Segmentation-free empirical beam hardening correction for CT

PURPOSE

The polychromatic nature of the x-ray beams and their effects on the reconstructed image are often disregarded during standard image reconstruction. This leads to cupping and beam hardening artifacts inside the reconstructed volume. To correct for a general cupping, methods like water precorrection exist. They correct the hardening of the spectrum during the penetration of the measured object only for the major tissue class. In contrast, more complex artifacts like streaks between dense objects need other techniques of correction. If using only the information of one single energy scan, there are two types of corrections. The first one is a physical approach. Thereby, artifacts can be reproduced and corrected within the original reconstruction by using assumptions in a polychromatic forward projector. These assumptions could be the used spectrum, the detector response, the physical attenuation and scatter properties of the intersected materials. A second method is an empirical approach, which does not rely on much prior knowledge. This so-called empirical beam hardening correction (EBHC) and the previously mentioned physical-based technique are both relying on a segmentation of the present tissues inside the patient. The difficulty thereby is that beam hardening by itself, scatter, and other effects, which diminish the image quality also disturb the correct tissue classification and thereby reduce the accuracy of the two known classes of correction techniques. The herein proposed method works similar to the empirical beam hardening correction but does not require a tissue segmentation and therefore shows improvements on image data, which are highly degraded by noise and artifacts. Furthermore, the new algorithm is designed in a way that no additional calibration or parameter fitting is needed.

METHODS

To overcome the segmentation of tissues, the authors propose a histogram deformation of their primary reconstructed CT image. This step is essential for the proposed algorithm to be segmentation-free (sf). This deformation leads to a nonlinear accentuation of higher CT-values. The original volume and the gray value deformed volume are monochromatically forward projected. The two projection sets are then monomially combined and reconstructed to generate sets of basis volumes which are used for correction. This is done by maximization of the image flatness due to adding additionally a weighted sum of these basis images. sfEBHC is evaluated on polychromatic simulations, phantom measurements, and patient data. The raw data sets were acquired by a dual source spiral CT scanner, a digital volume tomograph, and a dual source micro CT. Different phantom and patient data were used to illustrate the performance and wide range of usability of sfEBHC across different scanning scenarios. The artifact correction capabilities are compared to EBHC.

RESULTS

All investigated cases show equal or improved image quality compared to the standard EBHC approach. The artifact correction is capable of correcting beam hardening artifacts for different scan parameters and scan scenarios.

CONCLUSIONS

sfEBHC generates beam hardening-reduced images and is furthermore capable of dealing with images which are affected by high noise and strong artifacts. The algorithm can be used to recover structures which are hardly visible inside the beam hardening-affected regions.

Acetylated sialic acid residues and blood group antigens localise within the epithelium in microvillous atrophy indicating internal accumulation of the glycocalyx

BACKGROUND

Microvillous atrophy, a disorder of intractable diarrhoea in infancy, is characterised by the intestinal epithelial cell abnormalities of abnormal accumulation of periodic acid-Schiff (PAS) positive secretory granules within the apical cytoplasm and the presence of microvillous inclusions. The identity of the PAS positive material is not known, and the aim of this paper was to further investigate its composition.

METHODS

Formaldehyde fixed sections were stained with alcian blue/PAS to identify the acidic or neutral nature of the material, phenylhydrazine blocking was employed to stain specifically for sialic acid, and saponification determined the presence of sialic acid acetylation. The specificity of sialic acid staining was tested by digestion with mild sulphuric acid. Expression of blood group related antigens was tested immunochemically.

RESULTS

Alcian blue/PAS staining identified a closely apposed layer of acidic material on the otherwise neutral (PAS positive) brush border in controls. In microvillous atrophy, a triple layer was seen with an outer acidic layer, an unstained brush border region, and accumulation within the epithelium of a neutral glycosubstance that contained acetylated sialic acid. Blood group antigens were detected on the brush border, in mucus, and within goblet cells in controls. In microvillous atrophy they were additionally expressed within the apical cytoplasm of epithelial cells mirroring the PAS abnormality. Immuno electron microscopy localised expression to secretory granules.

CONCLUSIONS

A neutral, blood group antigen positive, glycosubstance that contains acetylated sialic acid accumulates in the epithelium in microvillous atrophy. Previous studies have demonstrated that the direct and indirect constitutive pathways are intact in this disorder and it is speculated that the abnormal staining pattern reflects accumulation of glycocalyx related material.

