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Biomedical subjects

S Sandberg

Publications and source records attributed to S Sandberg.

At least 37 records · Page 2Linked to original sources
PubMed2000

The role of acute and chronic stress in asthma attacks in children.

BACKGROUND: High levels of stress have been shown to predict the onset of asthma in children genetically at risk, and to correlate with higher asthma morbidity. Our study set out to examine whether stressful experiences actually provoke new exacerbations in children who already have asthma. METHODS: A group of child patients with verified chronic asthma were prospectively followed up for 18 months. We used continuous monitoring of asthma by the use of diaries and daily peak-flow values, accompanied by repeated interview assessments of life events and long-term psychosocial experiences. The key measures included asthma exacerbations, severely negative life events, and chronic stressors. FINDINGS: Severe events, both on their own and in conjunction with high chronic stress, significantly increased the risk of new asthma attacks. The effect of severe events without accompanying chronic stress involved a small delay; they had no effect within the first 2 weeks, but significantly increased the risk in the subsequent 4 weeks (odds ratio 1.71 [95% CI 1.04-2.82], p < or = 0.05 for weeks 2-4 and 2.17 [1.32-3.57], p < or = 0.01 for weeks 4-6). When severe events occurred against the backdrop of high chronic stress, the risk increased sharply and almost immediately within the first fortnight (2.98 [1.20-7.38], p < or = 0.05). The overall attack frequency was affected by several factors, some related to asthma and some to child characteristics. Female sex, higher baseline illness severity, three or more attacks within 6 months, autumn to winter season, and parental smoking were all related to increased risk of new exacerbations; social class and chronic stress were not. INTERPRETATION: Severely negative life events increase the risk of children's asthma attacks over the coming few weeks. This risk is magnified and brought forward in time if the child's life situation is also characterised by multiple chronic stressors.

Acute Disease↗
PubMed2000

[Guidelines for diagnosis and treatment of acute urinary tract problems in women].

BACKGROUND: Available guidelines for the management of symptoms of lower urinary tract infections (UTI) in women give conflicting recommendations. MATERIAL AND METHODS: We searched The Cochrane Library, Medline and other sources for evidence that met explicit inclusion criteria for the relevant options and outcomes identified. The validity of included studies was assessed. Draft recommendations were widely circulated and discussed in focus groups with patients and physician assistants. RESULTS: The probability that a woman with dysuria or frequency has bacteriuria, is 80%. The probability of UTI given a negative result of a dipstick test is 50%. Evidence suggests that antibiotics will rapidly relieve symptoms, but there are limited data from placebo-controlled randomised trials. Population based studies show that many women do not visit physicians for symptoms of UTI. Women with symptoms of UTI can be treated with antibiotics without examination of the urine. Women with earlier episodes of UTI can be offered treatment by telephone. Antibiotics for three days is sufficient based on eradication of bacteriuria. Women should be seen by a physician if the symptoms are atypical. INTERPRETATION: Implementing these guidelines could result in better service to women with UTIs. More evidence about the effects of antibiotics and other treatments is needed.

Anti-Bacterial Agents↗
PubMed2000

[Guidelines for diagnosis and treatment of sore throat].

BACKGROUND: Available guidelines for the diagnosis and treatment of sore throat give conflicting recommendations. Our aim was to develop evidence-based guidelines. MATERIAL AND METHODS: We searched The Cochrane Library, Medline and other sources for systematic reviews and other evidence that met explicit inclusion criteria for all of the relevant options and outcomes we identified. The validity of included studies was assessed. Draft recommendations based on assessment of this evidence were widely circulated and discussed in focus groups with patients and physician assistants. RESULTS: Throat infections are self-limiting and complications rare. Penicillin shortens the duration of symptoms in tonsillitis caused by beta-haemolytic streptococci and reduces the risk of complications. Penicillin has adverse effects and increases the risk of reinfections. Patients with sore throat should usually be treated without antibiotics. Visiting a physician is normally unnecessary. Antibiotics should be considered in serious cases or if the patient prefers this, but should only be prescribed for throat infections caused by beta-haemolytic streptococci. The diagnosis should be based on clinical criteria and a rapid antigen test in cases of doubt. INTERPRETATION: Benefits of antibiotics must be weighed against harms. Patients should be given good information and involved in decision-making if they want antibiotics.

