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Biomedical subjects

S Holm

Publications and source records attributed to S Holm.

At least 19 recordsLinked to original sources
PubMed2007

High hopes and automatic escalators: a critique of some new arguments in bioethics.

Two protechnology arguments, the "hopeful principle" and the "automatic escalator", often used in bioethics, are identified and critically analysed in this paper. It is shown that the hopeful principle is closely related to the problematic precautionary principle, and the automatic escalator argument has close affinities to the often criticised empirical slippery slope argument. The hopeful principle is shown to be really hopeless as an argument, and automatic escalator arguments often lead nowhere when critically analysed. These arguments should therefore only be used with great caution.

Bioethics↗
PubMed2005

PET/CT with intravenous contrast can be used for PET attenuation correction in cancer patients.

PURPOSE: If the CT scan of a combined PET/CT study is performed as a full diagnostic quality CT scan including intravenous (IV) contrast agent, the quality of the joint PET/CT procedure is improved and a separate diagnostic CT scan can be avoided. CT with IV contrast can be used for PET attenuation correction, but this may result in a bias in the attenuation factors. The clinical significance of this bias has not been established. Our aim was to perform a prospective clinical study where each patient had CT performed with and without IV contrast agent to establish whether PET/CT with IV contrast can be used for PET attenuation without reducing the clinical value of the PET scan. METHODS: A uniform phantom study was used to document that the PET acquisition itself is not significantly influenced by the presence of IV contrast medium. Then, 19 patients referred to PET/CT with IV contrast underwent CT scans without, and then with contrast agent, followed by an 18F-fluorodeoxyglucose whole-body PET scan. The CT examinations were performed with identical parameters on a GE Discovery LS scanner. The PET data were reconstructed with attenuation correction based on the two CT data sets. A global comparison of standard uptake value (SUV) was performed, and SUVs in tumour, in non-tumour tissue and in the subclavian vein were calculated. Clinical evaluation of the number and location of lesions on all PET/CT scans was performed twice, blinded and in a different random order, by two independent nuclear medicine specialists. RESULTS: In all patients, the measured global SUV of PET images based on CT with IV contrast agent was higher than the global activity using non-contrast correction. The overall increase in the mean SUV (for two different conversion tables tested) was 4.5+/-2.3% and 1.6+/-0.5%, respectively. In 11/19 patients, focal uptake was identified corresponding to malignant tumours. Eight out of 11 tumours showed an increased SUVmax (2.9+/-3.1%) on the PET images reconstructed using IV contrast. The clinical evaluation performed by the two specialists comparing contrast and non-contrast CT attenuated PET images showed weighted kappa values of 0.92 (doctor A) and 0.82 (doctor B). No contrast-introduced artefacts were found. CONCLUSION: This study demonstrates that CT scans with IV contrast agent can be used for attenuation correction of the PET data in combined modality PET/CT scanning, without changing the clinical diagnostic interpretation.

Adult↗
PubMed2005

Radiation doses to staff involved in sentinel node operations for breast cancer.

BACKGROUND: The use of radioactive compounds for sentinel node biopsy is now a generally accepted part of the surgical treatment of breast cancer and melanoma, with the risk of radiation exposure to the operating team. The aim of this investigation was to study the levels of this exposure in relation to the permissible radiation dose limits. METHODS: The radiation exposure to the hands and bodies of the operating surgeons (the 'risk persons') was measured by thermoluminescent dosimeters in 79 operations and to the pathologists handling the specimens in 17 cases. Radioactivity and dose rate measurement from tumours and breast specimens were also performed. RESULTS: During an operation the mean skin dose (+/-SD) to the thermoluminescent dosimeters placed at the hand and the abdominal wall were 0.04 +/- 0.04 mSv (79 operations) and 0.01 +/- 0.02 mSv (67 operations) respectively. For the pathologist, the mean hand dose per operation was below the detection limit (17 operations). Correlation between the measured dose rate and the radioactive content of the tumours was 0.998. CONCLUSIONS: The radiation exposure to the staff involved in sentinel node (SN) biopsy for breast cancer using radioactive labelled tracers will be considerably below the permissible limits, even with high numbers of SN biopsy procedures. Pregnant staff members should participate in <100 SN operations.

