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Biomedical subjects

T Persson

Publications and source records attributed to T Persson.

At least 55 records · Page 3Linked to original sources
PubMed1996

Magnetic-field Exposures in the Workplace: Reference Distribution and Exposures in Occupational Groups.

Exposures to extremely-low-frequency magnetic fields were assessed by taking personal measurements with a dosimeter calibrated at 50 Hz with a bandwidth of 40-400 Hz. The study group was a population-based random sample of 1,098 Swedish men. Exposures were determined as workday mean, median, maximum, and standard deviation, and the time fraction of the day when exposures exceeded 0.20 µT. For workday means, the 50th percentile was 0.17 µT, and the 75th percentile was 0.27 µT. For median values, the 50th percentile was 0.11 µT and the 75th percentile was 0.16 µT. The strongest correlation (Spearman rank correlation = r&infs;) found was between the workday mean and the fraction of time above 0.20 µT (r&infs; = 0.89). The authors used the same data to estimate exposures for the 100 most common occupations according to the 1990 Swedish census. A minimum of four independent measurements for each occupation was required. Among occupations with low workday mean values were earth-moving machine operator, health care worker, and concrete worker. Among occupations with high workday mean exposures were welder and electrical or electronics engineer or technician. High exposure levels were also found in occupations outside the study base, such as train engine driver and glass, ceramic, or brick worker. Exposures to magnetic fields vary widely, since levels of exposure are strongly affected by factors such as duration of exposure and distance from the source. Large variations often found between individuals within occupations could reflect variations in tasks across different workdays for the particular occupations and/or local conditions such as tools and installations, and/or how the work is organized and performed.

Journal Article↗
PubMed1995

Can overconfidence be used as an indicator of reconstructive rather than retrieval processes?

In a recent paper Wagenaar (1988) suggested that overconfidence can be used as an indicator of reconstructive processes which allow responses based on inference to be distinguished from responses based on retrieval. The ecological models (Björkman, in press; Gigerenzer, Hoffrage, & Kleinbölting, 1991; Juslin, 1993a, 1993b, 1994) provide a more positive view of the calibration of reconstructive responses. In this paper we compare these two views and argue that overconfidence cannot be considered a reliable indicator of reconstructive processes since people may be well calibrated for tasks that require inference, provided that tasks are selected in offunbiased manner. Instead, we discuss two different models: the response-independence model which is appropriate to retrieval, and the response-dependence model which applies to inference. These two models predict different distributions of solution probabilities and they therefore provide a criterion by which we can distinguish between direct retrieval and reconstruction. In two empirical studies modelled after Experiment 1 in Wagenaar's (1988) paper it is shown that calibration can be very similar and quite reasonable both for tasks that are dominated by inference and tasks that are dominated by retrieval processes. In Experiment 2 we show that the two conditions nevertheless differ in regard to the distributions of solution probabilities in the manner predicted by the two response models presented in the paper. It is proposed that the issue of which is the most appropriate interpretation of solution probabilities is neglected, and that the criterion should be of interest also to applications outside the domain of calibration research.

Adult↗
PubMed1995

A marker-free method to estimate joint centre of rotation by video image processing.

A marker-free video measurement and image processing method that provides numerical estimation of the 2-D centre of rotation of one rigid segment is tested. The algorithm is based on binary region moment features. A comparison is made between this method and a marker-based one, where the location of the markers has been calculated in two ways. The algorithm is also extended to handle two rigid segments. The method is to be applied in human locomotion analysis in order to calculate the centre of rotation of the hip joint. It's accuracy has been tested by a comparison with in vivo radiological measurements on humans.

Adult↗
PubMed1995

Synthesis and antiviral effects of 2-heteroaryl substituted adenosine and 8-heteroaryl substituted guanosine derivatives.

2-(2"- and 3"-Thienyl)adenosine and the corresponding furyl derivatives were prepared though Pd(0)-catalyzed coupling of 2',3',5'-tri-O-(t-butyldimethylsilyl)-2-iodoadenosine with the appropriate tributyltin derivatives followed by deprotection. Preparation of the 8-(2"- and 3"-thienyl)guanosines and 8-(2"- and 3"-furyl)guanosines followed a similar route. Antiviral properties of these compounds and the related 2,6-diaminopurine ribofuranosides were of no pharmacological interest.

Adenosine↗
PubMed1994

Oral budesonide for active Crohn's disease. Canadian Inflammatory Bowel Disease Study Group.

