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Biomedical subjects

E Hansen

Publications and source records attributed to E Hansen.

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

Light-induced oxidative changes in a model dairy spread. Wavelength dependence of quantum yields.

Light-induced formation of lipid peroxides in a water-in-oil emulsion based on purified rape-seed oil (80%) was found to increase with decreasing wavelength and to have the (apparent) quantum yields (1.1 +/- 0.1) x 10(-)(3) for 436 nm, (2.6 +/- 0.1) x 10(-)(3) for 405 nm, and (4.5 +/- 0.4) x 10(-)(3) for 366 nm irradiation, as determined after 12 h of exposure to monochromatic light of an approximate intensity of 10(18) quanta.min(-)(1).mL(-)(1) and related to total light absorption. Riboflavin (0.8 ppm) had no effect on lipid peroxidation, but photodegraded with a quantum yield ((1.5 +/- 0.3) x 10(-)(5) for 436 nm, (1.7 +/- 0.2) x 10(-)(5) for 405 nm and (1.39 +/- 0.09) x 10(-)(5) for 366 nm irradiation) independent of irradiation wavelength. beta-Carotene was only photodegraded to a minor extent, but protected riboflavin against photodegradation and the lipids against peroxidation for 436 and 405 nm irradiation (reduction in quantum yield three times for 4.5 ppm beta-carotene for lipid oxidation and more for riboflavin degradation), but not for 366 nm irradiation, where beta-carotene has an absorption minimum.

Dairy Products↗
PubMed2000

Vitamin D: should the supply in the Danish population be increased?

A working group was established to evaluate the need for an increased vitamin D intake in the Danish population. Vitamin D is primarily important for calcium homeostasis, calcium absorption in the intestine and calcium content in bones, and thereby for the strength of the bones. Only a few foods provide vitamin D and the intake in the Danish population is low compared to the recommendation. However, vitamin D is also produced by the skin from solar exposure. How much vitamin D is provided this way is not known but it is said to be the most important source. Measures of vitamin D status and clinical signs of vitamin D status are therefore important when assessing the possible need for increased vitamin D intake. Measures of vitamin D status have shown a low status in the elderly but not in the young. More than 50% of nursing-home residents have low blood vitamin D levels and many have biochemical signs of osteomalacia. Vitamin D deficiency increases the risk of osteoporosis. In Denmark, for instance, 13,000 admissions each year are caused by hip fractures alone, almost all among elderly people. Dark-skinned women often constitute a problem with respect to vitamin D sufficiency because of reduced production from the skin secondary to extensive covering, skin pigmentation and many hours spent indoors. It is concluded that the elderly and dark-skinned (veiled) women will benefit from an increased vitamin D supply. Four strategies to increase vitamin D supply were considered: dietary changes, increased solar exposure, dietary supplements with vitamin D and food fortification with vitamin D. It is concluded that the best solution is to recommend dietary supplements with vitamin D to elderly over 65 years, dark-skinned and veiled women and people who, because of disease, are unable to spend time outdoors.

Age Factors↗
PubMed2000

Popliteal fossa neural blockade as the sole anesthetic technique for outpatient foot and ankle surgery.

Foot and ankle operations are being performed with greater frequency as outpatient procedures. Although the surgical procedure remains the same whether the operation is done in an inpatient or an outpatient setting, the anesthesia and postoperative analgesia are greatly affected when patients must be discharged soon after their operation. We have evaluated a regional anesthetic technique which blocks the sciatic nerve in the popliteal fossa and the saphenous nerve block at the knee. This was the sole anesthetic technique for both the operation and the immediate postoperative period. This technique appears to have several advantages: 1) Excellent anesthesia during the operation and for about ten hours postoperatively; 2) Use of a proximal calf tourniquet, and 3) Absence of systemic or local complications as might be seen with general, spinal or epidural anesthesia.

Adult↗
PubMed2000

HMO malpractice: have the floodgates opened?

The U.S. Supreme Court's holding in Pegram v. Herdrich--that decisions by an HMO's physician employees in which eligibility issues and reasonable medical treatment are inextricably mixed are not fiduciary acts under the Employee Retirement Income Security Act (ERISA)--was applauded by the managed care industry. By delineating issues on which it was not ruling, however, the Court's decision may have given a boost to additional lawsuits against managed care plans on both ERISA and malpractice grounds.