Body Burden↗
PubMed2004

Patient-physician communication concerning participation in cancer chemotherapy trials.

Cancer patients demand a high level of involvement in decisions concerning treatment. Many patients are informed about experimental trials, and especially the first consultation may be crucial for the future communication and treatment process. Patients with nonresectable non-small-cell lung cancer or colorectal cancer informed about experimental chemotherapy completed a questionnaire on satisfaction with the communication process, general attitude towards experimental treatments, the substance of information, and personal contact with the physician following their first consultation in a medical oncology unit. Physicians completed a questionnaire on their perception of the patients' satisfaction. Among 68 physician-cancer patient pairs, 29 patients were informed on chemotherapy in randomised trials and 39 in nonrandomised studies. The general attitude towards experimental treatment was positive or very positive in 71% of patients. Information on the treatment was perceived as completely adequate in 93% of patients informed on randomised and in 67% informed on nonrandomised trials. Physicians underestimated the patients' satisfaction with the overall communication process, the personal contact, the patients' perceived sufficiency of the specific treatment information and their ability to decide on study entry. In conclusion, considerable differences were observed between patients informed about experimental chemotherapy in randomised and nonrandomised trials, both with respect to their perception of how adequate the information on the specific treatments were, and whether it was sufficient for decisions on study entry. This study type effect should be accounted for in future evaluations of communication and patient satisfaction. The data also support the fact that cancer patients have a desire for and ability to understand rather detailed and comprehensive treatment information.

Adult↗
PubMed2004

Sensitivity of the ultrasonic CARI technique for breast tumor detection using a FETD scheme.

The CARI (clinical amplitude/velocity reconstruction imaging) technique is a new ultrasonography for better detection of the breast cancer. The method uses the mammography-like positioning of the breast and a reference structure to assess the changes of sound velocity in the screened region. In this work, we present a first attempt to simulate the CARI technique using finite element time-domain (FETD) wave propagation. The CARI sensitivity to the size, shape and location of the tumors is investigated via the simulations on 2D and 3D breast models. Small lesions can be detectable under a suitable spatial resolution. 3D simulations agree with the quantitative results of the 2D case. Moreover, the FETD approximation is proving to be a simple, but robust tool in the CARI simulation.

Breast Neoplasms↗
PubMed2004

Fractional Laplacian time-space models for linear and nonlinear lossy media exhibiting arbitrary frequency power-law dependency.

Frequency-dependent attenuation typically obeys an empirical power law with an exponent ranging from 0 to 2. The standard time-domain partial differential equation models can describe merely two extreme cases of frequency-independent and frequency-squared dependent attenuations. The otherwise nonzero and nonsquare frequency dependency occurring in many cases of practical interest is thus often called the anomalous attenuation. In this study, a linear integro-differential equation wave model was developed for the anomalous attenuation by using the space-fractional Laplacian operation, and the strategy is then extended to the nonlinear Burgers equation. A new definition of the fractional Laplacian is also introduced which naturally includes the boundary conditions and has inherent regularization to ease the hypersingularity in the conventional fractional Laplacian. Under the Szabo's smallness approximation, where attenuation is assumed to be much smaller than the wave number, the linear model is found consistent with arbitrary frequency power-law dependency.

Acoustics↗
PubMed2003

Modified Szabo's wave equation models for lossy media obeying frequency power law.

Szabo's models of acoustic attenuation [Szabo, J. Acoust. Soc. Am. 96(1), 491-500 (1994)] comply well with the empirical frequency power law involving noninteger and odd-integer exponent coefficients while guaranteeing causality, but nevertheless encounter the troublesome issues of hypersingular improper integral and obscurity in implementing initial conditions. The purpose of this paper is to ease or remove these drawbacks of the Szabo's models via the Caputo fractional derivative concept. The positive time-fractional derivative is also introduced to include the positivity of the attenuation processes.

Journal Article↗
PubMed2002

Cerebral blood flow, oxidative metabolism and cerebrovascular carbon dioxide reactivity in patients with acute bacterial meningitis.