BACKGROUND: Corticosteroids are the most efficacious drugs for inducing remission in active Crohn's disease, but their benefits are frequently offset by serious side effects. Budesonide is a corticosteroid with high topical antiinflammatory activity but low systemic activity because of extensive hepatic metabolism. We investigated the efficacy and safety of an oral controlled-ileal-release preparation of budesonide in patients with active Crohn's disease involving the ileum or ileum and proximal colon. METHODS: In a double-blind, multicenter trial, 258 patients were randomly assigned to receive placebo or one of three doses of budesonide--3, 9, or 15 mg daily. The primary outcome measure was clinical remission, as defined by a score of 150 or less on the Crohn's disease activity index. RESULTS: After eight weeks of treatment, remission occurred in 51 percent of the patients in the group receiving 9 mg of budesonide (95 percent confidence interval, 39 to 63 percent), 43 percent of those receiving 15 mg (95 percent confidence interval, 31 to 55 percent), and 33 percent of those receiving 3 mg (95 percent confidence interval, 21 to 44 percent), as compared with 20 percent of those receiving placebo (P < 0.001, P = 0.009, and P = 0.13, respectively). Improvements in the quality of life, as measured by the patients' responses to the inflammatory bowel disease questionnaire, paralleled these remission rates. Location of disease, prior surgical resection, and previous use of corticosteroids did not affect the outcome. A total of 119 patients (46 percent) were withdrawn from the study before the trial ended, 96 because of insufficient therapeutic effects, 13 because of adverse reactions, and 10 because of noncompliance. Budesonide caused a dose-related reduction in basal and corticotropin-stimulated plasma cortisol concentrations but was not associated with clinically important corticosteroid-related symptoms or other toxic effects. CONCLUSIONS: In an eight-week trial, an oral controlled-release preparation of budesonide at an optimal daily dose of 9 mg was well tolerated and effective against active Crohn's disease of the ileum and proximal colon.

Administration, Oral↗
PubMed1994

Effects of reducing or discontinuing inhaled budesonide in patients with mild asthma.

BACKGROUND: In a previous study, we found that two years of treatment with an inhaled corticosteroid, budesonide, was more effective than treatment with an inhaled beta 2-agonist, terbutaline, in patients with newly diagnosed, generally mild asthma. We continued this study for a third year to investigate whether the steroid dose could be reduced or discontinued and what effect crossover of patients from beta 2-agonist therapy to corticosteroid therapy would have. METHODS: A total of 37 patients treated for two years with inhaled budesonide at a dose of 1200 micrograms per day were randomly assigned to treatment with 400 micrograms of budesonide per day (19 patients) or placebo (18 patients) in a double-blind manner. Another 37 patients, who had received terbutaline during the first two years, were crossed over in an open-label manner to treatment with 1200 micrograms of budesonide per day during the third year. RESULTS: Treatment with the reduced dose of budesonide was sufficiently effective in 74 percent of the patients to maintain bronchial responsiveness at a level similar to that achieved with the higher dose. In contrast, improvement was maintained in only 33 percent of the patients receiving placebo, and the differences in pulmonary function between the steroid and placebo groups were significant (for forced expiratory volume in one second, P = 0.007; for bronchial responsiveness to histamine, P = 0.025; and for peak expiratory flow in the morning, P = 0.040). The condition of patients who were crossed over from terbutaline therapy to treatment with 1200 micrograms of budesonide per day improved. However, the degree of improvement in these patients appeared to be less than in those who were treated with budesonide at the beginning of the three-year study. CONCLUSIONS: Early treatment with inhaled budesonide results in long-lasting control of mild asthma. Maintenance therapy can usually be given at a reduced dose, but discontinuation of treatment is often accompanied by exacerbation of the disease.

Administration, Inhalation↗
PubMed1993

Occupational exposure to electromagnetic fields in relation to leukemia and brain tumors: a case-control study in Sweden.