Results of 60 consecutive hepatectomies for pediatric living donor liver transplantation

Several technical improvements have been made to increase donor pool for pediatric liver transplantation, including reduced-size grafts, split-liver, and recently living donors. The objective of the present study is to report our single-center experience with 60 hepatectomies for living donor liver transplantation in pediatric recipients between June 2000 and December 2002. Donor workup consisted of a complete history and physical examination followed by laboratory test and liver function tests. Graft size was estimated using computed tomography scan or abdominal ultrasound. Liver biopsy was performed in all donors. Arteriogram was performed to evaluate hepatic arterial anatomy. All donors survived the procedure. Only seven patients experienced complications (10.2%), most of which were short term. We conclude that liver living donation for pediatric population is a safe procedure.

In vivo plasmid DNA electroporation generates exceptionally high levels of epitope-specific CD8+ T-cell responses

Based on observations that DBA/2 mice develop a highly specific response towards an HLA-Cw3-derived epitope, consisting entirely of CD8+CD62L-Vbeta10+ cells, we have established an in vivo mouse model for screening a variety of immunization approaches. Responder cells were readily detectable in small samples of the peripheral blood using three-color FACS analysis. This permitted multiple, sequential determination of CD8+ T-cell responses in living animals at a very high degree of precision. In vivo electroporation delivery of expression construct plasmids, outclassed the other approaches tested. Dominant, specific responses were induced already upon a single administration. Both the peak and the longevity of the response resembled those that are generated by the most active viral infections. The induced CTLs rejected epitope-bearing tumor cells in vivo and released interferon-gamma upon stimulation with the correct MHC::peptide combination in vitro. The potent in vivo response was not influenced by known modulators of the innate immune system, such as CpG DNA and LPS content. In vivo electroporation thus deserves consideration in the future in antitumor and antiviral immunization approaches, where CD8+ T cells play a predominant role.

Coronin is involved in uptake of Mycobacterium bovis BCG in human macrophages but not in phagosome maintenance

By applying density gradient electrophoresis (DGE) to human macrophages infected with Mycobacterium bovis BCG, we were able to separate three different bacterial fractions representing arrested phagosomes, phagolysosomes and mycobacterial clumps. After further purification of the phagosomal population, we found that isolated phagosomes containing live BCG were arrested in maturation as they exhibited only low amounts of the lysosomal glycoprotein LAMP-1 and processing of the lysosomal hydrolase cathepsin D was blocked. In addition, low amounts of MHC class I and class II molecules and the absence of HLA-DM suggest sequestration of mycobacterial phagosomes from antigen-processing pathways. We further investigated the involvement of the actin-binding protein coronin in intracellular survival of mycobacteria and showed that human coronin, as well as F-actin, were associated with early stages of mycobacterial phagocytosis but not with phagosome maintenance. Therefore, we conclude that the unique DGE migration pattern of arrested phagosomes is not as a result of retention of coronin, but that there are other proteins or lipids responsible for the block in maturation in human macrophages.

[Determination of breakpoints for veterinary medically relevant antibiotics for resistance assessment of veterinary pathogens]

This article describes the meaning of the term clinical breakpoint. This is followed by a discussion of the parameters that need to be considered when setting valid breakpoints for active substances in veterinary medicine; in doing so we closely follow equivalent regulations and guidelines on the establishment of breakpoints in human medicine. Along with pharmacokinetic data and the results of clinical efficacy tests, susceptibility data of relevant organisms play a key role in the establishment of breakpoints. Published breakpoints are currently only available for a few modern drugs in veterinary medicine.

[Ranking of 20 MHz sonography of malignant melanoma and pigmented lesions in routine diagnosis]

PURPOSE

Eleven dermatology clinics from all over Germany took part in our multicenter prospective study with the aim of evaluating 20 MHz sonography in the preoperative diagnosis of malignant melanomas and other pigmented skin tumours. It was to be assessed how effective sonographic measurement of thickness would compare to histology and the clinical palpation of tumour thickness and also the significance of differential diagnosis in sonography of malignant melanomas.

METHOD

The prospective multicenter study proceed as follows. To the end of August 1997 264 patients with a primary malignant melanoma and 417 patients with benign skin tumours were examined via 20 MHz sonography. Two different examiners estimated the clinical thickness of the tumour by palpation. The tumour was then excised and examined for postoperative correlation with the histology sections.

