Noninvasive determination of genome size and ploidy level in fishes by flow cytometry: detection of triploid Poecilia formosa

BACKGROUND

In order to understand the evolutionary significance of single triploids among the mostly diploid Poecilia formosa we have developed a simple, noninvasive technique for DNA content and ploidy determination.

METHODS

From dorsal fin clips of 14 different fish species single cell suspensions were obtained by chopping the material in 2.1% citric acid/0.5% Tween20, passing it through a 0. 6-gauge needle and incubating it for 20 min at room temperature (RT) with gentle agitation. After overnight fixation in 70% ethanol, the cells were treated with 1ml 0.5% pepsin/0.1 M HCl for 15 min at RT before adding DAPI to a final volume of 2 ml. The cells were stained for 1-3 h and then analyzed by flow cytometry.

RESULTS

We obtained good measurements with CVs ranging from 1.23% to 3.36%. The poeciliid species measured contain from 1.6 to 2.0 pg/nucleus, Oryzias latipes (Medaka) exhibits a nuclear DNA content of 2.2 pg, Danio rerio (zebrafish) 4.6 pg, Tetraodon fluviatilis (freshwater fugu) 0.70 pg. All values except zebrafish are in good agreement with the literature.

CONCLUSIONS

The identification of living specimens of different ploidy for breeding experiments, behavioral studies and tissue transplantations is now made possible. With slight modifications the method can be extended to a field technique, providing therefore a useful tool for a variety of researchers.

High sensitivity detection of JC-virus DNA in postmortem brain tissue by in situ PCR

Opportunistic infection of the central nervous system by human polyomavirus JC can cause a devastating disease, progressive multifocal leukoencephalopathy (PML). To gain new neuropathological insights into JC-virus (JCV) infection patterns in PML at the light microscopic level, the highly sensitive indirect in situ polymerase chain reaction (in situ PCR) was employed in up to 15-year old formalin-fixed and paraffin-embedded postmortem brain tissue derived from nine AIDS patients with PML. In situ PCR, in which target DNA is amplified intracellularly and detected by a specific labelled probe in morphologically intact tissue, was compared with conventional in situ hybridization (ISH). Validity was ensured by the inclusion of 13 controls. JCV detection with in situ PCR proved to be highly sensitive since in all nine brain samples the number of positive cells exceeded the ISH results by 2-3-fold. Whereas by routine staining the brain tissue of each individual patient showed regions with severe, mild or no involvement by PML, improved detection of JCV DNA by in situ PCR allowed a regrading into five different degrees of JCV infection. Significant myelin staining was observed, suggesting that cell-to-cell contact may not be the only means of virus spread but that new cells could also be infected by virus released after cell lysis. Furthermore, using in situ PCR hitherto unreported intracellular distribution patterns of JCV DNA in oligodendro- and astrocytes were observed by light microscopy.

Homozygotes for FRA16B are normal

Homozygotes for the rare folate-sensitive autosomal fragile sites have never been recorded. Two non-folate-sensitive rare fragile sites (FRA10B and FRA17A) have been previously recorded in normal individuals. We document two unrelated normal individuals who are homozygotes for the rare fragile site FRA16B and record the patterns of induction of this fragile site with berenil. The existence of normal homozygotes for FRA16B suggests that this fragile site is not within a gene essential for normal development.

Identification and characterization of a mouse homolog to yeast Cdc6p

Periodic expression of the Cdc6 protein is essential for the entry of budding yeast cells into S phase, and also for participating in checkpoint controls that ensure that DNA replication is completed before mitosis is initiated. We have identified a mouse protein closely related to Cdc6p (MmCdc6p) as well as to its human and Xenopus homologs. The gene coding for MmCdc6p (Cdc6) is located at band D on murine chromosome 11. Analysis of its genomic region revealed that the 13-kb Cdc6 gene is divided into 12 exons by 11 introns. MmCdc6p has putative cyclin-dependent phosphorylation sites, a destruction box, nuclear localization signals, a nucleotide triphosphate-binding motif, and a potential leucine zipper. None of these consensus motifs except the leucine-zipper and the destruction box overlaps an intron. Expression of MmCdc6 mRNA and protein is suppressed in mouse NIH3T3 fibroblasts made quiescent by serum starvation. Upon replenishment of the medium, transcript and protein levels increase during progression through G(1), peaking as cells enter S phase. MmCdc6p is phosphorylated in vitro by cdk1/cyclin B, cdk4/cyclin D, cdk2/cyclin E, and cdk2/cyclin A, respectively at serine-residues. In vivo however, phosphorylation of MmCdc6p is carried out by cdk2/cyclin A at serine-residues exclusively. Conservation of structures among members of the Cdc6-related proteins suggests that these proteins play a key role in the regulation of DNA replication during the cell cycle in all eukaryotes. These results strongly suggest, that Cdc6p plays an important role in cell cycle regulation and replication licensing.