Employee Retirement Income Security Act↗
PubMed1999

Gibberellins and Subapical Cell Divisions in Relation to Bud Set and Bud Break in Salix pentandra.

In young plants of Salix pentandra, a temperate zone deciduous woody species, elongation growth ceases and a terminal bud is formed at day lengths shorter than a critical length. This is the first step in dormancy development, making survival under harsh winter conditions possible. Early studies strongly indicate that gibberellin is involved in the photoperiodic control of bud set and bud break. GA(1) action was studied by application under short days to plants where cessation of shoot elongation had occurred, followed by subsequent anatomic investigations of shoot tips. Under short days the frequency of cell division decreased rapidly along with the earlier observed decrease in GA(1) levels. Application of GA(1) to short-day-induced terminal buds rapidly stimulated cell division in apices several days before visible shoot elongation in response to this treatment was observed. One day after GA(1) application a fourfold increase in cell division frequency in apices was observed, increasing to a maximum of sevenfold 2 days after application. Long-day treatment leading to induction of bud break after about 4-6 days was followed by slowly increasing frequency of cell divisions. In earlier studies of this species, short days and gibberellins had no effect on cell elongation. These data show that increased GA(1) content, by application or long-day treatment, results in increased frequency of mitosis. This strongly indicates that GA(1) affects stem elongation in connection with bud set and bud break primarily by affecting cell divisions in subapical tissues.

Journal Article↗
PubMed1999

Blood irradiation for intraoperative autotransfusion in cancer surgery: demonstration of efficient elimination of contaminating tumor cells.

BACKGROUND: Intraoperative blood salvage is contraindicated in cancer surgery because of contaminating tumor cells and the risk of systemic dissemination. On the basis of the radiosensitivity of cancer cells, irradiation of salvaged blood with 50 Gy is proposed as a way to allow return of salvaged blood. STUDY DESIGN AND METHODS: Elimination of tumor cells by blood irradiation was studied in vitro with cells from 10 cell lines and from 14 tumor preparations after their addition to red cells in high numbers, or with blood shed during cancer surgery. Before and after gamma radiation, tumor cells were isolated by density gradient centrifugation and tested for their proliferative capacity in a cell colony assay. DNA metabolism was analyzed by incorporation of 5' bromodesoxyuridine. RESULTS: Survival curves of cells from various tumors confirmed D0 (the dose required to reduce the fraction of surviving cells to 37 percent of the original value) values in the range of 1.2 to 2.2 Gy. After irradiation of tumor cell-contaminated blood with 50 Gy, no cell colony formation was observed, which indicates a reduction rate exceeding 10 log. Irradiated cancer cells showed viability, but no residual DNA metabolism. CONCLUSION: The level of inactivation by a 50-Gy dose far exceeds that needed to inactivate the number of proliferating tumor cells observed or expected in wound blood. These results provide the experimental basis for the clinical application of blood irradiation for intraoperative blood salvage in cancer surgery.

Blood↗
PubMed1999

A survey of postoperative pain treatment in children of 3-14 years.

There is a lack of information concerning the characteristics of pediatric postoperative pain in Southern European countries. The aim of this study was to document how postoperative pain in children was managed routinely at Spanish surgical wards.The study was carried out in three hospitals on the first postoperative day. Children were divided in four groups according to their age (years): Group I (3-5), II (6-8), III (9-11) and IV (12-14). The parameters evaluated were: analgesia characteristics (type of prescription, drug used and route of administration, prescribed dose and whether the drug was or was not administered, need of non-prescribed analgesics) and the postoperative pain intensity. The results were analysed using descriptive statistics. U-Mann Whitney, chi(2), ANOVA, Kruskall-Wallis and Student's t -test were also used.A total of 348 children ranging from 3 to 14 years were studied. The average age (+/- SD) was 8.2 +/- 3.3 and the majority were male (74%). Urologic surgery was the most frequent type of operation, with age (p<0.05) and hospital differences (p<0.001). The majority of the patients (52%) were prescribed an analgesic, but only 26% of them had an analgesia order at fixed dosage intervals. Differences among the hospitals were observed (p<0.001). The most commonly used analgesics were metamizol, propyphenazone, paracetamol and codeine. Differences in choice of drug in relation to age and hospital were significant (p< 0.001). Rectal was the preferred route of drug administration. Patient's age was unrelated with the prescribed analgesic dose. An average of 68% of prescriptions were given and half of the patients without scheduled analgesia needed to have analgesics administered. Around 20% of patients had high pain scores.Few paediatric patients are given analgesics at fixed dose intervals to treat postoperative pain. Pain relief therapy for children differs notably to that of adults, in respect to the drugs prescribed and the administered route. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.

