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Biomedical subjects

S Sandberg

Publications and source records attributed to S Sandberg.

At least 73 records · Page 4Linked to original sources

Dry chemistry instruments in primary care. II. Comparison of users with non-users.

One way of studying the impact of dry chemistry desk-top instruments in primary care is by comparing users and non-users of this technology with respect to practice setting and changes in everyday practice, as well as to elucidate reasons for not implementing this technology. We therefore mailed a similar questionnaire to all users of the most-used dry chemistry instruments in Norway (n = 298) and to a 14% random sample of general practitioners (n = 381), and a 40% random sample of doctors in occupational health care units (n = 181). The response rate was 77-79% and 200 users and 281 non-users could be included. In general practice, more users were solo practitioners and more users had a cell counter in the office laboratory; fewer occupational health care users kept computerized records. Users reported improvement in diagnosis and treatment and claimed that patient satisfaction had improved. In general, an increase in the number of tests was estimated. Non-users were more pessimistic with regard to improvements in office laboratory service, and stated perceived problems regarding cost, workload and analytical quality as well as good service from the hospital laboratory as reasons for not implementing such instruments in their practice.

Attitude of Health Personnel↗

Assessment of psychosocial experiences in childhood: methodological issues and some illustrative findings.

The development of a new standardised investigator-based interview, PACE (Psychosocial Assessment of Childhood Experiences), for the assessment of acute life events and long-term psychosocial experiences is described. An application of PACE to a sample of 84 children referred to psychiatric clinics and 22 general population controls, is presented. Reliability was assessed using a separate clinic sample of 15 child-parent pairs. The findings showed that PACE has satisfactory reliability and discriminant validity.

Adaptation, Psychological↗

Circadian variation in serum cortisol and circulating neutrophils are markers for circadian variation of bone marrow proliferation in cancer patients.

Serum cortisol, circulating white blood cells and DNA cell cycle distribution in bone marrow cells were measured during daytime (11.00) and at midnight (24.00) over single 24-hour periods in 15 cancer patients. The neutrophils and fraction of bone marrow cells in S-phase showed the same circadian variation as cortisol with higher values in daytime as compared to midnight in 11 patients with a normal cortisol rhythm (p < 0.05). The lymphocytes, eosinophils and basophils all had significantly higher values at midnight as compared to daytime. There were significant correlations between cortisol and neutrophils, lymphocytes, eosinophils and basophils. The correlation between neutrophils and fractions of bone marrow cells in S-phase and S + G2/M-phase were highly significant (r = 0.74, p = 0.0001 and r = 0.72, p = 0.0001, respectively). In 8 of 13 patients (61.5%) without bone marrow infiltration both cortisol and neutrophils showed identical circadian variation as bone marrow cells in S-phase and S + G2/M-phase. Furthermore, for the total series a significant correlation between S-phase, cortisol and neutrophils was found by multiple regression analysis (p < 0.0001). These findings strengthen the possibility of using the circadian variation in cortisol and neutrophils as marker rhythms for circadian variation in bone marrow proliferation, thus allowing optimization of cytotoxic therapy and individualization of chronotherapy.

Adult↗

Hemoglobin oxygen affinity is increased in erythropoietic protoporphyria.

Whole blood and hemolysates from seven normal and three erythropoietic protoporphyria patients were compared in terms of their hemoglobin function. The oxygen affinity (P50) of the erythropoietic protoporphyria hemolysates compared to normals (13.1 +/- 0.2 vs 17.5 +/- 0.3 mmHg; P < 0.001) and erythropoietic protoporphyria erythrocytes compared to normals (23.4 +/- 0.6 vs 27.1 +/- 0.5 mmHg; P < 0.001) were increased while oxygen-binding cooperativity (n-value of the Hill equation) were similar. We conclude that hemoglobin function in erythropoietic protoporphyria patients is altered, but without pathophysiologic consequences. Because hemoglobin in which protoporphyrin IX substitutes for heme has a low oxygen affinity, our findings of a higher than normal affinity in erythropoietic protoporphyria red cells and hemolysates may indirectly support the findings by others that protoporphyrin IX binds to hemoglobin at non-heme-binding sites. In addition, based on the effect of other abnormal hemoglobins, this shift in P50 will decrease any tendency for anemia in erythropoietic protoporphyria patients.