BACKGROUND: The optimal arterial carbon dioxide tension (P(a)CO(2)) in patients with acute bacterial meningitis (ABM) is unknown and controversial. The objective of this study was to measure global cerebral blood flow (CBF), cerebrovascular CO(2) reactivity (CO(2)R), and cerebral metabolic rates (CMR) of oxygen (O(2)), glucose (glu), and lactate (lac), in patients with ABM and compare the results to those obtained in healthy volunteers. METHODS: We studied 19 patients (17 of whom were sedated) with ABM and eight healthy volunteers (controls). CBF was measured during baseline ventilation and hyperventilation with single-photon emission computed tomography (SPECT) (14 patients) and/or the Kety-Schmidt technique (KS) (11 patients and all controls). In KS studies, CMR was measured by multiplying the arterial to jugular venous concentration difference (a-v D) by CBF. RESULTS: CBF did not differ significantly among groups, although a larger variation was seen in patients than in controls. CO(2)R was not significantly different among groups. At baseline, patients had significantly lower a-v DO(2), CMR(O(2)), CMR(glu), and CMR(lac) than controls. CMR(O(2)) did not change between hyperventilation compared to baseline ventilation, whereas CMR(glu) increased. CONCLUSION: In patients with acute bacterial meningitis, we found variable levels of CBF and cerebrovascular CO(2) reactivity, a low a-v DO(2), low cerebral metabolic rates of oxygen and glucose, and a cerebral lactate efflux. In these patients, a ventilation strategy guided by jugular bulb oximetry and/or repeated CBF measurements may be more optimal in terms of cerebral oxygenation than a strategy aiming at identical levels of P(a)CO(2) for all patients.

Adult↗
PubMed2002

Attitudes towards clinical research amongst participants and nonparticipants.

OBJECTIVES: To investigate attitudes to clinical research amongst cancer trial participants and nonparticipants, and to compare results with those from previous studies amongst participants in noncancer trials. DESIGN: Trial participating respondents were given three questionnaires during the clinical trials. Respondents amongst patients declining randomization answered a single questionnaire. SETTING: Participants and nonparticipants in randomized clinical cancer trials. SUBJECTS: Forty-one participants and 47 nonparticipants in cancer trials. RESULTS: Altruistic motives of physicians to conduct medical research were highly rated. Attitudes towards clinical research were positive in all groups, with nonparticipant respondents being the least positive. Eight to nine tenths found scientific testing necessary before general health service implementation. Trial participants were, as compared with nonparticipating respondents, more positive towards both participation of self and others. Both personal and altruistic motives for participation were highly rated. Primary reasons for nonparticipation were fear of 'the unknown' and/or unease with randomization. Only a minority felt a moral problem created by declining trial participation. Respondents amongst noncancer participants were more satisfied with the information given than both cancer participants and cancer nonparticipants. Negative experiences in cancer participants generally dealt with frustration related to seeing too many physicians at check-up appointments. CONCLUSION: Attitudes towards clinical research are generally positive even in cancer nonparticipants. Both personal and altruistic motives for participation were highly rated. A fear of 'the unknown' and resentments towards randomization were primary reasons to renounce participation. Seeing too many physicians at check-up appointments seems to be an important factor for negative experiences in cancer trial participants.

Adult↗
PubMed2002

New governance arrangements for research ethics committees: is facilitating research achieved at the cost of participants' interest.

This paper examines the UK's response to a recent European Clinical Trials Directive, namely the Department of Health, Central Office for Research Ethics Committee guidance, Governance Arrangements for NHS Research Ethics Committees. The revisions have been long awaited by researchers and research ethics committee members alike. They substantially reform the ethical review system in the UK. We examine the new arrangements and argue that though they go a long way toward addressing the uncertainty surrounding ethics committee function, the system favours the facilitation of research over the protection of the dignity and welfare of research participants.

Decision Making, Organizational↗
PubMed2001

[Reduced metabolism in cerebral cortex correlates with MRI changes and cognitive dysfunction in patients with disseminated sclerosis].