Journal Article↗
PubMed1999

[High-resolution magnetoencephalography--studies with a small-volume phantom].

To investigate the spatiotemporal organisation of neuronal processes in an animal model using magnetoencephalography (MEG), a high temporal resolution (ms) and an appropriate spatial resolution of about 1 mm is necessary. With the aim of determining the localization error and the resolution power of high-resolution MEG systems, we developed a phantom capable of simulating the characteristics of animal models. The phantom enables us to variably position at least two magnetic field sources to within 0.1 mm. For source localization on the basis of the magnetic field data, a spatial filtering algorithm was used. The investigation of a 16-channel micro SQUID-MEG system with a current dipole orientated tangentially to the phantom surface produced the following localization data (min ... max, x, y--horizontal plane, z--depth); systematic localization error e(x) = 1.16 ... 1.67 mm, e(y) = -1.01 ... -1.28 mm, e(z) = -5.22 ... -7.64 mm, standard deviation of the individual measurements perpendicular to the dipole axis s(perp) = 0.05 ... 0.22 mm, along this axis s(long) = 0.20 ... 1.73 mm, in the depths sz = 0.17 ... 3.17 mm. The "goodness of fit" was > 95%. Separation of two dipoles was still possible for parallel dipoles at a distance apart of d(parallel) = 0.03 mm and for those oriented perpendicularly to each other at a distance apart of d(perp) = 0.10 mm. On the basis of these results we conclude that the MEG system can achieve a resolution sufficient to permit the investigation of neuronal microstructures. The spatial errors detected were related to sensor position in the cryostatic vessel as well as to external low-frequency noise.

Magnetoencephalography↗
PubMed1998

Application of the two-film theory to the determination of mass transfer coefficients for bovine serum albumin on anion-exchange columns.

The paper describes a method of simultaneous determination of the external and the solid-phase mass-transfer coefficients from frontal analysis data. The protein flux to the solid particles is determined from the slope of the breakthrough curve and the mass-transfer coefficients are determined by fitting the two-film model to the experimentally determined flux. The two-film model is compared with two apparent overall driving force models: the apparent overall mobile phase driving force model and the apparent overall solid-phase driving force model. The experiments show that the apparent overall driving force models fail to describe the flux correctly and this is substantiated by the theory. Results obtained with bovine serum albumin on the anion-exchange media Q HyperD, Source, and Poros show that the external film resistance is significant for Reynolds numbers less than one. The experimental Sherwood numbers are lower than expected and their dependence on the Reynolds number are much higher than expected.

Anion Exchange Resins↗
PubMed1998

A review of the incorporation of complementary and alternative medicine by mainstream physicians.

BACKGROUND: Studies suggest that between 30% and 50% of the adult population in industrialized nations use some form of complementary and/or alternative medicine (CAM) to prevent or treat a variety of health-related problems. METHOD: A comprehensive literature search identified 25 surveys conducted between 1982 and 1995 that examined the practices and beliefs of conventional physicians with regard to 5 of the more prominent CAM therapies: acupuncture, chiropractic, homeopathy, herbal medicine, and massage. Six studies were excluded owing to their methodological limitations. RESULTS: Across surveys, acupuncture had the highest rate of physician referral (43%) among the 5 CAM therapies, followed by chiropractic (40%) and massage (21%). Rates of CAM practice by conventional physicians varied from a low of 9% for homeopathy to a high of 19% for chiropractic and massage therapy. Approximately half of the surveyed physicians believed in the efficacy of acupuncture (51%), chiropractic (53%), and massage (48%), while fewer believed in the value of homeopathy (26%) and herbal approaches (13%). CONCLUSIONS: This review suggests that large numbers of physicians are either referring to or practicing some of the more prominent and well-known forms of CAM and that many physicians believe that these therapies are useful or efficacious. These data vary considerably across surveys, most likely because of regional differences and sampling methods, suggesting the need for more rigorous surveys using national, representative samples. Finally, outcomes studies are needed so that physicians can make decisions about the use of CAM based on scientific evidence of efficacy rather than on regional economics and cultural norms.