Erythrocytes↗

High serum ferritin post partum: an acute phase reaction.

The purpose of the study was to examine the cause of the increased serum ferritin post-partum observed previously. B-hemoglobin, B-leucocytes, S-ferritin, erythrocyte protoporphyrin and S-orosomucoid were determined in the blood of 21 pregnant women in the 39th week of pregnancy, two to four days and six weeks after delivery. The S-ferritin was increased from 12.1 micrograms/l at the 39th week of pregnancy to 30.1 micrograms/l post-partum. The probable reason for this increment is an acute phase reaction since a rise in the concentration of S-orosomucoid and B-leucocytes were concurrently observed.

Acute-Phase Reaction↗

Clinical goals for measurement of hemoglobin in primary care as assessed by paper vignettes.

A random sample of 10% (273) Norwegian general practitioners (GP) received a questionnaire including 11 case stories. For each case the GP was asked to fill in an action value for hemoglobin which should represent the minimal change considered necessary by that general practitioner to take action towards the patient. These minimal changes could then be used for calculation of imprecision goals assuming that there was no change in the bias of the two measurements. The analytical imprecision goals (CV) derived from the different case stories varied between 0% and 7.8% with a mean of 2.8% accepting a false positive rate of 5%. The GPs assessment of a single case story also varied substantially.

Chemistry, Clinical↗

Comparison of the use of a dry chemistry analyser in primary care in Norway and the United Kingdom.

The results of a quality assessment survey of the most commonly used dry chemistry instrument in primary care in Norway and the United Kingdom, the Reflotron (Boehringer), are reported including an evaluation of some of the operational characteristics of the Reflotron users. The primary care users in Norway taking part in the study comprised 95 occupational health care departments and 89 general practices. In the UK, primary care users taking part were 95 occupational health care departments and 37 general practices. In terms of both accuracy and precision evaluation of concentrations of bilirubin, cholesterol, gamma-glutamyl transferase, glucose, triglycerides, urea and uric acid by primary care users was similar in the two countries, and to that of 60 Norwegian laboratories. Examination of operational characteristics revealed a lack of effective quality control measures in both countries, and some differences in the pattern of usage between primary care users in Norway and the UK, especially in general practice. The result of Reflotron tests were ready before the patient left in a considerably higher proportion of general practices in the UK than in Norway. It is concluded that the Reflotron is suitable for primary care use, but good, routine quality of analysis must be ensured through collaboration between primary care users and clinical chemists.

Blood Chemical Analysis↗

A comprehensive multiple matrix model representing the life cycle of the tick that transmits the agent of Lyme disease.

An extension of Leslie matrix methodology was developed to describe the life cycle of Ixodes dammini, the tick that transmits the agent of Lyme disease in eastern North America. Thereby, we described the seasonally changing pattern of interactions of the tick with its various hosts in a well-studied site on Nantucket Island, Massachusetts. Particular numerical values representing the site were estimated mainly on the basis of published values and interpreted on the basis of experience. The model was used to predict seasonal abundance and annual rate of increase of this vector tick. Although these ticks quest for hosts during two consecutive feeding seasons, all but a few feed during the first such season. The relative distribution of developmental stages of the tick stabilized after 35 years. Abundance of the simulated population increased exponentially and doubled every 6 years. The simulations produced realistic seasonal feeding distributions of the ticks in its various developmental stages.

Animals↗

Drinking habits and laboratory tests in seamen with and without chemical exposure.

The purpose of this study was to evaluate possible differences in drinking habits among seamen exposed to organic solvents and other hydrocarbon compounds compared to unexposed seamen. Information about alcohol consumption and alcohol-related problems was obtained by using an abbreviated version of the Michigan Alcoholism Screening Test, as well as additional questions about the quantity of alcohol consumption. Also, tests of serum gamma-glutamyl transferase and mean corpuscular volume were performed to reveal possible chronic toxic effects of chemical exposure and alcohol consumption, as physicians often use these blood tests in their health controls of seamen. The relationships between chemical exposure, age, smoking and alcohol consumption and results from blood tests were analyzed by using multiple regression analyses. Seamen exposed to organic solvents and other hydrocarbon compounds had more alcohol-related problems and more months of heavy drinking than did unexposed seamen. The previous year's alcohol consumption was similar in the two groups. A relationship between alcohol consumption and chemical exposure was not found. No correlation was found between chemical exposure and the results from the blood tests. Routine monitoring of gamma-glutamyl transferase and mean corpuscular volume did not seem useful in the evaluation of chemical hazards.

