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Biomedical subjects

C A Carlsson

Publications and source records attributed to C A Carlsson.

At least 55 records · Page 3Linked to original sources
PubMed1980

Surgical decision analysis. Methodological aspects of statistical evaluations in therapeutic trials.

This report aims at discussing some of the sources of error and pitfalls involved in evaluating the efficiency of alternative modes of therapy in clinical materials. One of the main obstacles in such analysis is that the therapeutic groups are basically different due to the original selection of patients. In a previous paper (Pellettieri, 1980) a special method was worked out to circumvent this problem. The method requires that the variables of main prognostic importance can be identified. Patients in the different therapeutic groups who have identical patterns of combination of variables (risk profiles) can then be compared and the efficiency of different treatment programs can be evaluated. We believe that this method can be used in other fields of medicine.

Adult↗
PubMed1979

Relationships between energy fluence and energy incident on, emitted by or imparted to a body.

From knowledge of the energy and angular distribution of the fluence around a body, the energy incident on, emitted by or imparted to a body can be calculated. The calculation is easily performed if the quantity 'vectorial fluence' is used. Examples taken from the literature are used to illustrate the erroneous results obtained by integrating energy fluence over area instead of integrating the scalar product of vectorial energy fluence and vectorial area.

Energy Transfer↗
PubMed1979

Effect of dorsal column stimulation on pain-induced intracerebral impulse patterns.

Evoked electrical potentials were recorded via intracerebral electrodes in a patient with stump and phantom limb pain who had a previously implanted dorsal column stimulator. When pain was elicited by peripheral stimulation it was found that positive deflections appeared in the ventrolateral nucleus of the thalamus at time latencies corresponding to the propagation velocities of A delta- and C-fibres. Dorsal column stimulation completely eliminated the C-fibres. Dorsal column stimulation completely eliminated the C-fibre deflection and partially eliminated the A delta-fibre deflection.

Adult↗
PubMed1978

Effects of electrical intravaginal stimulation on bladder volume: an experimental and clinical study.

Clinical observations have indicated that not only stress incontinence due to defective urethral closure but also urge incontinence due to bladder hyperactivity can be successfully treated by electrical stimulation of the pelvic floor. Clinical investigations revealed that intravaginal electrical stimulation caused bladder inhibition registered as a volume increase. This inhibition was most marked at a low stimulation frequency (10 Hz). Animal experiments indicated that the bladder inhibition was achieved by autonomic spinal reflex mechanisms activated by stimulation of pudendal afferents.

Animals↗
PubMed1978

The effect of transcutaneous electrical nerve stimulation (TNS) on joint pain in patients with rheumatoid arthritis.

The effect of transcutaneous nerve stimulation (TNS) on joint pain was studied in patients with rheumatoid arthritis. Three different forms of TNS were used in an attempt to evaluate the influence of placebo effects. The results were evaluated by means of loading tests and from the patients' own assessments of pain relief. High intensity TNS near the painful joint gave pain relief of varying degree in 95% of the patients, while TNS of low intensity and TNS applied at a remote site gave an improvement in 75% and 5% respectively. It seems quite clear that TNS is effective in reducing joint pain. There are a number of factors which intimate that this improvement is not merely a placebo effect.

Adult↗
PubMed1978

[Pain relief during delivery by transcutaneous electrical nerve stimulation (author's transl)].

The analgesic effect of transcutaneous electrical nerve stimulation (TNS) during delivery has been evaluated. The usual technique of TNS was modified to suit the specific needs of pain control during the whole course of delivery. Two pairs of electrodes were taped to the patient's back, one pair level with the spinal processes Th 10-L1 and the other with S2-S4, corresponding to the influx of pain during the first and second stages respectively. Stimulation was delivered as biphasic pulses at 60-80 Hz. A low-intensity stimulation was given continuously, and a high-intensity stimulation was initiated by the patient herself whenever pain increased. As a rule, stimulation via the thoracic electrodes was given throughout delivery and sacral stimulation added from the later part of the first stage. No complications with respect to mother or child have occured. Three hundred and forty-seven women have been treated, 47% of them considered the analgesia with TNS to be good or very good, 42% experienced a certain effect whil 11% considered that TNS made no difference. In view of the relatively good results and the absence of complications, the authors recommend the method as a primary pain relieving measure to which conventional methods can be added if necessary.