INTRODUCTION: Magnetic resonance imaging (MRI) lesion load is widely used in the clinical evaluation of patients with multiple sclerosis (MS), but little is known about the associated changes in cortical activation. For this purpose, we studied the association between the corticocerebral metabolic rate of glucose (CMRglc) and the MRI T2-weighted total lesion area (TLA). In addition, we investigated the correlation between cognitive and neurological disability and CMRglc. METHODS: Twenty-three patients with clinically definite MS underwent measurements of the CMRglc, TLA, motor-evoked potentials (MEP), and cognitive and neurological disability. CMRglc was calculated with positron emission tomography (PET) and 18-F-deoxyglucose (FDG) and compared to that of nine healthy controls. RESULTS: A reduction in CMRglc (p < 0.01) was found in cortical global and regional lobar measurements. Furthermore, regional CMRglc (rCMRglc) was reduced in the dorsolateral prefrontal cortex, orbitofrontal cortex, caudate, putamen, thalamus, and hippocampus. Global cortical CMRglc correlated with TLA (rho = -0.66; p = 0.001), and rCMRglc correlated with the regional lesion load in all cerebral lobes (p < or = 0.05). Global cortical CMRglc and cognitive disability were also correlated (rho = 0.58; p = 0.015), and stepwise regression analysis showed a significant association between rCMRglc of the right thalamus and cognitive performance, as well as the TLA. There was no correlation between CMRglc and neurological disability (expanded disability status scale [EDSS]) or MEP. CONCLUSION: Global and regional cortical CMRglc is significantly reduced in patients with MS compared to healthy controls. The reductions in CMRglc furthermore correlate with the TLA, as well as with cognitive dysfunction, which indicates that MRI white matter lesion burden has a deteriorating effect on corticocerebral neural function.

Adult↗
PubMed2001

Effect of recolonisation with "interfering" alpha streptococci on recurrences of acute and secretory otitis media in children: randomised placebo controlled trial.

OBJECTIVE: To study the effect of recolonisation with alpha streptococci with the ability to inhibit the growth of otopathogens ("interfering" activity) on the recurrence of acute otitis media in susceptible children and the effect on the frequency of secretory otitis media. DESIGN: Double blind, randomised, placebo controlled study. SETTING: Ear, nose, and throat clinic with three doctors. PARTICIPANTS: 130 children prone to otitis media aged between 6 months and 6 years, 108 of whom were eligible and followed for 3 months. MAIN OUTCOME MEASURES: Recurrence of otitis media during follow up and a normal tympanic membrane at the last valid visit. INTERVENTIONS: Children with no recurrences during the last month received phenoxymethylpenicillin (n=22), and those with a recurrence within 1 month received amoxicillin clavulanic acid (n=86), both twice daily for 10 days. These were followed by a streptococcal or placebo solution sprayed into the nose for a further 10 days. At day 60 the same spray was started for another 10 days. RESULTS: At 3 months 22 children (42%) given the streptococcal spray were healthy and had a normal tympanic membrane compared with 12 (22%) of those given placebo. This difference was shown separately for recurrences of both acute otitis media and secretory otitis media. CONCLUSIONS: Selected bacteria with the ability to inhibit the growth of common otopathogens can be used to protect against recurrent acute otitis media and secretory otitis media in children.

Aerosols↗
PubMed2001

Ethical issues in cardiopulmonary resuscitation.

If patients are to benefit from resuscitation, they must regain consciousness and their full faculties. In recent years, we have acquired important information about the natural history of neurological recovery from circulatory arrest. There are clinical tests that predict the outcome, both during ongoing cardiopulmonary resuscitation (CPR) and in the period after restoration of spontaneous circulation. The ability to predict neurological outcome at this stage offers a basis for certain ethical considerations, which are not exclusively centered on "do-not-attempt-resuscitation" (DNAR)- orders. Instead of being forced to make the decision that "I do not want CPR", the patient should be able to decide that "I want resuscitation to be discontinued, if you predict that I will not recover to a level of neurological function that is acceptable to me". Ideally, no competent patient should be given a DNAR-status without his or her consent. No CPR-attempt should be stopped, and no treatment decision for a patient recovering after CPR should be taken without knowing and assessing the available information. Good ethical decision-making requires reliable facts, which we now know are available.

Cardiopulmonary Resuscitation↗