Adult↗

Activation of blood platelets in workers exposed to organic solvents.

Organic solvents probably exert their clinical effects through distortion of cellular membrane structure and function. Blood platelets represent an easily available membrane system. This study describes an evaluation of mean platelet volume (MPV) and total platelet count (TPC) in a group of workers exposed to a mixture of organic solvents in paint factories. We have found a correlation between decreased MPV and present exposure. The reduction was reversed within an exposure-free interval of 3 weeks. The intracellular adenosine triphosphate/adenosine diphosphate (ATP/ADP) ratio was significantly increased in exposed workers, compatible with dense granule secretion. A quantitative study of the phosphoinositide cycle in the platelets revealed an increased concentration of the phosphatidic acid, indicating an increased turnover. These findings are consistent with a solvent-induced activation of circulating platelets.

Adenosine Diphosphate↗

[Which laboratory tests should be performed by general practitioners--and how to assure good analytical quality?].

Near patient testing is increasing both in Norway and abroad. Having test results ready when the patient is present is beneficial in a number of clinical situations, as well as being efficient for both doctor and patient. However, the analytical quality in general practice has proved unstable and in many instances poor. Public expenditures to reimburse near patient tests are soaring. Therefore, high priority must be given to ensuring that the practitioner's laboratory is sound, both professionally and economically. The following items are considered important: All analytical work should be subjected to regular quality assessment. We list a number of constituents that are suitable for near patient analysis. The constituents are divided in two groups: those that all practices should be capable of analyzing, and constituents which should be analyzed in practices with doctors with a special interest in this field. We also suggest changes in the Norwegian public system of reimbursement for near patient testing.

Chemistry Techniques, Analytical↗

[What tasks should committees have for evaluating injuries to patients?].

Committees were established in 1983 to evaluate injury to patients in hospitals, in order to give an account of the course of events and the causal relation when damage does occur or patients forward complaints. The article reports on the work done at Haukeland hospital from 1984 to 1989. 472 cases of injury were reported. Many of these cases could have been prevented by better communication between doctor and patient. The number of cases reported to the Committee has increased considerably in recent years. At Haukeland hospital about one man-year is spent on work in the committee. After 1988 an increasing amount of the cases are cleared up by the Norwegian System of Compensation for Injuries to Patients. In the future the Committees for evaluation of injuries to patients in hospitals should work mainly to improve the reporting of such injuries, in order to ensure that patients receive adequate information, and to register injuries and accidents at each hospital.

Iatrogenic Disease↗

Mechanisms of photosensitivity in porphyric patients with special emphasis on erythropoietic protoporphyria.

In erythropoietic protoporphyria, protoporphyrin overproduction occurs mainly in erythroid tissue. Protoporphyrin can be released from erythrocytes in the dark, but the release is greatly increased if the erythrocytes are exposed to small amounts of light. Protoporphyrin can be bound in plasma either to albumin or to low density or high density lipoprotein. The cutaneous symptoms in erythropoietic protoporphyria are primarily elicited by protoporphyrin-sensitized photodamage of endothelial cells due to the presence of protoporphyrin in lipid structures. Which structures are damaged first in endothelial cells is unknown. Endothelial cells probably accumulate protoporphyrin from albumin or lipoproteins present in the plasma. A direct transfer from the erythrocyte membrane to the endothelial cell membrane can also occur. The transfer processes are probably facilitated by light exposure. Degranulation of mast cells, invasion of neutrophils into interstitial tissue and complement activation seem to be of less importance than endothelial cell injury in the pathogenesis of erythropoietic protoporphyria. These processes may, however, participate in the final expression of the cutaneous symptoms. Uroporphyrin and coproporphyrin are hydrophilic and are probably unbound in plasma, although weak binding to plasma proteins cannot be excluded. In the hepatic porphyrias and in erythropoietic porphyria, the clinical symptoms are probably evoked by uroporphyrin and coproporphyrin present in the interstitial tissue. Very little is known about the primary targets of uroporphyrin and coproporphyrin photodamage in these disorders, but photodamage to intercellular structures probably represents the initial event. Activation of complement may contribute to the final expression of the cutaneous symptoms.

