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Biomedical subjects

J Carlsson

Publications and source records attributed to J Carlsson.

At least 73 records · Page 4Linked to original sources
PubMed2000

Homogeneity and diameter of linear lesions induced with multipolar ablation catheters: in vitro and in vivo comparison of pulsed versus continuous radiofrequency energy delivery.

BACKGROUND: For invasive treatment of atrial fibrillation, linear lesions induced with multipolar ablation catheters (MAC) are needed to prevent recurrence. The aim of the study was to compare the efficacy of pulsed versus continuous radiofrequency (RF)-energy delivery using MAC. METHODS: In vitro tests were performed using endomyocardial preparations of fresh pig hearts in a 10-liter-bath of physiologic saline solution (37 degrees C) at constant flow conditions (1.5 l/min). The MAC were placed with a constant pressure of 20 ponds onto the endocardium. The energy (generator: Osypka HAT 200 S) was delivered either pulsed (4 electrodes simultaneously, 5ms duty-cycle) or continuously (each electrode separately). In vivo experiments were performed in 6 anesthetized pigs using fluoroscopic positioning of MAC at 40 different intracardial positions and with similar conditions as in vitro experiments. Lesion volume (LV) was calculated after measuring lesion diameter with a microcaliper. The homogeneity of the lesions (LH) was classified from 1-4; with 1 as highest homogeneity. RESULTS: Pulsed energy delivery produced more homogeneous linear lesions in significantly less time. There was no difference in electrode temperature values (50.2 +/- 0.8 and 51.3 +/- 1.4 degrees C) in vitro and in vivo. In the in vivo experiments, lesion depth and calculated lesion volume were less in both modes of energy delivery but pulsed energy delivery was superior regarding lesion depth and homogeneity. CONCLUSION: With pulsed energy delivery it is possible to create linear lesions of significantly greater homogeneity. Moreover, larger lesions are induced in less time by pulsed energy delivery in vitro and in vivo.

Animals↗
PubMed2000

Introduction of thiol-reactive structures on to soluble and insoluble proteins.

When proteins containing disulphide groups were oxidized with magnesium monoperoxyphthalate at acidic pH, they acquired the property of binding thiol compounds. This was the case with the insoluble protein keratin, chosen for having a large number of disulphide bridges, and with soluble ones like BSA and immunoglobulins. The potential applications of some of these modified proteins for the preparation of soluble bioconjugates have been explored. As a particular example of an application, the immobilization of activated IgG on to solid phases might provide a new way for preparing immunoadsorbents.

Amino Acids↗
PubMed2000

Stroke prevention practices in patients with atrial fibrillation and pacemaker therapy: evidence for under-use of anticoagulation.

This study presents a survey of pacemaker patients followed in a pacemaker clinic. Three hundred and twenty-six patients of mean age 77.7 +/- 9.6 years, 52% female, 75% VVI, 25% dual chamber were analysed. One hundred and forty (43%) were in atrial fibrillation and were older, 80.5 +/- 7.1 years, compared with 75.5 +/- 11.4 years (P = 0.014) for those in sinus rhythm. Temporary pacemaker reprogramming was necessary in 86% in order to determine the abnormal rhythm. Thirty-nine (28%) of those in atrial fibrillation were anticoagulated; 37% were on aspirin; only 10.8% of those in atrial fibrillation who were not anticoagulated had contraindications to this therapy. Prevalence of atrial fibrillation increased with age, whereas that of anticoagulation decreased with age. In conclusion, the majority of pacemaker patients with atrial fibrillation, for whom anticoagulation is indicated, fails to receive it: those caring for these patients are urged to ensure its much wider use.

Aged↗
PubMed2000

DNA damage induced by radiation of different linear energy transfer: initial fragmentation.

PURPOSE: To investigate DNA fragmentation as a function of linear energy transfer (LET) after exposure to accelerated ions in the LET range 40-225 keV/microm. MATERIALS AND METHODS: Fragmentation patterns of double-stranded DNA in the range 5 kilobasepairs (kbp) to 5.7 megabasepairs (Mbp) were analysed after irradiation of low-passage GM 5758 normal human fibroblast cells with 60Co-photons, helium ions at 40 keV/microm and high-LET nitrogen ions between 80 and 225 keV/microm. Two separate pulsed-field gel electrophoresis protocols were used, optimized for separation of 1-6 Mbp and 5 kbp to 1.5 Mbp fragments. RESULTS: An increased probability of formation of short and medium-sized DNA fragments was revealed following high-LET irradiation. The DNA double-strand break (dsb) induction yields were, respectively, 5.8 and 6.9-8.8 x 10(-9) dsb bp(-1) Gy(-1) for 60Co-photons and ions. The ion yields were some 80-110% higher than those calculated according to a conventional approach, disregarding the fragment distributions. For photons, the yield was 13% higher. The corresponding relative biological effectiveness (RBE) of dsb induction was in the range 1.2-1.5. CONCLUSIONS: A significant non-random contribution to the number of dsb after irradiation with high-LET was confirmed by detailed fragment analysis using pulsed-field gel electrophoresis. The LET had a strong influence on the initial DNA fragment distribution, and hence also on the induction yields measured. However, when the LET was increased to the highest values studied for nitrogen ions, the yield decreased slightly.