Anti-Bacterial Agents↗
PubMed2000

Modulation of functionally active endothelin-converting enzyme by chronic neutral endopeptidase inhibition in experimental atherosclerosis.

BACKGROUND: Endothelin-converting enzyme-1 (ECE-1) processes big endothelin-1 (ET-1) to ET-1, a peptide implicated in atheroma formation. ECE-1 exists in 2 isoforms (ECE-1alpha and ECE-1beta), the result of alternative splicing of a common gene. Neutral endopeptidase (NEP) is a genetically distinct metallopeptidase that degrades the natriuretic peptides. These peptides mediate antiproliferative and vasodilating actions. We sought to demonstrate the distribution of the 2 ECE-1 isoforms in experimental atherosclerosis, to determine the effects of chronic NEP-I on plasma cGMP concentrations, vascular wall ECE-1 activity, and ET-1 concentration, and to correlate these actions with atheroma formation. Our hypothesis was that chronic NEP-I, in association with augmented cGMP, would inhibit ECE-1 conversion of big ET-1 to active ET-1, thus reducing tissue ET-1 concentrations and associated atheroma formation. METHODS AND RESULTS: Cholesterol-fed New Zealand White rabbits (n=8, 1% cholesterol diet) and NEP-I-treated cholesterol-fed New Zealand White rabbits (n=8; candoxatril, 30 mg/kg per day, Pfizer) were euthanized after 8 weeks of feeding. ECE-1alpha and ECE-1beta immunoreactivity was present in the aortas of both groups. Compared with control values, plasma cGMP concentrations were increased (2.8+/-0.6 versus 8.4+/-1.2 pmol/mL, P<0.05), ECE-1 activity was attenuated (68+/-3% versus 32+/-8%, P<0. 05), aortic tissue ET-1 concentrations were reduced (4.6+/-0.5 versus 3.2+/-0.3 pg/mg protein, P<0.05), and atheroma formation was attenuated (62+/-6% versus 34+/-5%, P<0.01) by NEP-I. CONCLUSIONS: These studies suggest that ECE-1 is present and functionally active in the vascular wall in atherosclerosis. Inhibition of ECE-1 by NEP-I represents a novel approach to interruption of the endothelin system in this cardiovascular disease state.

Animals↗
PubMed2000

Automated counting of white and red blood cells in the cerebrospinal fluid.

The objective of this study was to examine to what extent the automated method of the Bayer H*2 instrument could replace the visual counting of white and red blood cells in cerebrospinal fluid. The number of white blood cells as well as the percentage of mononuclear and polymorphonuclear cells were counted in the 'Baso channel' (Research screen 3) whereas the number of red cells were registered as the 'R-count' (Research screen 1). All automated cell counts were compared to visual estimates. The automated count yielded reliable results down to 5 x 106 white blood cells/l and 5 x 108 red blood cells/l. In some samples 'noise' was present in the Baso channel. A correct white blood cell count could then be obtained by counting the cells directly as dots on the screen. It was possible to differentiate between polymorphnuclear cells and mononuclear cells at all WBC concentrations. The automated counting of cerebrospinal fluid can be performed without changing thresholds or sample volumes of the instrument. Thus, in the routine practice it will be possible to alternate between automated counting of whole blood samples and cerebrospinal fluid samples.

Adult↗
PubMed2000

Use and interpretation of HbA1c testing in general practice. Implications for quality of care.

