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Biomedical subjects

S Sandberg

Publications and source records attributed to S Sandberg.

At least 55 records · Page 3Linked to original sources
PubMed1998

Within-subject biological variation of reticulocytes and reticulocyte-derived parameters.

Automation of reticulocyte counting has decreased the analytical imprecision of this parameter. This has made it possible to use the number of reticulocytes and its derived parameters (reticulocyte maturity and reticulocyte cell indices) in new diagnostic and monitoring situations. For rational use of these parameters, it is important to have knowledge of their biological variability. The biological variability of reticulocytes and its derived parameters was studied in 13 healthy people during a period of 7 wk on 2 different instruments. The within-subject coefficient of variation for the reticulocyte count was about 11%, for the mean reticulocyte volume, mean reticulocyte haemoglobin content and mean reticulocyte haemoglobin concentration it was between 1 and 2%, whereas the coefficient of variations for the subpopulations of reticulocytes with different maturity varied depending on the method used for the measurements. The critical difference, that is the change in a result making it significantly different from the previous result, was about 35% for the reticulocyte count and 5-8% for the reticulocyte cell indices, making these indices excellent to follow changes in erythropoiesis. With a possible exception for the mean reticulocyte volume, the within-subject variation was small compared to the between-subject variation.

Adult↗
PubMed1997

Use and usefulness of laboratory handbooks.

The aim of this study was to investigate how reference handbooks distributed by hospital laboratories are used by medical doctors, and to what extent this kind of information can influence or change doctors' work habits. We also wanted to see if books with various contents of information are valued differently by the users, and we asked for preferences for an ideal book. A questionnaire was sent to 2075 medical doctors served by five Norwegian hospital laboratories. The overall response rate was 66%, of whom 76% had received a handbook. Seventy-eight percent of respondents who stated that they had received a handbook kept it in their consulting room and 45% used it once or more weekly. The majority (89%) found the books beneficial in their everyday work. Many doctors (36%) claimed that they had changed their routines as a result of the information in the book. The way of interpreting test results was influenced most often, followed by indications for ordering laboratory tests, sample collection and specimen handling, and patient preparation. Nearly all respondents (97%) felt that handbooks of this kind are beneficial to their technical and nursing staff. The results show that handbooks distributed by medical laboratories are well received, frequently used and highly appreciated by medical doctors. Comprehensive books are rated higher than smaller books.

Education, Medical, Continuing↗
PubMed1997

Systematic reviewing in laboratory medicine. Position Paper from the IFCC Committee on Systematic Reviewing in Laboratory Medicine.

Each year a vast number of biomedical articles and books are published and based on the articles reviews are written. Such reviews should be performed in a systematic manner. Systematic reviewing is a new discipline with its own methods for locating, appraising, and summarizing primary studies. Such methods have also been developed for studies on diagnostic test evaluations. It is important for the laboratory disciplines to engage in this work. IFCC has established a Committee for Systematic Reviewing in Laboratory Medicine. This committee will work to promote the understanding, the use and the performance of systematic reviewing.

Clinical Chemistry Tests↗
PubMed1996

[Quality of hemoglobin and glucose analysis in general practice. Results from the NOKLUS (Norwegian Health Authority) surveys 1994].

In 1992 the Norwegian health authorities and the Norwegian Medical Association initiated a joint project to secure the quality of laboratory analyses performed in primary health care. Two coordinated activities were established: in each of the 19 Norwegian counties a medical laboratory adviser was engaged, linked to the central clinical chemistry laboratory in that county. These advisers assist general practitioners and primary care specialists in securing the quality of laboratory procedures performed on their own premises. In addition, a Norwegian centre for external quality assurance in primary care (Norwegian abbreviation NOKLUS) was established. In 1994 NOKLUS had about 1,600 participants (comprising 95% of the relevant general and specialist practices). Tolerated limits are based on target intervals combined with a percentage tolerated deviation. Fresh material is used for haemoglobin, and target values are determined by two independent laboratories using the reference method. The article describes the results of the surveys of glucose and haemoglobin tests in 1994.