Cells, Cultured↗
PubMed2000

Rejoining of DNA fragments produced by radiations of different linear energy transfer.

PURPOSE: To analyse the rejoining of DNA double-strand breaks (dsb) produced by high-linear energy transfer (LET) ions, with the specific focus on the influence, on the rejoining estimates, of the way dsb are distributed along chromosomes. MATERIAL AND METHODS: Low passages of normal human fibroblasts (GM5758) were irradiated with 60Co photons, 40 keV/microm helium ions or nitrogen ions with LETs of 80, 125, 175 and 225 keV/microm. The double-stranded DNA fragment distributions, ranging from 5 kbp to 5.7 Mbp, were assayed by pulsed-field gel electrophoresis after repair incubation for 0-22 h. RESULTS: The rejoining was biphasic and the half-times of the two phases were 15 min and 2-3h, respectively, and were independent of LET. Although the majority of breaks were rejoined by the fast phase, both the fraction of dsb rejoined by the slow phase and the fraction of unrejoined dsb at 20-22h increased with increasing LET. CONCLUSIONS: DNA fragment analysis detected LET-dependent differences in the amount of rejoining while the half-times were independent of LET. The majority of dsb were rapidly rejoined even after high-LET irradiation. If fragment-size distribution is not taken into account, both the fraction of breaks rejoined by slow kinetics, and the fraction of unrejoined breaks, can be overestimated when the LET is increased.

Cells, Cultured↗
PubMed2000

Comparison of pulsed versus continuous radiofrequency energy delivery: diameter of lesions induced with multipolar ablation catheter.

The aim of this study was to compare the efficacy of pulsed versus continuous RF energy delivery via multipolar ablation catheters. In vitro tests were performed in endomyocardial preparations of fresh bovine hearts in a both of physiological saline solution (37 degrees C) at constant flow conditions (1.5 L/min). The catheters were applied to the endocardium at a constant pressure. Energy was delivered pulsed (to 4 electrodes simultaneously, 5-ms duty cycle) or continuously (to each electrode separately). In vivo experiments were performed under fluoroscopy in eight anesthetized pigs, guided by endocardial electrograms to place the catheters in 22 different intraatrial positions. Lesion volume was calculated from measurements of the lesion diameter with a microcaliper. The homogeneity of the lesions was classified from 1 (highest) to 4 (least). More homogeneous linear lesions were produced in significantly less time with pulsed than with continuous energy delivery. There were no differences in electrode temperature or impedance values in vitro and in vivo. The results in the in vitro experiments were reproducible in the intact animal experiments. Significantly larger and more homogeneous linear lesions were created more rapidly with pulsed than with continuous energy delivery.

Animals↗
PubMed2000

Population genetic structure of brown trout (Salmo trutta L.) within a northern boreal forest stream.

Brown trout (Salmo trutta L.) population genetic structure and its temporal stability were studied within a small forest stream in central Sweden using five microsatellite loci. Both resident and migrating brown trout are present in the watershed. Tissue samples were collected from seven sections of the stream during two consecutive years. No differences were found in multilocus FST estimates between years within sections except in one case. Moreover, differences between age cohorts within sample sections were rare. The low interannual variation and the low heterogeny between cohorts is interpreted as indications of temporal stability. Pairwise multilocus FST estimates increased with increasing geographic distance, indicating isolation by distance. It is argued that the brown trout of the Färsån stream represent a population complex. The structure is probably maintained by precise natal homing and a limited, but important, amount of gene flow between closely situated sections within the stream supporting a stepping-stone model of gene flow.

Alleles↗
PubMed2000

Varieties of long-term outcome among patients in psychoanalysis and long-term psychotherapy. A review of findings in the Stockholm Outcome of Psychoanalysis and Psychotherapy Project (STOPP).