We evaluate the interpretation and use of HbA1c results in general practice in relation to diabetes follow-up and case-finding. As part of an external quality assurance scheme for laboratory analyses, two case histories were mailed to all Norwegian GPs with equipment for HbA1c analysis in their office laboratory (n=566) and to a random sample of GPs without such instruments (n=419). Patient A represented a monitoring situation and the GPs were asked to state changes in HbA1c signifying any improvement or deterioration of metabolic control. The initial HbA1c value stemmed from analysis of quality control material in the instrument group and was a preset value for the other group. In patient B, we focused on the use of HbA1c and other laboratory tests in diabetes case-finding. In the monitoring situation, 22% of GPs in the instrument group misclassified changes in HbA1c values, since these were less than the analytical uncertainty. Further, when interpreting HbA1c results, 64-93% of GPs (i) assumed that analytical quality was better than it really was, (ii) did not appreciate biological variation of HbA1c, or (iii) acted on small differences to be on the safe side. In case-finding, HbA1c was deemed important by 29% of GPs; doctors choosing not to perform a glucose tolerance test relied more on HbA1c. GPs have to be aware of analytical quality and biological variation when interpreting HbA1c results. The present limitations of HbA1c in the diagnosis of diabetes are not properly understood.

Aged↗
PubMed2000

A model for setting analytical quality specifications and design of control for measurements on the ordinal scale.

A model for characterization of measurements on the ordinal scale is presented. It is based on transformation of the calculated fractions (fractiles) of positives from measurements on samples with known concentrations to a probit-natural log (probit-ln) scale. Such measurements could be made by other methods on ratio or difference scales but, for convenience (for example for speed or low cost), are measured on the ordinal scale by "simple" methods. The model is examined, and verified, using three examples from published data (haemoglobin, glucose, and leukocytes) and an external quality assessment survey on measurements of streptococcus. We show that it is possible to obtain reliable analytical quality specifications and to establish design of control systems for measurements on the ordinal scale. It is concluded that the presented probit-ln model for the ordinal scale is a tool which can improve and facilitate (i) characterizing methods with measurements on the ordinal scale, (ii) defining analytical quality specifications, (iii) designing external assessment as well as internal control schemes, (iv) validation of methods with measurements on the ordinal scale according to the analytical quality specifications, and further, (v) reduction of the number of samples required for method validation and the number of replicate measurements needed.

Animals↗
PubMed1999

The susceptibility to nephrotoxicity of streptozotocin-induced diabetic rats subchronically exposed to cadmium chloride in drinking water.

Streptozotocin-induced diabetic rats and normal non-diabetic (ND) rats were exposed to cadmium chloride in drinking water in doses of 0, 50 and 100 ppm for 90 days. There was a dose-related increase in urinary protein and enzymes in the diabetic group, but an increase in proteinuria only in the high exposure subgroup of the ND group. It is suggested that diabetic rats induced by streptozotocin are more susceptible to cadmium nephrotoxicity than normal (ND) rats. Metallothionein synthesis in liver was estimated to be similar in both the diabetic and non-diabetic groups after exposure to cadmium. Less excretion of cadmium in urine and greater accumulation of cadmium in kidney were observed in the diabetic group, and this may be one of the mechanisms underlying the susceptibility of diabetic animals to the effects of cadmium. Further biochemical and histological studies are required in order to explain the detailed events involved in inducing such changes in the toxicokinetics of cadmium.

Acetylglucosaminidase↗
PubMed1999

Quality specifications derived from objective analyses based upon clinical needs.

The well-informed physician should be the best to judge the analytical quality needed for a specific clinical action. By presenting the physicians with well-designed case histories, it is possible to extract the clinical knowledge pertinent to analytical quality. The clinicians are asked which changes in the concentration of an analyte will cause them to change actions concerning the patient. It must be possible to detect these changes with a certain probability and this presupposes a certain analytical quality which can then be calculated. It is important that a strict methodology both for constructing case histories and for calculation of the required analytical quality is used.

Clinical Laboratory Techniques↗
PubMed1999

The index of individuality is often a misinterpreted quantity characteristic.