Occupational exposure to low-frequency electromagnetic fields (EMF) was studied in 250 leukemia patients and 261 brain-tumor cases, diagnosed in 1983-87 and compared with a control group of 1,121 randomly selected men, from the mid-region of Sweden, 1983-87. We based the exposure assessment on measurements from 1,015 different workplaces. On the basis of the job held longest during the 10-year period before diagnosis, we found an association between the average, daily, mean level of EMF and chronic lymphocytic leukemia (CLL). The risk increased with increasing level of exposure. The odds ratios (OR) and the 95 percent confidence interval (CI) for three consecutive levels of exposure were: 1.1 (CI = 0.5-2.3); 2.2 (CI = 1.1-4.3); 3.0 (CI = 1.6-5.8), respectively. No association was observed for acute myeloid leukemia (OR = 1.0, CI = 0.5-1.8; OR = 0.8, CI = 0.4-1.6; OR = 1.0, CI = 0.6-1.9). For brain tumors, the corresponding risk estimates were 1.0 (CI = 0.7-1.6); 1.5 (CI = 1.0-2.2); 1.4 (CI = 0.9-2.1). Different EMF indices were tested. Tasks with frequent or large variations between high and low field-densities (high standard deviation) were more common among CLL subjects. For brain tumors, a prolonged high level (high median values) showed the strongest association. Confounding by place of residence, smoking, benzene, ionizing radiation, pesticides, and solvents was evaluated, and these factors did not seem to have a decisive influence on the associations. We also analyzed other potential sources of bias. For CLL, there were indications of an excess number of low-exposure subjects among non-responders, which, to some extent, may have enhanced but not caused the risk estimates obtained. Our conclusion is that the study supports the hypothesis that occupational EMF exposure is a hazard in the development of certain cancers.

Acute Disease↗
PubMed1992

A steroid enema, budesonide, lacking systemic effects for the treatment of distal ulcerative colitis or proctitis.

The aim of this study was to evaluate whether budesonide enema (2 mg/100 ml) had a significantly better effect than placebo in the treatment of distal ulcerative colitis or proctitis. The trial was of controlled, randomized, double-blind design and included 41 treated patients. The treatment time was 4 weeks, with revisits after 2 and 4 weeks. If no improvement was seen, the patient could be switched over to open-label therapy with budesonide enema. Sigmoidoscopy, histology, blood chemistry, and diary cards were used for estimating the effect of treatment. The results showed that budesonide was superior to placebo. Sigmoidoscopy and biopsy scores improved significantly (p less than 0.01) in budesonide-treated patients compared with placebo. Significantly more patients switched over to open budesonide treatment in the placebo group owing to lack of efficacy compared with budesonide (p less than 0.001). No drug-related adverse experiences occurred, and there was no decrease in endogenous morning plasma cortisol levels. It is concluded that budesonide enema appears to be an effective and safe treatment for distal ulcerative colitis and proctitis.

Administration, Topical↗
PubMed1992

Septic shock in rats treated with terbutaline alone and in combination with chemotherapeutics, dexamethasone, and infusion of 3% albumin.

The effects of a beta 2-receptor agonist, terbutaline, on haematocrit and survival were studied in rats in which septic shock had been induced by intraperitoneal injection of a mean (SD) dose of 6.0 (4.5) x 10(8) live E. coli. Untreated septic animals developed haemoconcentration, the mean (SD) haematocrit increasing from 47.5 (1.4) to 53.1 (2.2). Mean (SD) survival time was 8.9 (0.6) hours, and no animal survived for 24 hours. Terbutaline given as the only treatment in doses of 0.1, 0.5, and 2.5 mg/kg before injection of E. coli significantly reduced the haemoconcentration, with haematocrit of 51.9, 46.6 and 47.9, respectively, at 4 hours. Survival was not significantly prolonged. When terbutaline was started 5.5 hours after injection of E. coli and given in addition to a chemotherapeutic drug (trimethoprim + sulphamethoxazole) and dexamethasone, haematocrit were reduced, 24 hour survival improved from 44% to 68%, and 7 day survival improved from 20% to 48%. We conclude that terbutaline given alone counteracts the loss of plasma volume during septicaemia and, when combined with a chemotherapeutic and dexamethasone, significantly improves long term survival.

Albumins↗
PubMed1992

Budesonide in grass pollen rhinitis.