This paper reports the main findings of a large-scale study of subsidized psychoanalysis and long-term psychotherapy. More than 400 people in various phases, before, during and after subsidized psychoanalysis or long-term psychodynamic psychotherapy, were followed up for a period of three years with personal interviews, questionnaires and official statistics. Our analyses revealed progressive improvement the longer patients were in treatment--impressively strong among patients in psychoanalysis--on self-rating measures of symptom distress and morale. Improvement, however, was equally weak in both groups on a self-rating measure of social relations. Dosage factors (treatment duration and session frequency in combination) partly accounted for the outcome differences between those referred to psychoanalysis and those referred to long-term psychotherapy. Attitudes and ideals among therapists and analysts concerning the goals and means of psychotherapy were also associated with patient outcome, although in rather complex ways. A significant part of the outcome differences between patients in psychoanalysis and in psychotherapy could be explained by the adoption, in a large group of therapists, of orthodox psychoanalytic attitudes that seemed to be counterproductive in the practice of psychotherapy but not in psychoanalysis. It is suggested that this effect may be a negative transfer of the psychoanalytic stance into psychotherapeutic practice and that this may be especially pronounced when the attitudes are not backed up by psychoanalytic training.

Adult↗
PubMed2000

Binding of 125I after administration of 125I-EGF-dextran, 125I-EGF or 125I to human bladder cancer spheroids.

The binding of a targeting agent, 125I-EGF-dextran, to epidermal growth factor (EGF) receptors in tumour spheroids of a human bladder cancer cell line was studied. The accumulation of radioactivity was continuous up to at least 48 h in the peripheral cells of the spheroids, which in comparison with the binding pattern of 125I-EGF indicated that the cells had a limited capacity to degrade the EGF-dextran. The 125I-EGF-dextran was of two different sizes, 28 and 76 kDa, but this did not affect the binding patterns and the results were very similar. The EGF-dextran conjugates had qualities that are of interest for tumour targeting.

Animals↗
PubMed2000

The influence of lipophilicity on binding of boronated DNA-intercalating compounds in human glioma spheroids.

Five boronated DNA-intercalating compounds [5-ortho-carboranyl phenanthridinium (5-o-CP), 5-para-carboranyl phenanthridinium (5-p-CP), 6-para-carboranyl phenanthridinium, water-soluble boronated phenanthridinium and water-soluble boronated acridine (WSA1)], primarily developed for boron neutron capture therapy (BNCT), were analysed regarding their binding in cultured human malignant glioma spheroids. Comparisons were made with the corresponding DNA intercalators ethidium bromide and acridine orange. Octanol/phosphate buffered saline-water coefficients were determined for all compounds, and it was found that the most lipophilic (5-o-CP and 5-p-CP) were most toxic and accumulated high amounts of boron in monolayer cells. These compounds bound primarily in the outermost part of spheroids with poor penetration into the inner region, even after 2 days of continuous exposure. On the other hand, the most hydrophilic compound (WSA1) showed lower toxicity and lower boron accumulation in monolayer cells, and rapid binding in the inner region of spheroids. A reasonable explanation for this observation is that the lipophilic compounds interact mainly with lipophilic parts of the cells, like cellular membranes, and therefore rapidly binds to cells, preventing penetration and binding to cells in the deeper region of the spheroids. The possibility of using these compounds for BNCT are discussed.

Acridines↗
PubMed1999

Tests of functional limitations in fibromyalgia syndrome: a reliability study.

OBJECTIVE: To evaluate the reliability and discriminative ability of a test battery consisting of 7 tests designed for the assessment of functional limitations in patients with fibromyalgia syndrome (FMS). METHODS: The intrarater reliability of the test battery was evaluated for 15 women with FMS. Interrater reliability was calculated on 4 tests separately. Fifteen healthy women constituted a reference group. RESULTS: The intrarater coefficient of variation was < 8% for the shoulder range of motion tests, chair test, and 6-minute walk test, and < 21% for the shoulder endurance test, with correlation coefficients above 0.80 for all tests. Kappa was 0.70-0.80 for the hand-to-scapula tests. The interrater coefficient of variation was < 5% for shoulder range of motion. The performances of the FMS patients were significantly decreased in comparison with healthy subjects in all the tests except for the hand-to-scapula movement. CONCLUSIONS: All but 1 of the selected 7 tests were considered to possess acceptable intrarater reliability for use in FMS in clinical physical therapy practice.