Programmed cell death in castor bean endosperm is associated with the accumulation and release of a cysteine endopeptidase from ricinosomes

The cells of the endosperm of castor bean seeds (Ricinus communis) undergo programmed cell death during germination, after their oil and protein reserves have been mobilized. Nuclear DNA fragmentation first was observed at day 3 in the endosperm cells immediately adjacent to the cotyledons and progressed across to the outermost cell layers by day 5. We also detected the accumulation of small organelles known as ricinosomes, by using an antibody against a cysteine endoprotease. By the time the nuclear DNA was susceptible to heavy label by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling, the ricinosomes had released into the cytoplasm their content of cysteine endoprotease, which became activated because of the cleavage of its propeptide. The cysteine endoprotease is distinguished by a C-terminal KDEL sequence, although it is not retained in the lumen of the endoplasmic reticulum and is a marker for ricinosomes. Homologous proteases are found in the senescing tissues of other plants, including the petals of the daylily. Ricinosomes were identified in this tissue by electron microscopy and immunocytochemistry. It seems that ricinosomes are not unique to Ricinus and play an important role in the degradation of plant cell contents during programmed cell death.

Developmental stage- and germ cell-regulated expression of a calcium-binding protein mRNA in mouse Sertoli cells

There is considerable evidence that germ cells, mainly spermatocytes and spermatids, contribute to the regulation of Sertoli cell activity. We developed an in vitro system to investigate the genes involved in Sertoli cell-germ cell interaction in the mouse by using the differential mRNA display technique. One of the isolated differentially expressed genes, named calgizzarin, belongs to the family of S100 calcium-binding proteins and shows a decreased expression in Sertoli cell-germ cell cocultures compared to cultured Sertoli cells alone. Calgizzarin is expressed in all adult tissues examined, including testis and ovary; however, a high mRNA level for calgizzarin in mouse testis is maintained until day 15 of postnatal development and then declines dramatically, whereas the expression pattern in the ovary remains constantly high. Furthermore, Northern blot studies on testicular RNA from different mouse mutants with defects in spermatogenesis revealed that high levels of calgizzarin transcripts can only be detected in testes of mouse mutants with either no germ cells or primary spermatocytes, but only weak signals for calgizzarin are observed in testes of mutants containing spermatids. In addition, using both RT-PCR analysis and whole-mount in situ hybridization on dissected gonads it was demonstrated that mouse calgizzarin expression starts at 13.5 dpc in the prenatal male gonad and at 16.5 dpc in the embryonic ovary, respectively. The mouse calgizzarin gene was localized on mouse chromosome 5, region E-F. Taken together, our results indicate that calgizzarin expression could be repressed by factors originated from pachytene spermatocytes and/or spermatids.

A double-blind randomized-phase II trial comparing immunization with antiidiotype goat antibody vaccine SCV 106 versus unspecific goat antibodies in patients with metastatic colorectal cancer

This article reports on the first double-blind randomized clinical study with an antiidiotype antibody vaccine in patients with metastatic colorectal carcinoma. The study was performed to determine immunological parameters, efficacy, and tolerability of the vaccine. Forty-two patients with metastatic colorectal cancer were randomly assigned to multiple immunizations with goat IgG antiidiotype vaccine SCV 106 (n = 21) or unspecific goat IgG as controls (n = 21). The antiidiotype vaccine mimicked the 17-1A glycoprotein antigen associated with colorectal cancer. Of the 42 patients entered, 39 were evaluable for efficacy (SCV 106, n = 18; controls, n = 21). Twenty-nine patients raised antibodies to the vaccines (immunological responders, SCV 106, n = 12; controls, n = 17). Only in the SCV 106 group was a significant increase (p = 0.002) of titers with specificity of antitumor antibody 17-1A found. According to the International Union Against Cancer (UICC) criteria no tumor response was observed. However, in the SCV 106 group the relative increase of carcinoembryonic antigen (CEA) levels between entry and observed disease progression was lower (p = 0.03) and disease progression was determined less frequently by development of new metastases (p = 0.001). On an intention-to-treat basis, the survival time difference between the two groups was not significant. Comparison of immunological responders in both groups revealed a significant survival advantage of the SCV 106-treated patients compared with controls (mean 67 versus 39 weeks; p = 0.01). Immunizations were well tolerated. Vaccination of immunologically responding metastatic colorectal carcinoma patients with SCV 106 leads to slowed disease progression and tumor dissemination and significantly prolongs survival time.

