Hypersensitivity reactions and contrast medium injection: are they always related?

Background

Hypersensitivity (allergic or non-allergic) reactions that occur after contrast medium (CM) injection are usually related to the CM. Recent studies, and case reports lack the analysis of alternate causes that could be also responsible in individual cases.

Patients and methods

We investigated the individual relevant factor/causative agent of adult patients with hypersensitivity reactions that occurred in radiological units during CM-enhanced procedures (CT, angiography, urography, or MR-examinations). Both immediate and non-immediate (delayed) reactions were included. To find out the relevant agent a detailed patients’ history was carefully analyzed. In addition, the records were retrospectively reviewed, and if indicated and possible laboratory (e.g. basophil activation test) and skin tests (e.g. prick) and/or provocations with CM-injections under routine conditions were performed.

Results

38 patients (men n = 21) suspected for CM-hypersensitivity reactions were identified. These reactions were in most cases mild (n = 21), moderate reactions occurred in 13 cases, and four patients had severe reactions. In 28 patients the reactions were induced by the CM (iodinated CM in 25 cases). Four patients had reactions that were not CM-related (latex allergy, adenosine reaction, vasovagal reaction, unknown cause) and in six cases the reaction was partly CM-related (immunological activation was present due to the patients’ diseases).

Conclusion

Our data support the hypothesis that in CM-enhanced procedures not only contrast materials but also a broad range of other factors may also induce hypersensitivity reactions. Therefore, the number of CM-induced hypersensitivity is smaller than initially suspected. The knowledge of the cause of a reaction is essential to effectively prevent its recurrence and to improve safety aspects in patients undergoing CM-injection. Larger trials should be performed to more specifically assess alternate causes in patients who acquire hypersensitivity reactions in CM-enhanced diagnostic procedures.     

The immunological synapse controls local and global calcium signals in T lymphocytes

Summary:  Cell polarization is a key feature of T-cell function. The immunological synapse (IS) between T cells and antigen-presenting cells is a beautiful example of how polarization of cells is used to guide cell function. Receptors, signal transducers, the cytoskeleton, and organelles are enriched at or depleted from the IS after its formation, and in many cases these re-localizations have already been linked with certain T-cell functions. One key step for T-cell activation is a rise in the cytoplasmic calcium concentration. Whereas it is undisputed that the IS initiates and controls calcium signals in T cells, very little is known about the role of T-cell polarization for calcium signals and calcium-dependent signal transduction. We briefly summarize the basic commonly agreed principles of IS-dependent calcium signal generation but then focus on the less well understood influence of polarization on calcium signals. The discussion of the role of polarization for calcium signals leads to a model how the IS controls local and global calcium signals and calcium-dependent T-cell functions. We develop a theoretical formalism based on existing spatiotemporal calcium dynamic simulations to better understand the model in the future and allow further predictions which can be tested by fast, high resolution live-cell microscopy.     

Cervical range of movement in relation to neck dimension

The authors investigated the effect of neck dimension upon cervical range of motion. Data relating to 100 healthy subjects, aged between 20 and 40 years, were recorded with respect to age, gender and range of motion in three planes. Additionally, two widely used methods of measuring neck motion, chin-sternal distance and uniplanar goniometer, were assessed against a validated measurement tool, the ‘CROM goniometer’. Using multiple linear regression analysis it was determined that sagittal flexion (P = 0.002) and lateral rotation (P < 0.0001) were most closely related to neck circumference alone whereas lateral flexion (P < 0.0001) was most closely related to a ratio of circumference and length of neck. Hence, assessing cervical range of motion as outcome variable or as a measure at posttreatment follow-up, neck circumference was shown to be one of the factors influencing total neck motion, particularly sagittal flexion and lateral tilt. Comparison of cervical range of motion assessed with a validated measurement tool, the CROM goniometer, with results of both frequently applied clinician’s instruments, the uniplanar goniometer and measurement of chin-sternal distance, showed low reliability with the latter techniques, and motion values measured with these techniques should be interpreted with caution if using them for comparison of cervical range of motion of alike groups. We demonstrated that neck dimension should be incorporated into cervical functional outcome assessment and one should be wary about recorded values for neck motion from non-validated measurement tools.     

Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification

Losses of biodiversity and ecosystem functioning due to rainforest destruction and agricultural intensification are prime concerns for science and society alike. Potentially, ecosystems show nonlinear responses to land-use intensification that would open management options with limited ecological losses but satisfying economic gains. However, multidisciplinary studies to quantify ecological losses and socioeconomic tradeoffs under different management options are rare. Here, we evaluate opposing land use strategies in cacao agroforestry in Sulawesi, Indonesia, by using data on species richness of nine plant and animal taxa, six related ecosystem functions, and on socioeconomic drivers of agroforestry expansion. Expansion of cacao cultivation by 230% in the last two decades was triggered not only by economic market mechanisms, but also by rarely considered cultural factors. Transformation from near-primary forest to agroforestry had little effect on overall species richness, but reduced plant biomass and carbon storage by approximately 75% and species richness of forest-using species by approximately 60%. In contrast, increased land use intensity in cacao agroforestry, coupled with a reduction in shade tree cover from 80% to 40%, caused only minor quantitative changes in biodiversity and maintained high levels of ecosystem functioning while doubling farmers' net income. However, unshaded systems further increased income by approximately 40%, implying that current economic incentives and cultural preferences for new intensification practices put shaded systems at risk. We conclude that low-shade agroforestry provides the best available compromise between economic forces and ecological needs. Certification schemes for shade-grown crops may provide a market-based mechanism to slow down current intensification trends.