Activities of Daily Living↗
PubMed1999

Acute myocardial infarction with cardiogenic shock on admission: incidence, prognostic implications, and current treatment strategies. Results from "the 60-Minutes Myocardial Infarction Project". ALKK ("Arbeitsgemeinschaft leitender Krankenhauskardiologen") Study Group.

Little data exist about current treatment strategies the efficacy of thrombolytic therapy and outcome of patients with acute myocardial infarction (AMI) presenting in cardiogenic shock (CS). Data from the German multicenter "60 Minutes Myocardial Infarction Project" were used to analyze a large number of patients with AMI and CS on admission and to compare those to patients without CS. Between July 1993 and September 1994 a total of 7,085 patients with AMI were registered. Out of these, 179 patients (2.5%) presented in CS (systolic blood pressure < 100 and heart rate > 100/min, resuscitated patients were excluded). Patients in CS were significantly older than patients without CS. Their in-hospital mortality was 47.1% compared with 12.4% in patients without CS (p = 0.001). The prevalence of the following clinical parameters was significantly higher in patients with CS than in those without CS: bundle branch block, prior MI, and a non-diagnostic ECG (all p < 0.05). Thrombolytic therapy was used in 36.3% of patients in CS and in 50.8% of those without CS (p = 0.001). The in-hospital mortality in patients with CS receiving thrombolytic therapy was significantly lower than in patients with CS who did not receive thrombolytic agents (33.3% versus 55.1%; p = 0.006). In daily clinical practice in Germany thrombolytic treatment is used in only 36.3% of patients with AMI presenting in CS on admission. The use of thrombolysis in CS on admission is associated with a lower in-hospital mortality.

Adult↗
PubMed1999

[Enzymatic markers of reperfusion in acute myocardial infarct. With data from the ISAM study].

Despite advances in therapy acute myocardial infarction is associated with a mortality rate of up to 30%. Early and complete reperfusion of the infarct related artery (defined as TIMI flow 3 at 90 minutes following therapy) as obtained with thrombolytic therapy in 50 to 80% of patients improves survival and enhances ventricular function. Failure to achieve recanalization should prompt further intervention (second attempt of thrombolysis or rescue-PTCA). Various cardiac markers known from diagnosing acute myocardial infarction or risk stratification in unstable angina pectoris have been assessed in their ability to predict successful reperfusion/failure of therapy. Following reperfusion creatinkinase (CK) and its isoform CK-MB, troponin and myoglobin show an early and rapid rise to a high maximum value with rapid normalization. For creatinkinase time to peak values of less than 9 hours or rates of increase of > 50 U/h (> or = 10 U/h for CK-MB activity) within the first 2.5 hours following thrombolysis have been suggested as useful indicators of successful reperfusion. The same applies for a troponin (T)slope > 0.5 ng/ml/h within the first hour (Table 5). The major limitation in applying either creatinkinase, troponin or even lactatdehydrogenase (LDH) is their comparatively late release (4 to 6 hours) following myocardial infarction. In that respect myoglobin (though not specific for cardiac injury) seems ideal for guidance of intervention after failed thrombolysis. The I.S.A.M. study included 1,741 patients with acute myocardial infarction of less than 6 hours duration being given either streptokinase or placebo. Serial blood samples for measurement of cardiac enzymes were drawn within the first 50 hours. In the streptokinase group the time to peak concentration of CK-MB activity was significantly lower (mean 10.9 hours vs 16.1 hours following initiation of treatment) as was the area under the CK-MB curve indicating reduction of infarct size (Table 2). A substudy investigating the myoglobin release in 120 patients having received streptokinase or placebo demonstrated higher maximum values in the streptokinase group (mean 3008 vs 2097 ng/ml), a shorter time to peak interval following treatment (3.4 vs 6.5 hours) and a reduction in infarct size as suggested by a smaller area under the myoglobin curve (17,377 vs 23,240 ng/ml x h) (Table 3). For LDH/alpha-HBDH the reduction in time to peak intervals was less impressive (Table 4). In angiographic studies with TIMI flow 3 at 90 minutes in the infarct related artery in 22 patients (Figure 5) the maximum myoglobin value was reached in less than 4.2 hours (mean value plus SEM) following treatment (9.5 hours for CK-MB activity). Therefore, myoglobin seems to be the preferred marker in reperfusion assessment.

Acute Disease↗
PubMed1999

Resolution of ST-segment elevation in acute myocardial infarction--early prognostic significance after thrombolytic therapy. Results from the COBALT trial.