The concept of the "index of individuality" was introduced by Eugene Harris in 1974. The index of individuality, calculated as (CV(A)2 + CV(I)2)(1/2)/CV(G), where CV(A), CV(I), and CV(G) are analytical, within-subject, and between-subject coefficients of variation respectively, has been used by many to investigate the utility of conventional population-based reference values. For a high index of individuality, > 1.4, it has been said that reference intervals will be more useful than for a low index, < 0.6. The validity of these concepts is investigated here and a number of our findings are at odds with the generally held opinion. The index of individuality has no impact on the fraction of individuals classified using population-based reference values, as long as the change in concentration from the usual state is of the same absolute magnitude and one sample is assayed to detect disease. However, when a measurement falling outside a reference limit is repeated in order to verify the finding, the index of individuality has considerable influence. For quantities with very low indices, the repeat test result, will be close to the first and give no new information, whereas for quantities with high indices, a repeat test will decrease the number of true positives and false positives.

Biometry↗
PubMed1999

Cobalamin deficiency in general practice. Assessment of the diagnostic utility and cost-benefit analysis of methylmalonic acid determination in relation to current diagnostic strategies.

Diagnosing cobalamin deficiency is often difficult. We investigated the diagnostic strategies that 224 general practitioners used to assess cobalamin status and the criteria on which they based their decisions to supplement patients. From all serum cobalamin analyses carried out at a single laboratory during 1993, individuals with serum cobalamin concentrations <300 pmol/L were identified, and one patient per general practitioner was included. When serum methylmalonic acid (s-MMA) values >0.376 micromol/L were used as the "reference standard" for cobalamin deficiency, the serum cobalamin assay had a diagnostic sensitivity of 0.40 and a specificity of 0.98. With the same reference standard, the diagnostic accuracy of the physicians' decision to supplement patients had the same specificity but a higher sensitivity (0.51). Cost-benefit analysis indicated that measurement of s-MMA can be recommended in patients with serum cobalamin >60-90 pmol/L and <200-220 pmol/L, depending on its diagnostic accuracy.

Adolescent↗
PubMed1998

[Better quality of thrombotest in family practice. Results from the NOKLUS survey 1993-97].

The Norwegian centre for external quality assurance of primary health care laboratories (Norwegian abbreviation: NOKLUS) was established in 1992. In 1997 about 1,800 practices participated in NOKLUS' quality assurance schemes, and 576 of these participated in the PT survey. Participation is voluntary and free of charge. The interlaboratory variation (CV%) was 17.7% in 1993 and 13.3% in 1997, and the percentage of results classified as "poor" has decreased from 7-8% in 1993 to 4% in 1997. These data indicate that participation in the scheme has led to a widespread improvement in laboratory performance. Norwegian primary health care practices now seem to analyse PT just as accurately as the Norwegian hospital laboratories. Logistic regression showed that the two most important factors for ensuring quality analysis were having a medical laboratory technician perform the PT analyses, and using an analyzer rather than a manual procedure.

Family Practice↗
PubMed1998

Independence of childhood life events and chronic adversities: a comparison of two patient groups and controls.

OBJECTIVE: To examine the differences between independent and behavior-dependent stressful life events and chronic adversities in child psychiatric patients, community controls, and children with asthma. METHOD: The Psychosocial Assessment of Childhood Experiences was used to assess recent severe events (life events with high long-term threat) and major adversities (long-term experiences with high negative impact on child) in children attending a psychiatric clinic (n = 99), community controls (n = 26), and children with chronic asthma (n = 94). RESULTS: In the previous year, the psychiatric patients had, on average, experienced significantly more independent and behavior-dependent severe events and major adversities than either the controls or the asthmatic patients. The differences were most pronounced in relation to behavior-dependent high-threat life events and long-term-experiences. Among the psychiatric patients, one third of all severe events and one quarter of all major adversities were dependent on the child's behavior. The corresponding proportions in the controls and children with asthma were between one fifth and one twelfth. CONCLUSIONS: Psychiatrically disturbed children have an increased risk of experiencing behavior-dependent life events and long-term adversities compared with their peers in the community at large and compared with children suffering from a chronic physical illness such as asthma. Future studies need to examine the possible contributions of such experiences to the development and maintenance of psychiatric and physical illness in children.

Adolescent↗