To determine the relative efficacy, to compare the incidence of adverse experiences, and to assess the systemic glucocorticoid effect of nasal preparations of budesonide, 200 micrograms bid, and placebo, 50 adult patients with seasonal allergic rhinitis due to grass pollen were studied in a stratified, double-blind parallel group design. After a 2-week baseline period, budesonide nasal spray, 100 microgram per nostril twice a day, was compared with placebo nasal spray over a 4-week treatment period. Supplementary treatment with chlorpheniramine, 4-mg tablets, was permitted when necessary to control symptoms. Daily symptom and medication diaries were kept by the patients. Investigator assessments of symptoms and side effects were made at clinic visits at 2-week intervals. At baseline and again towards the end of the study, blood samples were drawn for the determination of plasma cortisol levels and 24-hour urine samples collected for the measurement of 17-hydroxycorticosteroid output. Of the 24 men and 26 women entering, 49 completed the study. Symptom scores for sneezing, stuffy nose, and nasal secretion all decreased dramatically from baseline when budesonide treatment was started. The decrease in symptoms was greater for budesonide than for placebo (P < .001). There was no difference between budesonide and placebo with regard to eye itch and rescue medication used. Morning nasal washes were taken during the grass season before treatment was started and 16 to 17 days after. They showed a significant decrease in TAME esterase levels in secretions in the budesonide treated patients (P = .03) but not in the placebo-treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Comparison of a beta 2-agonist, terbutaline, with an inhaled corticosteroid, budesonide, in newly detected asthma.

BACKGROUND: The presence of airway inflammation even in mild asthma points to the potential value of antiinflammatory therapy. We compared the effect of an inhaled corticosteroid, budesonide, with that of an inhaled beta 2-agonist, terbutaline, in the long-term treatment of newly detected asthma. METHODS: We studied 103 patients (29 male and 74 female patients 15 to 64 years old) in whom asthma had appeared within the previous year. The patients were randomly assigned in blinded fashion to two treatment groups: one to receive 600 micrograms of inhaled budesonide twice a day, and the other to receive 375 micrograms of inhaled terbutaline twice a day. The study period was two years. RESULTS: After six weeks of treatment, the patients treated with budesonide tolerated inhaled histamine better than the patients treated with terbutaline (a difference of one doubling dose step, P less than 0.001), and the difference was sustained. Patients' diaries kept during the first three months of the study and during the last month of the first and second years showed budesonide to be more effective than terbutaline in improving peak expiratory flow in the morning (average increase from the pretreatment value, 32.8 liters per minute for budesonide vs. 4.8 liters per minute for terbutaline; P less than 0.001) and in the evening (P less than 0.01). Budesonide was also more effective in reducing the symptoms of asthma (P less than 0.01) and the use of supplemental beta 2-agonist medication (P less than 0.01). Ten patients were withdrawn from the terbutaline group because treatment was insufficiently effective, whereas only one dropped out of the budesonide group. The adverse reactions to both treatments were few and mild. CONCLUSIONS: Antiinflammatory therapy with inhaled budesonide is an effective first-line treatment for patients with newly detected, mild asthma, and it is superior to the use of terbutaline in such patients.

Adolescent↗
PubMed1991

Incidence of leukaemia and brain tumours in some "electrical occupations".

A 19 year follow up study was conducted to explore the association between occupations expected to be exposed to electromagnetic fields and the occurrence of leukaemia and brain tumours. Incidence of cancer between 1961-79 was calculated and the standardised morbidity ratio (SMR) with a 95% confidence interval (95% CI) was related to that of all Swedish working men. For all the selected "electrical occupations" the SMRs for total leukaemia and brain tumours were near unity. Increased risks were noted for all leukaemia among electrical/electronic engineers and technicians, (SMR 1.3; 95% CI 1.0-1.7) as well as in the sub-groups of telegraph/telephone (2.1; 1.1-3.6) and machine (2.6; 1.0-5.8) industries. Risk for chronic lymphoid leukaemia was increased in the same occupational category (1.7; 1.1-2.5) and in the sub-group of machine industry (4.8; 1.0-14.0), as well as for all linesmen (2.0; 1.0-3.5) and power linesmen (2.8; 1.1-5.7). Risk for acute myeloid leukaemia was increased among all miners (2.2; 1.0-4.1) and miners working in iron/ore mines (5.7; 2.1-12.4). Increased risk for all brain tumours (2.9; 1.2-5.9) and glioblastomas (3.4; 1.1-8.0) appeared among assemblers and repairmen in radio and TV industry. Raised risk for all brain tumours was seen for all welders (1.3; 1.0-1.7) and welders in iron/steel works (3.2; 1.0-7.4) and risk for glioblastomas was also increased for all welders (1.5; 1.1-2.1). No major changes in relative risk estimates were noted after the exclusion of persons who were over 65 at the time of diagnosis. Although a homogeneous pattern of increased risks of leukaemia or brain tumour was not noted, the hypothesis that magnetic fields might play a part in the origin of cancer cannot be rejected.

Adult↗
PubMed1989

Oxygen consumption and central hemodynamics in septic shock treated with antibiotics, fluid infusions, and corticosteroids.