Human eukaryotic initiation factor EIF2C1 gene: cDNA sequence, genomic organization, localization to chromosomal bands 1p34-p35, and expression

We report the cloning and characterization of the human eukaryotic protein translation initiation factor EIF2C1 gene. The human EIF2C1 gene consists of 19 exons and 18 introns that span a region of almost 50 kb. It is located on the short arm of chromosome 1 in the region 1p34-p35. This genomic region is frequently lost in human cancers such as Wilms tumors, neuroblastoma, and carcinomas of the breast, liver, and colon. The human EIF2C1 gene is ubiquitously expressed at low to medium levels. Differential polyadenylation and splicing result in a complex transcriptional pattern. The cDNA sequence is 7478 bp long and contains an extremely large 3' untranslated region of 4799 bp with multiple, short repeated segments composed of mono-, tri-, or quattronucleotides interspersed throughout. The human EIF2C1 gene belongs to a multigene family in human. It is highly conserved during evolution, sharing about 90% identity with rabbit eIF2C and 70% identity with plant AGO1 at the amino acid level. These facts suggest that human EIF2C1 might play an important physiological role.

Identification, characterization and chromosomal localization of the cognate human and murine DBF4 genes

The kinase Dbf4p/Cdc7p is required for the G1/S phase transition during the cell cycle and plays a direct role in the activation of individual origins of replication in Saccharomyces cerevisiae. Here, we report the identification and characterization of mouse and human cDNAs whose products are related in sequence to Saccharomyces cerevisiae DBF4 cDNA. Both mammalian Dbf4 proteins contain a putative site for phosphorylation by CDK, PEST protease cleavage sites, nuclear localization signals and a short-looped zinc finger-like domain. Transcription of MmDBF4 is suppressed in mouse NIH3T3 fibroblasts made quiescent by serum starvation. Upon replenishment of the medium, transcript levels increase during progression through G1, peaking as cells enter S phase. MmDbf4p interacts physically with Cdc7p and Mcm2p in vivo. Using fluorescence in situ hybridization (FISH), the human DBF4 gene was localized to chromosome 7 (q21.3), whereas FISH mapped the murine counterpart to band A2 on chromosome 5. The results of chromosome mapping indicate that in both mouse and human the gene is present as a single copy. The structural conservation between Dbf4-related proteins suggests that these proteins play a key role in the regulation of DNA replication during the cell cycle in all eukaryotes.

Virtual MR arthroscopy: new insights into joint morphology

Evaluation of the feasibility of virtual magnetic resonance (MR) arthroscopy was performed on 10 patients referred for MR arthrography of the shoulder, the elbow, or the knee. A fast spoiled contrast-enhanced three-dimensional gradient-echo sequence was combined with image postprocessing to render arthroscopic views. Virtual MR arthroscopy was successfully demonstrated in all 10 joints. Determination of added diagnostic benefit will require further study.

A novel testicular haploid expressed gene (THEG) involved in mouse spermatid-sertoli cell interaction

The successful production of male gametes requires extensive and precise interactions between germ cells and surrounding testicular somatic cells. We have made use of the mRNA differential display technique to isolate genes involved in germ cell-Sertoli cell interaction. We have identified five differential cDNA bands by comparing RNA from Sertoli cells, spermatids and spermatid-Sertoli cell cocultures. One of the isolated cDNA fragments detected a 1. 4-kilobase (kb) testis- and spermatid-specific transcript (designated as THEG: testicular haploid expressed gene). Northern blot analysis on RNA from spermatids and spermatid-Sertoli cell cocultures demonstrated that Sertoli cells are required for the continued expression of THEG in spermatids. We found two alternatively spliced transcripts for the THEG gene with 1437 base pairs (bp) and 1375 bp by using reverse transcription-polymerase chain reaction. The two open reading frames of 376 amino acids and 181 amino acids coded for putative nuclear proteins. The gene is approximately 10 kb pairs in size, contains 8 exons, and was mapped on mouse chromosome 10 to region B5-C1. Comparison of the two cDNA sequences with the genomic sequence indicated that the smaller transcript lacks exon 4. The differential gene expression of THEG in spermatid-Sertoli cell coculture supports the relevance of germ cell-Sertoli cell interaction for gene regulation during spermatogenesis.