Acupuncture Therapy↗
PubMed1998

Volatile anaesthetics induce changes in the expression of P-selectin and glycoprotein Ib on the surface of platelets in vitro.

Halothane has been shown to inhibit platelet aggregation and may, therefore, prevent intraoperative platelet activation. The aim of this study was to compare the effects of volatile anaesthetics on platelet activation, including the transformation into an adhesive platelet phenotype. After in vitro exposure to volatile anaesthetics, the expression of the adhesion molecule P-selectin and the internalization of the receptor for the von Willebrand factor (GPlb) were analysed by flow cytometry. In contrast to desflurane or N2O, sevoflurane (> or = 0.5 MAC, P < 0.05), halothane (> or = 1.0 MAC, P < 0.01) and isoflurane (> or = 2.0 MAC, P < 0.01) induced a significantly higher expression of P-selectin on the surface of platelets, indicating the degranulation of alpha-granules. In the presence of desflurane (> or = 0.5 MAC, P < 0.05), halothane (> or = 1.0 MAC, P < 0.01), isoflurane and sevoflurane (both > or = 2.0 MAC, P < 0.01), a redistribution of GPlb occurred, indicating platelet activation. N2O had no effect. In conclusion, several of the volatile anaesthetics tested in vitro induced changes in the expression of P-selectin and GPlb, being characteristic of platelet activation. None of the anaesthetics investigated interfered with the platelet response to ADP stimulation.

Adult↗
PubMed1998

District court rules on Texas Health Care Liability Act.

The Health Care Liability Act, recently enacted in Texas, allows individuals to sue health insurance carriers, HMOs, and other managed care entities under certain circumstances. This article discusses the implications of the Act for managed care plans, including ERISA preemption.

Employee Retirement Income Security Act↗
PubMed1997

Reliability of dipole localization for the movement-evoked field component MEF I.

The movement-evoked field I (MEF I) component is the largest and most stable neuromagnetic component accompanying self-paced movements. In order to use MEG for studying dynamic changes in the cortical organization of movements, data about the reliability and variability of these neuromagnetic components for individual subjects must be established during different sessions. For this aim, three male subjects were requested to perform self-paced flexions of their index finger and thumb in repeated sessions while the MEG was recorded by a 31 channel system. The MEF I was identified for each session and a single equivalent dipole was calculated for this component. The dipole localizations of the various sessions were compared. The standard deviation of the localization for all persons and all values amounts to 4.0-5.2 mm for the three spatial dimensions. Our data suggest that the spatial distance between two single focal sources fitted to the MEF I must be greater than 14 mm to be interpreted as distinct. However, the neuromagnetic field structure and the resulting dipole localization of the MEF I component are quite stable and could be used for the evaluation of cortical plasticity.

Adult↗
PubMed1997

Assessment of isometric contractions performed with maximal subjective effort: corresponding results for EEG changes and force measurements.

In order to find a parameter or parameters that can be attributed to movements performed with maximal subjective effort, EEG recordings and force measurements were taken in connection with isometric muscle contractions performed with 80% of the subjective maximal force (IMC80) or with maximal subjective effort (IMC100). Criteria based on EEG recordings and force measurements have been considered as indicators for maximal subjective effort in a given movement. The following criteria were selected: A. If the mean spectral theta amplitude across the parieto-occipital area decreases from IMC80 to IMC100 then the isometric contraction is taken to be performed with maximal effort; B. If the obtained force values can be fitted to a switch function and if the achieved forces are only a predetermined percentage lower than the maximal force value obtained over all trials then this isometric contraction is accepted to be performed with maximal effort. 18 out of 24 cases fulfill the EEG criterion whereas the criterion for force measurements is fulfilled in 16 out of 24 trials. The comparison between the results obtained by means of the EEG criterion and by means of criterion for force measurement shows that the results are in agreement in 22 out of 24 cases (p < .001). The high correspondence of the assessments allows us to suspect that both criteria specify the same phenomenon, namely the performance of a motor task with maximal subjective effort.

Adult↗