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Biomedical subjects

J Börjesson

Publications and source records attributed to J Börjesson.

28 records · Page 2Linked to original sources
PubMed1977

Creatine kinase B-subunit activity in human serum. II. Evaluation of s-ck b-subunit activity in the diagnosis of acute myocardial infarction.

In a group of 113 consecutive patients taken into a coronary care unit on suspicion of acute myocardial infarction, blood samples were taken every 6 h and the following enzyme activities were measured: creatine kinase (S-CK), aspartate aminotransferase (S-ASAT), alanine aminotransferase (S-ALAT) and lactate dehydrogenase (S-LD). All measurements were made according to the Recommendations of the Scandinavian Committee on Enzymes. On all patients S-CK B subunit activity was determined by immunoinhibition with a specific anti CK M-subunit inhibitory antibody. At peak values of the respective total enzyme activities CK and LD isoenzymes were further qualitatively estimated by electrophoresis. The data indicate that even serial determinations of total CK, ASAT, ALAT and LD activities in serum do not provide the information required for a conclusive diagnosis of myocardial infarction in the individual case. In contrast, the positive predictive value (PV) of S-CK B was found to be 1.0 and the negative predictive value was 0.98. S-CK MB showed a PV pos. of 1.0 and also a PV neg. of 1.0. Electrophoretic determination of S-LD isoenzymes was slightly poorer with a PV pos. of 0.96 and PV neg. of 0.98. S-CK, total activity with nearly 9 per cent false positives had a positive predictive value of only 0.91, but a negative one of 1.0.

Acute Disease↗
PubMedDate not supplied

Toxicology; in vivo x-ray fluorescence for the assessment of heavy metal concentrations in man.

x-Ray fluorescence (XRF) analysis and neutron activation analysis (NAA) are the two main methods for non-invasive in vivo determination of heavy metal concentrations in man. This paper describes various XRF-techniques developed for the measurements of cadmium, mercury and lead, primarily in occupationally exposed persons. Measurements have revealed cadmium concentrations close to 400 micrograms/g in the kidneys of exposed workers. Today, the technique can also be used for measuring kidney cadmium levels in the general population. Significantly different cadmium concentrations between groups of smokers and non-smokers have been observed. For workers with current lead exposure, there is no correlation between lead in finger bone and lead in blood. However, for retired lead workers, there is a relation between these levels, due to the endogenous excretion of lead from the skeleton. From a longitudinal study of retired lead workers, the biological half-time for bone lead was estimated to about 16 yr. Recently, the XRF-technique was shown to be capable of measuring mercury in vivo. On a group of chloralkali workers, we found kidney mercury concentrations ranging from non-detectable to over 50 micrograms/g.

Cadmium↗
PubMedDate not supplied

Improving the in vivo X-ray fluorescence (XRF) measurement of renal mercury.

In vivo polarised X-ray fluorescence (XRF) measurements of renal mercury have previously been reported (Börjesson J, Barregård L, Sällsten G, Schütz A, Jonson R, Alpsten M, Mattsson S, 1995. In vivo XRF analysis of mercury: the relation between concentrations in the kidney and the urine. Phys. Med. Biol. 40, 413-426). However, with the detection limit reported therein, this system is limited to measurements in cases of significant mercury exposure. An improvement in detection limit is desirable to produce a tool capable of occupational monitoring in cases of mild to moderate exposure. Therefore, design changes have been investigated to improve system performance. Through Monte Carlo simulation and experiment, optimal parameters were determined with respect to polarisation and filtration, as well as the ideal X-ray tube voltage. The optimal configuration will be discussed. A preliminary comparison in terms of minimum detectable limit (MDL) will be made with the preceding polarised XRF renal mercury system.

Filtration↗
PubMedDate not supplied

In vivo XRF as a means to evaluate the risk of kidney effects in lead and cadmium exposed smelter workers.

The effect on kidney function was studied in 22 smelter workers with concomitant exposure to lead and cadmium. One active and five retired workers showed early signs of kidney dysfunction. They all had a long-term and high lead exposure, while their kidney cadmium concentrations measured in vivo by XRF techniques were low to moderate. Thus, the exposure to lead has been a greater risk, although an interaction between lead and cadmium could not be excluded.

Acetylglucosaminidase↗
PubMedDate not supplied

Effects of lead on the endocrine system in lead smelter workers.