Blood Glucose↗
PubMed1996

Erythropoietic protoporphyria: two populations of reticulocytes, with and without protoporphyrin.

Erythrocytes from patients with erythropoietic protoporphyria contain large amounts of protoporphyrin. The photosensitivity experienced by these patients is assumed to be due to a leakage of protoporphyrin from the erythrocytes and transfer to the skin, where protoporphyrin acts as a photosensitizer. The leakage of protoporphyrin from the erythrocytes has been offered as an explanation for the great variety in protoporphyrin content observed among erythrocytes in this disease. Based on density gradient separation of red cells, it has been concluded that all reticulocytes and young erythrocytes contain large amounts of protoporphyrin. From our results, density gradient centrifugation is not suitable for age separation of red cells from patients with erythropoietic protoporphyria. By developing a new method for isolation of reticulocytes and applying flow cytometry to determine protoporphyrin content in individual cells, it was observed that two populations of reticulocytes were present in patients with erythropoietic protoporphyria, one with and the other without protoporphyrin. The half-life of protoporphyrin in red cells was found to be 12-14 days, in contrast to 1-2 days described previously, suggesting a slower release of protoporphyrin from the red cells than previously anticipated.

Cell Separation↗
PubMed1996

Hyperkinetic or attention deficit disorder.

BACKGROUND: In the face of rapidly expanding empirical knowledge about this common childhood condition, there is a need for an up-to-date synthesis, especially for the use of practising clinicians. METHOD: The main epidemiological, experimental and clinical studies over the past decade are selectively reviewed. RESULTS: Hyperkinetic/attention deficit hyperactivity disorder is common, with young school-age males most frequently affected. The prevalence figures vary depending on the criteria used. Overlap with conduct disorder is high. The causes are likely to stem from a combination of biological, often genetically determined neurochemical disturbances, and environmental disadvantages, with the biological risk tending to be highest in severely hyperactive girls. Good clinical management combines pharmacological, psychological and educational approaches in a sustained manner. Even then, the outcome is often equivocal and the long-term psychosocial adaptation unpredictable. CONCLUSIONS: Clinically significant hyperactivity is rooted in biological, often genetically transmitted vulnerabilities, upon which environmental disadvantages transect. It may be viewed as a disorder of self-regulation with its roots partly in strained early caregiver-child interactions and disrupted primary attachments.

Attention Deficit Disorder with Hyperactivity↗
PubMed1995

Lead in tissues of deceased lead smelter workers.

Smelter workers are exposed to a number of metals and other substances in dust, fumes and gases. The concentrations of lead in liver, lung, kidney, brain, hair and nails were determined in 32 deceased, long-term exposed male lead smelter workers, and compared with those of 10 male controls. The lead levels in liver, lung, kidney and brain were analyzed by atomic absorption spectrophotometry. X-ray fluorescence was used for the determinations in hair and nails. Lead in blood had been determined repeatedly in the lead workers since 1950, which made it possible to calculate a time-integrated blood lead index for each worker. The highest lead levels in soft tissues were found in liver, followed in order of concentration by kidney, lung and brain, among both exposed workers and controls. These organ lead concentrations were all significantly higher among the workers as compared with the control group (p < or = 0.02). The largest difference between workers and controls was found in brain tissue (ratio between median values = 5.6). The lead levels in hair and nails were of the same magnitude in the two groups. The workers showed positive correlations between lead concentrations in liver and kidney (Spearman's rho = rs = 0.59; p < 0.001), liver and hair (rs = 0.51; p = 0.003), liver and nails (rs = 0.52; p = 0.002) and hair and nails (rs = 0.52; p = 0.002). Lead concentrations in kidney correlated well with lead levels in hair (rs = 0.57; p = 0.001) and nails (rs = 0.51; p = 0.003), respectively. The positive correlation between the lead concentrations in liver and kidney indicates that these organs belong to the same soft tissue lead pool in the body. In retired lead workers, positive correlations were observed between the lead concentrations in liver and the cumulative blood lead index (CBLI) (rs = 0.50; p = 0.016), as well as between lead levels in kidney and CBLI (rs = 0.51; p = 0.014).

