All histopathologic parameters but 2 (differentiation into cell type and mitosis) exhibited significant (p less than 0.01) decrease in survival with higher grade at the 5- and 8-year controls. Patients in stage II could be divided into groups with low, intermediate and high malignancy points. Both groups of extremes showed a marked and highly significant difference in survival rates compared with the intermediate group, and the grading system made it possible to predict 60 per cent of the patients with acceptable specificity. In the group of high malignant tumours the system maintained a continual prognostic value even among patients still alive at the 5-year control.
A new histopathologic malignancy index has previously proved capable of permitting discrimination of patients with carcinoma of the uterine cervix (stage II) with respect to prognosis. Eight histopathologic items graded from 1 to 3 add up to constitute the malignancy index. By regression analysis the number of items could be reduced to 4. Seemingly without loss in the prediction value a partial index was elaborated by the following 4 items: mitosis, mode of invasion, cellular response, and vascular invasion, the latter attributed double the weight. The predictive value of the partial index seemed to be as good as that of the previous malignancy index on an independent materials as well.
Explore the source record for details and available documents.
The introduction of low-oestrogen oral contraceptives in Sweden and the concomitant disappearance of high-dose preparations did not result in a lowering of the mortality of fertile women from thromboembolic disease. Morbidity due to thromboembolism seems to have fallen, and the number of thromboembolic incidents reported to the Swedish Adverse Drug Reaction Committee decreased dramatically. The decrease was due exclusively to a reduction in venous thromboembolic disease: the frequency of arterial complications (cerebral and coronary) remained constant.
Serum was analyzed for zinc in 51 patients of varying age and with varying degrees of alveolar bone loss as recorded on roentgenograms. There was a reversed correlation between marginal alveolar bone loss and serum zinc levels. The observations are discussed in relation to the physiological functions of zinc.
Prognostic factors and the blood chemistry were analyzed prior to treatment in 33 consecutive patients with primary osteosarcoma. The only variables of blood chemistry with values outside the normal range were alkaline phosphatase and ESR, which were increased. There was a correlation between certain prognostic factors and between some of these and a number of the blood variables. The degree of malignancy tended to be lower in the female than in the male patients. Distally located tumors tended to be smaller and were assessed with a less marked effect on the blood variables than those located proximally.