Afferent Pathways↗
PubMed1977

Glial cell characteristics in bulk-prepared cell fractions from human brain tumours.

The heterogeneity of brain tumours, especially in the glioblastoma group, makes biochemical characterization of pieces of the tumours hazardous even with extensive histological controls. This study employs a technique by which separate cell populations are subsequently isolated from the tumours by means of density gradient centrifugation. Cells isolated from glial brain tumours with low density sedimentation rates show the highest levels of glial cell characteristics, i.e. S-100 content and active uptake of the neurotransmitter GABA.

Astrocytoma↗
PubMed1977

The effect of intravaginal electrical stimulation on the feline urethra and urinary bladder. Electrical parameters.

Intravaginal electrical stimulation (IVS) in cats caused urethral closure and bladder inhibition. The aim was to ascertain the electrical parameters most appropriate for these effects. Minimum voltage was used as main criterion to select an effective, non-destructive stimulation when the shape, frequency and duration of the pulses were systematically varied. Urethral closure was achieved at minimum voltage (3 V) with alternating pulses at a frequency of 50 Hz and a pulse duration of 1.5 ms. Corresponding optimal parameters for bladder inhibition were: alternating pulses, 10 Hz and 1.5 ms. Minimum voltage was 1 V. Moreover, the positions of the electrodes were of significance for the responses. The clinical implications of these findings are that: 1)more differentiated treatment of incontinence could be achieved by adapting the stimulation parameters to the cause of incontinence, and 2) specific electrode positions would probably give optimal responses.

Animals↗
PubMed1977

Mechanisms for closure of the human urethra during intravaginal electrical stimulation.

The effect of intravaginal electrical stimulation (IVS) on the urethral pressure profile (UPP) before and during succinylcholine blockade or spinal anaesthesia was studied in patients with stress incontinence and in patients with clinically normal urethral function. During succinylcholine blockade, the UPP was lowered to 74% and during spinal anaesthesia to 39% of the original maximal UPP. IVS could not influence the UPP during succinylcholine blockade, while the UPP could be restored during spinal anaesthesia when the stimulation strength was increased 3 to 4 times. The following conclusions were arrived at: 1) The urethral effect of IVS is due to activation of somatic nerves and not to activation of nerves supplying smooth muscles or direct activation of striated and smooth muscles. 2) The more pronounced depression of the UPP during spinal anaesthesia compared to succinylcholine blockade should be caused by the loss of nervous activity of the smooth muscles. 3) The fact that the UPP could be restored during spinal anaesthesia indicates that activation of somatic efferents can compensate for the loss of striated and smooth muscle activity. Therefore, IVS can control incontinence in partial lower motor neuron lesions, provided a sufficient number of efferent neurons are preserved.

Adult↗
PubMed1976

Attenuation equalizing filter in diagnostic radiography. Advantages calculated by a Monte Carlo technique.

The value of an attenuation equalizing filter (equalizer) has been examined by calculation using a Monte Carlo technique. The contrast enhancement caused by the equalizer is the net result of three factors: (1) The first factor arises from the contrast change caused by the difference in detector characteristics at the different energies absorbed in the detector with and without equalizer. (2) The second factor is due to the contrast change caused by the different ratios of primary to total radiation reaching the detector. (3) Finally, the third factor describes how the transparency of the object is changed by the different primary filtration with equalizer. An example is given of the reduction in radiation energy absorbed by the patient and the question of how far the attenuation equalization can be driven is discussed.

Computers↗