Aged↗
PubMed1994

Phenotyping autologous red cells within 1 day after allogeneic blood transfusion by using immunomagnetic isolation of reticulocytes.

BACKGROUND: When a transfused patient develops multiple or weak blood group antibodies, posttransfusion phenotyping is useful in antibody identification. To perform a correct phenotyping after transfusion, isolation of autologous red cells is necessary. However, mature autologous red cells are impossible to separate from their donor counterparts. Since the proportion of autologous reticulocytes compared to donor reticulocytes increases rapidly after transfusion, selective isolation of reticulocytes provides autologous cells for antigen typing. STUDY DESIGN AND METHODS: Extensive phenotyping was performed on red cells from 10 surgical patients before transfusion and on red cells and reticulocytes after the transfusion of 5 or more red cell units. Reticulocytes were isolated by using an antibody against the human transferrin receptor coupled to magnetic beads. RESULTS: The data showed nearly full agreement between pretransfusion phenotyping of red cells and posttransfusion typing of reticulocytes. Correct phenotyping of transferred patients could be obtained 8 to 10 hours after transfusion using isolated reticulocytes. CONCLUSION: This method is helpful in selecting compatible blood when patients have developed antibodies and have an urgent need for further transfusions.

Blood Grouping and Crossmatching↗
PubMed1994

The erythrocyte sedimentation rate in general practice: clinical assessment based on case histories.

Thirteen case histories were mailed to 273 general practitioners to study the clinical assessment of the ESR. Participants were asked to state their reference limits for the ESR, as well as action values for the ESR in several clinical situations typical of primary care. The action value should represent the minimal ESR change from a given value necessary to initiate some kind of action towards the patient. The response rate was 76%. In most case histories, half the general practitioners reacted on an ESR change of 10 mm h-1 or less, which is usually due to analytical and biological variation, thus underlining the need for good analytical quality. In general the response was of the same magnitude irrespective of type of case history, i.e. whether the ESR was used in case finding, in diagnosis, or in follow-up. Estimation of the reference limit displayed considerable variation, and knowledge of a previous 'normal' ESR was of minor clinical importance. Furthermore, we found substantial variation regarding the change in ESR necessary to take action in different clinical situations. In principle, for many general practitioners the action value increased as the given ESR increased whereas others reacted on a constant change in ESR, or the change necessary to take action depended on the clinical situation. We conclude that both the different assessments as to the clinical significance of the ESR, and the unawareness of the significance of analytical and biological variation indicate that guidelines for rational use are needed.

Adult↗
PubMed1994

Survey of office laboratory tests in general practice.

OBJECTIVE: To describe the types of laboratory test done in general practice, and to investigate whether practice characteristics were associated with the implementation of certain tests or instruments. SETTING: A questionnaire was mailed to an 8% random sample of Norwegian GPs. RESULTS: 85% responded; and we obtained data from 175 office laboratories. Medical secretaries did most of the analytical work. The "basic" repertoire consisted of haemoglobin, ESR, glucose; urine test strips, microscopy, culture, and HCG; and faecal occult blood. Group practices had a larger repertoire than had solo practices. Overall, 34% of the practices had urine strips with fields for leucocytes and nitrite, 26% had a cell counter, and 17% did clinical chemistry. A large number of different test methods and instruments were in use, but in most cases one or two brands had a market share of more than 50%. Logistic regression showed that employing a medical laboratory technician was associated with a large analytical repertoire, and the use of cell counters and clinical chemistry analyzers. The GP's form of payment (fixed or fee-for-service) did not influence the repertoire. CONCLUSIONS: The diversity of test methods and instruments makes quality assurance difficult, and recommendations are overdue.