RESULTS

The final results showed good correlation between the histological and sonographic estimation of tumour thickness (r = 0.97). Estimation of tumour thickness by palpation showed no correlation with the histology (r = 0.59). Most of the benign (44%) and malignant tumours (38.7%) were spindle shaped. There was no significant difference between the benign and malignant tumour groups in relation to the sonographic presented shapes or echo signs. No different diagnosis could be made.

CONCLUSION

The technique of high frequency sonography in relation to preoperative diagnosis of malignant melanomas has high priority. In contrast to clinical estimation of tumour thickness, sonography provided a good correlation to histology. The effectiveness of sonography with regard to the valence of the skin tumours is limited and there is no possibility of differentiating between malignant and benign tumours from the morphological face value. Hence, there is a demand for developing a 150 MHz apparatus which will be able to supply evidence regarding the valence of skin tumours.

PEGylated DNA/transferrin-PEI complexes: reduced interaction with blood components, extended circulation in blood and potential for systemic gene delivery

We investigated the in vitro and in vivo properties of DNA/transferrin-polyethylenimine (800 kDa) complexes before and after covalent coupling of poly(ethylene glycol) (PEG). Upon incubation with plasma, the positively charged non-PEGylated DNA complexes form aggregates. Plasma proteins such as IgM, fibrinogen, fibronectin and complement C3 were found to bind to non-PEGylated DNA complexes. At DNA concentrations relevant for in vivo gene delivery a strong aggregation of erythrocytes was also observed. PEGylation of the complexes strongly reduces plasma protein binding and erythrocyte aggregation. Furthermore, PEGylated complex size was stabilized and had a reduced surface charge. Prolonged circulation in the blood of the PEGylated complexes was also observed when injected intravenously. In tumor bearing mice, application of non-PEGylated complexes through the tail vein resulted in reporter gene expression in tail and lung, but severe toxicity was observed in some mice. In contrast, PEGylated complexes mediated reporter gene transfer to the tumor without significant toxicity.

Polycation-based DNA complexes for tumor-targeted gene delivery in vivo

BACKGROUND

Efficient and target-specific in vivo gene delivery is a major challenge in gene therapy. Compared to cell culture application, in vivo gene delivery faces a variety of additional obstacles such as anatomical size constraints, interactions with biological fluids and extracellular matrix, and binding to a broad variety of non-target cell types.

METHODS

Polycation-based vectors, including adenovirus-enhanced transferrinfection (AVET) and transferrin-polyethylenimine (Tf-PEI), were tested for gene delivery into subcutaneously growing tumors after local and systemic application. DNA biodistribution and reporter gene expression was measured in the major organs and in the tumor.

RESULTS

Gene transfer after intratumoral application was 10-100 fold more efficient with Tf-PEI/DNA or AVET complexes in comparison to naked DNA. Targeted gene delivery into subcutaneously growing tumors after systemic application was achieved using electroneutral AVET complexes and sterically stabilized PEGylated Tf-PEI/DNA complexes, whereas application of positively charged polycation/DNA complexes resulted in predominant gene expression in the lungs and was associated by considerable toxicity.

CONCLUSION

For systemic application, the physical and colloidal parameters of the transfection complexes, such as particle size, stability, and surface charge, determine DNA biodistribution, toxicity, and transfection efficacy. By controlling these parameters, DNA biodistribution and gene expression can be targeted to different organs.

Polycation-based DNA complexes for tumor-targeted gene delivery in vivo

BACKGROUND

Efficient and target-specific in vivo gene delivery is a major challenge in gene therapy. Compared to cell culture application, in vivo gene delivery faces a variety of additional obstacles such as anatomical size constraints, interactions with biological fluids and extracellular matrix, and binding to a broad variety of non-target cell types.

METHODS

Polycation-based vectors, including adenovirus-enhanced transferrinfection (AVET) and transferrin-polyethylenimine (Tf-PEI), were tested for gene delivery into subcutaneously growing tumors after local and systemic application. DNA biodistribution and reporter gene expression was measured in the major organs and in the tumor.

