C5a receptors are detectable on mast cells in normal human skin and in psoriatic plaques but not in weal and flare reactions or in urticaria pigmentosa by immunohistochemistry

The expression of the receptor for the anaphylatoxin C5a on mast cells was studied with three monoclonal antibodies directed to the N-terminal domain of the C5a receptor. Human skin was investigated by immunohistology applied to sequential 2 μm sections of acrylate-embedded tissues. All anti-C5a receptor antibodies stained c-kit ⁺ or tryptase ⁺ cells which were metachromatic after toluidine blue staining in normal human skin. The binding of anti-C5a receptor antibodies was inhibitable by a peptide representing the first 31 amino acids of the C5a receptor. A similar expression of C5a receptors was found on mast cells in chronic psoriatic plaques. However, C5a receptors were not detectable on mast cells in weal and flare reactions or in lesional skin of urticaria pigmentosa. These findings suggest that (1) anti-C5a receptor antibodies directed to the N-terminal domain of the receptor are suitable tools for the identification of mast cells in acrylate-embedded sections of human skin, (2) mast cell activation in weal and flare reactions results in C5a receptor downregulation or receptor blockade and (3) mast cells in urticaria pigmentosa lack a typical marker of normal human skin mast cells. Received: 29 November 1995     

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Computer-assisted screw insertion into the first sacral vertebra using a three-dimensional image intensifier: results of a controlled experimental investigation

Currently there are few data available regarding the application and efficacy of computer-assisted procedures in the sacral spine. In order to optimize and standardize this procedure, a controlled experimental investigation has been performed. The aim of the study is to systematically assess the efficacy of a novel three-dimensional image intensifier used for navigated transiliac screw insertion into the first sacral vertebra. Screws were inserted iliosacrally into the first sacral vertebra of preserved human cadaver specimens. The instrument navigated procedure was performed with the Siremobil Iso-C^3D (Siemens Medical Solutions) and the Navigation System by Stryker. The accuracy and quality of the imaging procedure as well as the fluoroscopic exposure times were measured. These results were compared to three control groups (CT-based navigation, C-arm navigation, and fluoroscopic guidance). In each group a total amount of 20 screws was implanted. Screw position was postoperatively assessed by Iso-C^3D or CT-scan. The navigated procedure using the Iso-C^3D provided good feasibility characteristics without requiring a specific matching process. It revealed the shortest procedure time of all navigated procedures and significantly decreased fluoroscopic time compared to C-arm navigation and fluoroscopic guidance. Furthermore, Iso-C^3D navigation showed no screw malposition and was in this regard superior to C-arm navigated and fluoroscopic guided procedures. The quality of imaging was sufficient for accurate placement, but did not share the high-resolution level of CT-based navigation. These findings indicate that application of the Iso-C^3D for navigated transiliac screw insertion into S1 can be recommended as a feasible and safe technique, enabling the surgeon to reduce procedure and fluoroscopic time. Further progress in improving the quality of the Iso-C^3D image should be attempted.     

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Folgen der okkulten Insuffizienzfraktur des Os sacrum

Low back pain disorders of the elderly can potentially be caused by sacral insufficiency fractures due to osteoporosis, radiation necrosis or seldom malignant processes. In our institution an increasing numbers of patients suffering from osteoporotic sacral insufficiency fractures could recently be observed. In a case report study clinical symptoms, diagnostic procedures as well as therapeutic options are discussed.     

New sources of retinoic acid synthesis revealed by live imaging of an Aldh1a2-GFP reporter fusion protein throughout zebrafish development

Background: Regulation of synthesis and turnover of retinoic acid (RA) is an important mechanism that controls the activity of RA signaling during vertebrate development. During embryonic patterning, the dynamic expression patterns of the aldh1a2 gene, which encodes a retinaldehyde dehydrogenase, provide the major source of RA, whereas the only other retinaldehyde dehydrogenase in teleosts, aldh1a3, is expressed later and locally restricted. Aldh1a2‐mediated RA synthesis has been shown to also regulate adult cell fates, such as during heart and fin regeneration. However, only very few other sites of postembryonic RA synthesis in vertebrates are known. We generated transgenic lines in zebrafish by BAC recombineering that express a fusion protein of Aldh1a2 and green fluorescent protein (GFP) under the control of endogenous aldh1a2 regulatory sequences (aldh1a2:gfp). Results: aldh1a2:gfp reports the complete endogenous expression pattern in embryos and rescues embryonic lethality in aldh1a2 mutants. We identify novel postembryonic sources of RA synthesis, including lateral line support cells, in kidney‐derived organs that regulate calcium homeostasis, and in perichordal cells during vertebral development. Conclusions: The novel aldh1a2 reporter line is driven by the complete set of regulatory sequences required for zebrafish development, reports novel sources of RA synthesis, and identifies the source of RA that promotes vertebral ossification. Developmental Dynamics 241:1205–1216, 2012. © 2012 Wiley Periodicals, Inc.     

Intraindividual comparison of gadolinium- and iodine-enhanced 64-slice multidetector CT pulmonary angiography for the detection of pulmonary embolism in a porcine model

This study is an evaluation of the diagnostic accuracy of gadolinium-enhanced computed tomography pulmonary angiography (CTPA) for the detection of pulmonary embolism (PE) in comparison with iodine-enhanced CTPA. PE was induced in five anesthetized pigs by administration of blood clots through an 11-F catheter inside the jugular vein. Animals underwent CTPA in breathhold with i.v. bolus injection of 50 ml gadopentetate dimeglumine (0.4 mmol/kg, 4 ml/s). Subsequently, CTPA was performed using the same imaging parameters but under administration of 70 ml nonionic iodinated contrast material (400 mg/ml, 4 ml/s). All images were reconstructed with 1 mm slice thickness. A consensus readout of the iodium-enhanced CTPAs by both radiologists served as reference standard. Gadolinium-enhanced CTPAs were evaluated independently by two experienced radiologists, and differences in detection rate between both contrast agents were assessed on a per embolus basis using the Wilcoxon signed-rank test. Interobserver agreement was determined by calculation of қ values. PE was diagnosed independently by both readers in all five pigs by the use of gadolinium-enhanced CTPA. Out of 60 pulmonary emboli detected in the iodine-enhanced scans, 47 (78.3%; reader 1) and 44 (62.8%; reader 2) emboli were detected by the use of gadolinium. All 13 (100%) emboli in lobar arteries (by both readers) and 26 (reader 1) and 25 (reader 2) out of 27 emboli (96.3% and 92.6%) in segmental arteries were detected by the use of the gadolinium-enhanced CTPA. In subsegmental arteries, only 8 (40%; reader 1) and 6 (30%; reader 2) out of 20 emboli were detected by the gadolinium-enhanced CTPA. By comparing both scans on a per vessel basis (Wilcoxon test), Gd-enhanced CTPA was significantly inferior in emboli detection on subsegmental level (P < 0.0001). The interobserver agreement was excellent on lobar and segmental level (қ = 1.0 and 0.93, respectively), whereas readers only reached moderate agreement for PE evaluation on subsegmental level (қ = 0.56). Compared to conventional CTPA with iodinated contrast media, gadolinium-based contrast agents achieve an equivalent diagnostic accuracy in detection of PE down to segmental level. Gadolinium-enhanced CTPA may be considered as an alternative for the diagnostic workup of acute pulmonary embolism in patients with contraindications to iodinated contrast agents.