Endothelium, Vascular↗

Clinical assessment of haemoglobin values by general practitioners related to analytical and biological variation.

Twelve case stories were mailed to 273 general practitioners to study the clinical assessment of haemoglobin values. For each case the general practitioner was asked to fill in the haemoglobin value representing the minimal change from a given value considered necessary to take action. haemoglobin change corresponding to the median haemoglobin value stated was transformed to a so-called 'medically useful coefficient of variation' in order to relate clinical demands to analytical and biological variation. The average medically useful coefficient was calculated to 3.9% (range 2.3-7.8%). We found that general practitioners assess haemoglobin values rather uniformly, although their judgement varies substantially with the clinical situation; they are not fully aware of the consequences of analytical and biological variation, and the advantage of knowing a previous haemoglobin value is not recognized. The analytical imprecision of haemometers based on clinical demands should be 2.8%, and the analytical quality should be the same in primary and secondary care.

Adult↗

Performance of cell counters in primary health care.

The results are presented from two external quality control surveys of cell counters in primary health care. The precision of haemoglobin measurements in the normal range was better than that obtained by conventional haemometers. The analytical quality of leucocyte analyses was about the same as that performed by hospital instruments. The precision of cell counters with respect to thrombocytes was poorer than that obtained on hospital instruments, especially in the lower level. Celldyn and Sysmex instruments performed best among the instruments examined. Reliable cell counter results were associated with medical laboratory technicians as operators of the instruments. To improve the analytical quality of the laboratory in primary health care, it appears necessary to establish an external quality assurance programme, including a laboratory consultancy service.

Blood Cell Count↗

Modeling the AIDS epidemic in Mexico City.

To study the future course of the AIDS epidemic in Mexico City, we use an open compartmental model to forecast new AIDS cases among homosexual and bisexual males and among heterosexual males and females. For each group three compartments are defined: uninfected persons, infected but asymptomatic persons, and persons diagnosed with AIDS. It is assumed that the AIDS epidemic will follow the propagation of infectious disease model, where spread of infection is proportional to the product of the number of healthy persons and the number of infected ones. The compartmental model is represented by a system of nonlinear differential equations describing the rate of change in the number of persons in each compartment. The impact of preventive measures is explored by decreasing the probability of HIV transmission, which is one of the model parameters representing behavioral patterns. By April 1989, 491 AIDS cases had been reported in Mexico City and classified as sexually related. Our model predicts that the AIDS incidence will continue to rise in Mexico City for the foreseeable future and will spread among the heterosexual population. Decreasing the transmission probability by 10% in all groups (through education programs) will result in a decrease of 18.1% in the number of accumulated cases over a 5-year period. A 20% decrease would prevent more than 31% of the cases. We conclude that mathematical models can be valuable in predicting the spread of the AIDS epidemic and the impact of behavioral change on its spread.

Acquired Immunodeficiency Syndrome↗

A new method for isolation of reticulocytes: positive selection of human reticulocytes by immunomagnetic separation.

A method for isolating pure reticulocytes from leukocyte-depleted blood of normal persons is presented. The separation was achieved using an immunomagnetic technique. A monoclonal mouse antibody against human transferrin receptor was bound to magnetic beads conjugated with sheep antimouse antibody. The recovery of reticulocytes from peripheral blood was 15% to 42%. Blood used for isolation of reticulocytes could be stored for 4 days at 22 degrees C without altering the yield of reticulocytes. At 37 degrees C incubation, the reticulocytes matured rapidly and the transferrin receptor was found to have a half-life of 16 hours. The activity of several enzymes and the amount of creatine and hemoglobin A1C were measured both in the reticulocytes and peripheral blood. Of the enzymes, porphobilinogen deaminase had the best discriminatory power with a ratio of 8.8 between reticulocytes and peripheral red blood cells. The ratio for creatine was 16.7. The ability to isolate pure human reticulocytes, released after normal erythropoiesis, will offer new possibilities in the study of these cells.

Adult↗