RESULTS

Gene transfer after intratumoral application was 10-100 fold more efficient with Tf-PEI/DNA or AVET complexes in comparison to naked DNA. Targeted gene delivery into subcutaneously growing tumors after systemic application was achieved using electroneutral AVET complexes and sterically stabilized PEGylated Tf-PEI/DNA complexes, whereas application of positively charged polycation/DNA complexes resulted in predominant gene expression in the lungs and was associated by considerable toxicity.

CONCLUSION

For systemic application, the physical and colloidal parameters of the transfection complexes, such as particle size, stability, and surface charge, determine DNA biodistribution, toxicity, and transfection efficacy. By controlling these parameters, DNA biodistribution and gene expression can be targeted to different organs.

[Focal mucinosis of the eyelid]

PURPOSE

To present a case of focal mucinosis of the eyelid.

PATIENT

A male patient of Turkish origin born in 1982 desired therapy in 1995 for an asymptomatic tumour of the left medial upper lid which had been present probably since birth. The tumour was reduced with argon laser photocoagulation. Fourteen months later, in 1997, the tumour had enlarged so that a surgical excision was performed which histologically was interpreted as an unspecific inflammation. In 1998, the tumour had grown again at the original site, and there were additional three pedunculated tumours nearby at the lid margin. All tumours were surgically excised. Histology showed empty spaces in the upper dermis which contained some connective fibers, benign appearing fibroblasts and some leukocytes. The PAS-reaction and S100-immunohistology were negative while the lesion stained positive for alcianblue. The epidermis was intact. A diagnosis of a focal mucinosis of the eyelid was established.

CONCLUSIONS

Focal mucinosis of the eyelid seems to be exceedingly rare. It is probably caused by a local overproduction of hyaluronic acid of unknown etiology. Our patient demonstrates that focal mucinosis might perhaps be congenital. Moreover it may recur if excision is not complete. Focal mucinosis should be included in the differential diagnosis of long-lasting, asymptomatic lid tumours.

Suppression of major histocompatibility complex class I and class II gene expression in Listeria monocytogenes-infected murine macrophages

Macrophage cells play a central role during infection with Listeria monocytogenes by both providing a major habitat for bacterial multiplication and presenting bacterial antigens to the immune system. In this study, we investigated the influence of L. monocytogenes infection on the expression of MHC class I and class II genes in two murine macrophage cell lines. Steady-state levels of I-Abeta chain mRNA were decreased in both resting J774A.1 and P388D1 macrophages infected with L. monocytogenes whereas reduction of H-2K mRNA was only observed in P388D1 cells. In addition, L. monocytogenes suppressed induction of MHC class I and class II mRNAs in response to gamma-interferon as well as the maintenance of the induced state in activated P388D1 macrophages. Exposure to the non-pathogenic species L. innocua or a deletion mutant of L. monocytogenes, which lacks the lecithinase operon, did not cause a reduction in H-2K and I-Abeta mRNA levels nor suppress expression of Ia antigens. Inhibition of MHC gene expression may represent an important part of the cross-talk between L. monocytogenes and the macrophage that probably influences the efficiency of a T cell-mediated immune response and thus the outcome of a listerial infection.

Involvement of MAP-kinases and -phosphatases in uptake and intracellular replication of Listeria monocytogenes in J774 macrophage cells

In this study we show that protein tyrosine kinases and also protein tyrosine phosphatases are involved in the uptake of Listeria monocytogenes by J774 macrophages to a different extent than in the uptake of inert latex beads. In addition, protein tyrosine kinases are necessary for the intracellular growth and survival of L. monocytogenes. The expression of the MAP kinase phosphatase MKP-1, a protein tyrosine phosphatase, is induced upon infection, and phagocytosis of L. monocytogenes by J774 cells overexpressing the MKP-1 protein is reduced compared to control cells. The decreased phagocytosis of L. monocytogenes as a result of the MKP-1 overexpression in J774 macrophages suggests that the activation of the MAP kinase(s) ERK-1 and/or ERK-2 is an essential requirement for the uptake of L. monocytogenes by J774 macrophages.