In acute myocardial infarction, early identification of patients at a high mortality risk is important for planning further therapeutic strategies. Previous studies have demonstrated that the extent of early resolution of ST-segment elevation may represent a simple, quick and noninvasive assessment to identify high risk groups of patients. In a subgroup of the COBALT Study population (Continuous Infusion vs Double Bolus Administration of Alteplase), ST-segment elevation was measured before and 90 to 120 minutes after treatment with alteplase. The subgroup of n = 1,760 patients was not different from the total COBALT population of n = 7169 patients regarding most clinical parameters except Killip Class before treatment. However, the overall 30-day mortality differed significantly between the main study and the substudy (7.76% vs 3.52%; p < 0.001). Three groups of ST-segment resolution were defined: 1. complete resolution (resolution > or = 70%; 762 patients), 2. partial resolution (< 70% and > 30%; 491 patients), 3. no resolution (< 30%; 507 patients). Mortality rate at 30 days for complete, partial and no resolution of ST-segment elevation was 1.31%, 4.28% and 6.11%, respectively (p < 0.001). While this significant correlation between the extent of ST-segment resolution and mortality could be observed for inferior acute myocardial infarction, it could not be found in patients with anterior acute myocardial infarction. This in part may be due to a selection bias that leads to an extremely divergent mortality rate of anterior acute myocardial infarction in the main study and the substudy (10.1% vs 3.94%; p < 0.0001). Despite this limitation, resolution of ST-segment elevation in acute myocardial infarction after thrombolytic therapy allows to identify patients at a high mortality risk and may help to select patients for early invasive procedures such as PTCA. Patients with complete ST-segment resolution showed a particularly low mortality rate, irrespective of the alteplase regimen used (front-loaded alteplase vs double bolus alteplase).

Acute Disease↗
PubMed1999

The long-term prognosis of whiplash-associated disorders (WAD).

Somatic and mental symptoms in 22 patients (16 women and 6 men) 22-73 months after a whiplash injury are described. The results of the present study are compared with the corresponding results of a previous study on the same patients. According to the Quebec Classification System, the whiplash injuries of 15 patients were classified as grade 2 and those of 7 patients as grade 3. Pain intensity was evaluated by means of a visual analogue scale and muscular tenderness was assessed by pressure algometry. Algometry was also used to measure the pain tolerance level. The Mood Adjective Check List was used as a measure of mental well-being. During the 2 years that had passed since the previous study, the patients had improved regarding pain intensity, pain tolerance level and mental well-being. The results show that patients with prolonged disability after a whiplash injury can improve even after a long time.

Adaptation, Physiological↗
PubMed1999

High yield direct 76Br-bromination of monoclonal antibodies using chloramine-T.

Monoclonal antibody (MAb) A33 was labeled with the positron emitter 76Br (T(1/2) = 16.2 h). Direct labeling was done using the conventional chloramine-T method. After optimization of the labeling conditions, a maximum yield (mean +/- max error) of 77 +/- 2% was obtained at pH 6.8. In vitro binding of 76Br-A33 to SW1222 colonic cancer cells showed that the immunoreactivity was retained. Also, the MAbs 38S1 and 3S193 and the peptide hEGF were 76Br-labeled, resulting in labeling yields (mean +/- max error) of 75 +/- 3%, 63 +/- 4%, and 73 +/- 0.1%, respectively. We conclude that antibodies and peptides can be labeled conveniently with 76Br for the purpose of whole-body tumour imaging by positron emission tomography.

Antibodies, Monoclonal↗
PubMed1999

Self-assessment of well-being in a group of children with epilepsy.

Epilepsy is common in childhood, the prevalence being about five per 1000 children. The purpose of this study was to assess well-being in children with controlled epilepsy (but did not include those with obvious neurodeficits such as mental retardation or cerebral palsy) and compare them with age-matched healthy children. The patient group comprised of 31 children, 12 boys and 19 girls, whereas the control population group consisted of 342 children, 176 boys and 166 girls who were all in good health. All children involved in the study were aged between 9-13 years. A questionnaire was distributed to the children to complete. It consisted of 39 bipolar adjectives and a visual analogue scale was employed. The results show that the group of children with controlled epilepsy did not differ significantly from the age-matched control group. There was no significant difference between the sexes except for the dimension of vitality, where the boys scored better than the girls. Thus the well-being of children with controlled epilepsy seems to be similar to that of children from a control population. The psychometric properties of the instrument were also assessed. An assessment of well-being in children with intractable epilepsy, using a similar approach, is in progress.

Adaptation, Psychological↗