In this study of the effects of lead on the endocrine system, 77 secondary lead-smelter workers (i.e., 62 active and 15 retired) were compared with 26 referents. Lead concentrations were determined in plasma with inductively coupled plasma mass spectrometry (i.e., index of recent exposure), in blood with atomic absorption spectrophotometry, and in fingerbone with K x-ray fluorescence technique (i.e., index of long-term exposure). In addition, pituitary hormones were determined in serum by fluoroimmunoassay, and thyroid hormones and testosterone in serum were determined with radioimmunoassay. Nine lead workers and 11 referents were challenged with gonadotrophin-releasing hormone and thyrotrophin-releasing hormone, followed by measurements of stimulated pituitary hormone levels in serum. Median levels of lead in plasma were 0.14 microg/dl (range = 0.04-3.7 microg/dl) in active lead workers, 0.08 microg/dl (range = 0.05-0.4 microg/dl) in retired lead workers, and 0.03 microg/dl (range = 0.02-0.04 microg/dl) in referents (1 microg/dl = 48.3 nmol/l). Corresponding blood lead concentrations were 33.2 microg/dl (range = 8.3-93.2 microg/dl), 18.6 microg/dl (range = 10.4-49.7 microg/dl), and 4.1 microg/dl (range 0.8-6.2 microg/dl), respectively. Respective bone lead levels were 21 microg/gm (range = -13 to 99 microg/gm), 55 microg/gm (range = 3-88 microg/gm), and 2 microg/gm (range = -21 to 14 microg/gm). Concentrations of basal serum hormone (i.e., free thyroid hormones, thyrotrophin, sex hormone binding globulin, and testosterone) were similar in the 3 groups. There were no significant associations between the hormones mentioned herein and blood plasma, blood lead, and bone lead levels. In the challenge test, stimulated follicle-stimulating hormone levels were significantly lower in lead workers (p = .014) than in referents, indicating an effect of lead at the pituitary level. Also, there was a tendency toward lower basal stimulated follicle-stimulating hormone concentrations in lead workers (p = .08). This effect, however, was not associated with blood plasma level, blood lead level, or bone lead level. In conclusion, a moderate exposure to lead was associated with only minor changes in the male endocrine function, particularly affecting the hypothalamic-pituitary axis. Given that sperm parameters were not studied, the authors could not draw conclusions about fertility consequences.

Adult↗
PubMedDate not supplied

Lead in fingerbone: a tool for retrospective exposure assessment.

Exposure to inorganic lead may cause many adverse health effects. When absorbed, lead is accumulated in large part in bone. In this study, we investigated the relationship between lead concentration in fingerbone, exposure time, and lead in blood. We also sought to design a model that made it possible to use fingerbone lead as an indicator of earlier exposure. The study comprised 137 active workers from a secondary lead smeltery. Workers had undergone regular determinations of blood lead (i.e., up to 6 times/y) for up to 24 y. In addition, during the period 1979-1992, workers underwent up to four fingerbone lead assessments via noninvasive x-ray fluorescence. We calculated cumulative blood lead, adjusted for time-related reduction of bone lead according to a transfer of lead from bone to blood, for each worker. We obtained the best fit of bone lead to cumulative adjusted blood lead when we assumed a 14-y half-time for the transfer coefficient. This half-time was similar to the terminal half-time for lead in bone in retired smelters, whom we studied earlier by longitudinal in vivo measurements. We described models for the accumulation of bone lead on blood lead and exposure time. The combined data on bone lead and exposure time may be used to estimate a mean blood lead during previous exposure. Such estimates will be valuable in epidemiological studies aimed at evaluating the toxic effects of long-term lead exposure in lead workers for whom data on previous blood lead levels are lacking.

Adolescent↗
PubMedDate not supplied

Digital chest radiography with a large image intensifier. Evaluation of diagnostic performance and patient exposure.

A digital system for chest radiography based on a large image intensifier was compared with a conventional film-screen system. The diagnostic performance was evaluated with special reference to the digital monitor images with a modified version of receiver operating characteristic (ROC) analysis--free response ROC (FROC) analysis--on a chest equivalent phantom. Measurements of spatial resolution and energy imparted were also performed. The detectability of low-contrast objects as well as spatial resolution was better for the full-size film-screen radiographs than for both the digital monitor images and the 100 mm photofluorograms. The image-intensifier system has a potential for considerable dose savings in relation to the conventional technique provided that fluoroscopy is excluded in the positioning of the patients.

Energy Transfer↗