Differences in virulence and in expression of PrfA and PrfA-regulated virulence genes of Listeria monocytogenes strains belonging to serogroup 4

Listeria monocytogenes isolates belonging to serogroup 4 (subtypes 4a, 4ab, 4b, 4c, 4d, and 4e) exhibit different levels of virulence in mice. Molecular studies indicate that in comparison with the control strain EGD (serotype 1/2a), these strains differ in the expression of the PrfA-regulated virulence genes, including prfA itself. Strains of serotypes 4c, 4d, 4e, and especially 4a show a low level of invasiveness in Caco-2 cells, which correlates in part with the low level of expression of the inlA gene. All serotypes reach the cytoplasm, at the latest, 2 h postinfection and become surrounded by polymerized actin within the next hour, but actin tail formation by serotype 4a, 4c, 4d, and 4e strains is drastically reduced. The actA genes in these serogroup 4 strains are expressed in minimum essential medium and within the phagocytic cell line J774. However, the amounts and (in part) the sizes of the ActA proteins in these strains differ under these conditions. The reduced actin tail formation by serotype 4a, 4c, 4d, and 4e strains may be due to the low level of in vivo expression of ActA. In addition, the loss of one repeat unit in the ActA proteins of serotype 4a and 4e strains may also contribute to the less efficient actin tail formation observed with these strains.

Lacrimal secretion of human epidermal growth factor in perforating keratoplasty

Human epidermal growth factor (hEGF) plays a key role in the regulation of corneal epithelial regeneration. As the lacrimal concentration of EGF is known to decrease following corneal injury, therapeutic application of exogenic EGF to support corneal wound healing is currently being investigated. To evaluate the role of topical EGF substitution in perforating keratoplasty, the lacrimal secretion of EGF was determined in 12 patients prior to keratoplasty and on the 1st and 7th days postoperatively using a newly developed modular immunofluorometric assay. EGF secretion and tear-flow rates in the tear samples of the keratoplasty patients were compared with those of 39 patients with corneal epithelial defects of other origin and those of 21 healthy controls. Levels of EGF secretion and tear flow reflectorily increased both in the post-operative samples of keratoplasty patients (secretion 0.77 +/- 0.56 pg/s, tear flow 18.7 +/- 14.9 microliter/min) and in the samples of patients with corneal epithelial defects (0.6 +/- 0.4 pg/s, 19.6 +/- 19.2 microliter/min) in comparison with preoperative values and healthy controls (0.3 +/- 0.2 pg/s, 4.0 +/- 5.4 microliter/min). Men showed higher average levels of basal and reflectory EGF secretion (0.4 and 0.8 pg/s), respectively than did women (0.25 and 0.55 pg/s, respectively). The results indicate a physiological feedback mechanism that reflectorily adjusts the lacrimal EGF secretion following corneal irritation. Topical therapy with recombinant EGF should therefore be restricted to patients with persistent corneal epithelial defects and proven deficiency of EGF secretion.

Detection and characterization by differential PCR of host eukaryotic cell genes differentially transcribed following uptake of intracellular bacteria

Host eukaryotic cell genes that are differentially transcribed after phagocytosis of various pathogenic and nonpathogenic bacterial cells were identified by a differential PCR (DPCR) system. This DPCR procedure favors detection and isolation of host genes affected at the transcriptional level by selecting for poly(A) tails but differs substantially from reverse transcription-PCR. Several unidentified macrophage gene fragments from genes that were either transcriptionally activated or downregulated following uptake of Listeria monocytogenes into J774 mouse macrophage cells were initially defined by this DPCR procedure. Because of the sensitivity of the DPCR technique, all of the genes exhibited less than a 10-fold difference in transcription compared with noninfected cells as measured by limiting-dilution PCR. One of the gene fragments has a very high level of homology with a mitogen-activated protein kinase phosphatase (MKP-1), whereas the other affected fragments showed no homologies to known gene sequences. In addition, one of the gene fragments (WS30-B2/1) was specifically downregulated after L. monocytogenes uptake and another gene was repressed by uptake of either Shigella flexneri or L. monocytogenes, while transcription of the genes represented by fragment WS13-B9/9, and to some extent MKP-1, was activated following general phagocytosis (i.e., following uptake of any species of bacterium tested). Further characterization of the affected genes was conducted by using mutants of L. monocytogenes. A hemolysin-negative mutant of L. monocytogenes failed to elicit transcriptional regulation of gene fragment WS10-B4/14 or WS30-B2/1, and it elicited only minimal regulation of MKP-1, suggesting that escape from the phagosome may be required to initiate these responses. Furthermore, mutants with mutations in mpl and actA, two genes whose gene products are involved in actin polymerization and intrahost spread, also did not induce regulation of WS10-B4/14. These results demonstrate that (i) DPCR can identify specific host cell genes which are differentially transcribed after infection with certain microorganisms and (ii) some of these genes may be new or may never before have been linked to interactions between hosts and pathogens.