Clinical Laboratory Techniques↗
PubMed1993

[Reticulocytes--new possibilities with automated counting].

A fully automated reticulocyte counter, Sysmex R-1000 has been evaluated at three Norwegian hospitals. The instrument measures fluorescence-labelled RNA in the reticulocytes by flow cytometry. It also generates information on reticulocyte maturity. Instrument precision was superior to that achieved with the routine visual counting method. Samples preserved at room temperature remain stable for one day, whereas samples preserved at 5 degrees C remain stable for four days. An increasing number of reticulocytes is often the first sign of marrow regeneration after bone marrow transplantation or treatment of leukaemia with cytostatica. In patients with chronic renal failure who are receiving erythropoietin, the increase in reticulocytes is seen within days, and precedes the increase in haemoglobin by 2-3 weeks.

Blood Specimen Collection↗
PubMed1993

Comparison of transmission rates of HIV-1 and HIV-2 in a cohort of prostitutes in Senegal.

To explore the biological similarities and differences between the HIV-1 and HIV-2 viruses, we model the probability of male-to-female transmission of either HIV virus as a function of the number of sexual partners, the prevalence of the viruses and the infectivity per contact. Using maximum likelihood estimation theory and data from a prospective study of registered female prostitutes in Dakar, Senegal, we estimate and compare the infectivities of HIV-1 and HIV-2. Graphical goodness-of-fit methods are used to show that our model fits the data well. We find that in male-to-female transmission HIV-1 is significantly more infectious than HIV-2. This finding is consistent with other data from laboratory and epidemiologic studies comparing the biology of HIV-1 and HIV-2.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Performance of the Reflotron and the Seralyzer in primary health care.

Results from an external quality control of 212 Reflotron and 19 Seralyzer primary care users are presented and compared with performance in 60 hospital laboratories. Respondent deviation was assessed by testing for differences in the distribution of individual deviations from an assigned value for hospital laboratories, or from a general average of the measurement procedure for the Reflotron or the Seralyzer users respectively. Respondent deviation in the Reflotron group matched hospital laboratory deviation, whereas deviation in the Seralyzer group was larger for aspartate aminotransferase, cholesterol and potassium. Seralyzer deviation was larger compared with Reflotron deviation. Imprecision was better in the hospital group than in the Reflotron group for alanine aminotransferase, aspartate aminotransferase, bilirubin, and creatinine whereas Reflotron users performed better than hospitals and Seralyzer users for uric acid; the Seralyzer group was inferior to hospitals for aspartate amino-transferase and potassium. The analytical quality of a subgroup of 138 Reflotron and 18 Seralyzer primary care users was assessed and these users were divided into 'good' and 'other' categories. Good performance was associated independently with use of the Reflotron, with operation by laboratory educated personnel, and with doing comparably few analyses per week. We conclude that the Reflotron is suitable for primary case use whereas the Seralyzer is less suitable.

Blood Chemical Analysis↗
PubMed1993

Dry chemistry instruments in primary care. I. Operating conditions and financial considerations.

The objectives of this study were to describe the operating conditions of dry chemistry instruments in primary care, as well as to elucidate financial aspects in general practice fee-for-service settings. We used questionnaires mailed to all users of the two most used dry chemistry instruments in Norway, as well as to a 14% random sample of Norwegian GPs. The overall response rate was 79%. The mean number of dry chemistry analyses varied considerably between individual users, but in general a substantial number of analyses were carried out. Even though most analyses on the instruments' repertoire were available in all user groups, a total of 13 additional constituents were suggested to be included in the repertoire. In occupational health care most results were ready when the client was present; this was not the case in general practice. The instruments were more profitable when more constituents were analysed per sample, although profitability varied substantially in the period studied (1986-1989). A discrete time history event analysis revealed that net profit earned, lower instrument price, available information about the technology and being in solo practice significantly influenced the decision to buy an instrument in fee-for-service practices.

Blood Chemical Analysis↗