The multidimensional pathophysiology of septic shock is poorly understood and treatment modalities are controversial. The present study evaluates the relative importance of three therapeutic measures: antibiotics (trimethoprim and sulphamethoxazole [TS]); fluid infusions (lactated Ringer's solution [RL] and 3% albumin [Alb]), and pharmacologic doses of corticosteroids (CS) (dexamethasone [DM]), using central hemodynamics (plasma volume [PV], cardiac output, oxygen consumption [VO2]), and survival as end-points. Septic shock was induced by intraperitoneal injection of live Escherichia coli bacteria. At 5 h in untreated septic rats, PV had dropped to 76%, cardiac output to 69%, and VO2 to 71% of preshock levels. Untreated septic animals had a mean survival time of 9.7 +/- 1.7 (SD) h, with none surviving 24 h. Regardless of therapy, cardiac output and VO2 at 10 h were predictors of survival time (p less than .01). Treatment was initiated at 5.5 h after bacterial injection, at a time when TS therapy alone had not improved the 24-h survival rate. Animals treated with DM, RL, and Alb, in this order, exhibited progressively improved central hemodynamics, and 24-h survival rate increased to 60% compared with 0 in untreated animals (p less than .001). The combination of DM and RL produced no further improvement. However, DM combined with 3% Alb restored VO2, cardiac output, and PV to 81%, 100%, and 125%, respectively, increasing the 24-h survival rate to 97% (29/30), significantly greater than that achieved by any other treatment modality (p less than .05).

Animals↗
PubMed1987

A controlled randomized trial of budesonide versus prednisolone retention enemas in active distal ulcerative colitis.

Sixty-four patients with active distal ulcerative colitis participated in a multicentre, randomized, investigator-blind trial to compare the effect of budesonide enema, 2 mg/100 ml, with prednisolone disodium phosphate enema, 31.25 mg/100 ml. Budesonide is a new potent corticosteroid with a rapid first-pass elimination. The patients were treated for 4 weeks, and the efficacy of the drugs were evaluated by sigmoidoscopy, histology, and subjective symptoms after 2 and 4 weeks. After 4 weeks of treatment 16 of 31 patients (52%) receiving budesonide enema had healed endoscopically, compared with 8 of 33 (24%) (p = 0.045) receiving prednisolone enema. Budesonide was superior to prednisolone in terms of both significantly improved sigmoidoscopic and histologic scores and subjective symptoms evaluated by visual analogue scales. The patients receiving prednisolone had a significant depression of endogenous cortisol levels during the treatment period, but not the patients receiving budesonide. Budesonide enema seems to be a promising therapy for active distal ulcerative colitis and causes no adverse reactions.

Adolescent↗
PubMed1986

Terfenadine in chronic urticaria: a comparison with clemastine and placebo.

Terfenadine, a new specific and peripherally acting antihistamine, was compared with clemastine and placebo in a prospective, randomized, double-blind, double-dummy, crossover study of the treatment of chronic urticaria. Sixty patients with chronic urticaria participated in this multicenter trial. The treatment time was two weeks per drug treatment, totalling six weeks. Terfenadine proved more effective than clemastine and was associated with significantly less sedation. Few adverse reactions were noted.

Adult↗
PubMed1985

Highly reiterated non-coding sequence in the genome of Plasmodium falciparum is composed of 21 base-pair tandem repeats.

Clones containing highly reiterated DNA sequences were isolated from a Plasmodium falciparum genomic library. One clone, Rep2, was selected for further characterization by nucleotide sequence analysis. The results revealed that the insert of this clone is composed of tandemly arranged 21 base-pair imperfect repeats. These repeats are estimated to comprise approximately 1% of the P. falciparum genome and there are 10(4) to 2 X 10(5) copies, depending on the genome size estimate used for calculation. Moreover, the repeats are organized in clusters and do not appear to be transcribed in non-synchronized P. falciparum cultures.

Cloning, Molecular↗
PubMed1984

Analysis of clinical specimens by hybridisation with probe containing repetitive DNA from Plasmodium falciparum. A novel approach to malaria diagnosis.

The capacity of a DNA probe containing cloned repetitive sequences from Plasmodium falciparum to identify malaria-infected blood samples was tested with a spot hybridisation assay. Parasitaemia levels of 0.001% could be detected in 50 microliters blood from patients. The probe correctly diagnosed P falciparum infection in patients from different continents and appeared to be specific for P falciparum, since it did not cross-react with three other Plasmodium species tested.

Base Sequence↗