Latent Marek's disease virus can be activated from its chromosomally integrated state in herpesvirus-transformed lymphoma cells

Marek's disease virus (MDV), a lymphotropic herpesvirus, induces T-cell lymphomas in chicken, its natural host. The lymphoma cells are latently infected with MDV but the viral contribution to the transformed phenotype is not understood. To investigate the virus-cell interaction, we focused on the status of MDV in the transformed cells. By the use of highly sensitive fluorescent in situ hybridization with metaphase chromosomes, we found (i) MDV DNA to be randomly integrated at multiple sites in the chromosomes of primary lymphoma cells from chicken tissues; (ii) extrachromosomal, circular MDV genomes were absent and linear virion DNA was usually not detectable in the latently infected lymphoma cells; (iii) the pattern of integration sites revealed the clonal origin of the tumour cells; which (iv) was retained in in vitro established cell lines derived from primary lymphomas; (v) activation of the lytic phase of MDV's life cycle occurred in vitro suggesting that MDV can escape from its integrated status by an unknown mechanism.

Liquid crystalline DNA in fowl adenovirus

Fowl adenovirus particles were studied using negative stain electron microscopy. Upon preparation, some particles collapsed and showed their internal structure. The DNA could be observed as thin parallel lines with a spacing of 25 A, very similar to images of the liquid crystalline DNA in bacteriophage heads and in herpes virus.

Identification of genomic regions of the herpesvirus of turkeys (HVT) with helper activity for avian adeno-associated virus (AAAV)

Herpesvirus of turkeys (HVT) is a potent helper for the defective parvovirus avian adeno-associated virus (AAAV). To study the helper mechanism at the molecular level, we established a complete cosmid library of HVT DNA in a set of seven overlapping clones and transiently cotransfected secondary chicken embryo fibroblast (CEF) cells with AAAV DNA and recombinant cosmids (cBL) (individual as well as in different combinations). Using an AAAV-specific indirect immunofluorescence assay, we identified four regions on the HVT genome, represented by cBL267, cBL27, cBL33, and cBL34, which express helper functions for AAAV. As demonstrated by infection studies with extracts from cotransfected CEF cells, cBL267 promotes productive AAAV growth, while the helper effect induced by cBL27, cBL33, and cBL34 is limited to the synthesis of noninfectious AAAV antigen. In view of the data presented, possible HVT-specific helper mechanisms for AAAV are discussed.

[EGF in therapy of corneal diseases. Principles and possible uses]

Numerous recent research results stress the importance of the epidermal growth factor (EGF) for the growth and differentiation of corneal tissues. EGF, a physiological ingredient in the tears, plays a predominant role in the regeneration of corneal epithelium. Furthermore, EGF has been shown to increase the proliferation and differentiation of corneal keratocytes and endothelial cells. Topically applied EGF significantly enhances both the re-epithelialization of denuded areas and the tear strength of stromal cicatrices. These results may lead to interesting pharmacological management procedures for numerous corneal disorders. Thus, the clinical feasibility of EGF therapy is currently the subject of intensive evaluation. A better understanding of its mode of action, both on the molecular and cellular level, and increasing knowledge of the pharmacokinetics, together with the development of suitable application media, may all make EGF an integral part of the next generation of ophthalmic drugs. This survey reviews basic molecular-pharmacological and biochemical findings on EGF and evaluates its possible value for therapeutical use.

[Heart involvement in progressive systemic sclerosis (generalized scleroderma)]

17 patients with progressive systemic sclerosis were examined for cardiac involvement using standard ECG, chest X-ray, 24-h Holter ECG, and echocardiography. The control groups consisted of 7 patients with mixed connective tissue disease, 10 patients with systemic lupus erythematosus, and 10 patients with rheumatoid arthritis. The results disclosed a cardiac involvement of 70% using all 4 methods, which is more than is reported in the literature. The data also show that all 4 methods are necessary to diagnose the cardiac involvement. Conduction and rhythm disorders especially are more frequent than in other collagen vascular diseases. The use of calcium channel blockers is discussed as a new therapeutic possibility.