Neointimal growth can be influenced by local adventitial gene manipulation via a needle injection catheter

Revascularization by percutaneous transluminal coronary angioplasty is limited in the long-term by restenosis, which is luminal renarrowing in the first 6 months after the procedure. Smooth muscle cell proliferation is thought to be an important factor in restenosis; this leads to neointima formation and arterial lumen narrowing. Local therapy delivered perivascularly may have an effect on events in the neointima and reduce restenosis. The effect of delivering expression vector plasmids for senescent cell-derived inhibitor SDI-1, which regulates cell proliferation, and its antisense, into the perivascular tissue of injured arteries was investigated in a porcine arterial injury model using a needle injection catheter. Transfection efficiency, biological effect and plasmid dissemination were evaluated in arterial and organ tissue sections between 2 days and 4 months. A limited number of adventitial, medial and neointimal cells were transfected up to 4 months. sdi gene transfer did not result in a change in neointima. Transfer of antisense sdi resulted in an increase in neointima after 3 weeks. No DNA plasmid was detected in control tissues. Liposomally-mediated adventitial local gene delivery is feasible and safe using the needle injection catheter in a porcine model. A limited number of cells was transfected, with expression of transfected genes up to 4 months after delivery. A transient biological effect with increased neointima was observed after delivery of the antisense sdi gene.

Molecular genetic alterations in radiation-induced astrocytomas

Astrocytic tumors occasionally arise in the central nervous system following radiotherapy. It is not clear if these gliomas represent a unique molecular genetic subset. We identified nine cases in which an astrocytoma arose within ports of previous radiation therapy, with total doses ranging from 2400 to 5500 cGy. Irradiated primary lesions included craniopharyngioma, pituitary adenoma, Hodgkin's lymphoma, ependymoma, pineal neoplasm, rhabdomyosarcoma, and three cases of lymphoblastic malignancies. Patients ranged from 9 to 60 years of age and developed secondary tumors 5 to 23 years after radiotherapy. The 9 postradiation neoplasms presented as either anaplastic astrocytoma (3 cases) or glioblastoma multiforme (6 cases). Two of the latter contained malignant mesenchymal components. We performed DNA sequence analysis, differential polymerase chain reaction (PCR), and quantitative PCR on DNA from formalin-fixed, paraffin-embedded tumors to evaluate possible alterations of p53, PTEN, K-ras, EGFR, MTAP, and p16 (MTS1/CDKN2) genes. By quantitative PCR, we found EGFR gene amplification in 2 of 8 tumors. One of these demonstrated strong immunoreactivity for EGFR. Quantitative PCR showed chromosome 9p deletions including p16 tumor suppressor gene (2 of 7 tumors) and MTAP gene (3 of 7). Five of 9 tumors demonstrated diffuse nuclear immunoreactivity for p53 protein. Sequencing of the p53 gene in these 9 cases revealed a mutation in only one of these cases, a G-to-A substitution in codon 285 (exon 8). Somewhat unexpectedly, no mutations were identified in PTEN, a commonly altered tumor suppressor gene in de novo glioblastoma multiformes. Unlike some radiation-induced tumors, no activating point mutations of the K-ras proto-oncogene or base pair deletions of tumor suppressor genes were noted. These radiation-induced tumors are distinctive in their high histological grade at clinical presentation. The spectrum of molecular genetic alterations appears to be similar to that described in spontaneous high grade astrocytomas, especially those of the de novo type.

Heterogeneity of HLA-G gene transcription and protein expression in malignant melanoma biopsies

Nonclassical MHC class I HLA-G antigen expression is tissue specific and is thought to play a role in tolerance of the semiallogeneic fetus by the maternal immune system. Ectopic expression of HLA-G by tumor cells provides them with an additional mechanism of escape from immunosurveillance by host cytotoxic effector mechanisms. The aim of this study was to assess the expression of nonclassical HLA-G antigens in ex vivo human melanoma biopsies. HLA-G mRNA levels corresponding to both membrane-bound and soluble protein isoforms were analyzed in tumor specimens obtained from primary or metastatic melanomas of 23 patients. High levels of HLA-G transcription were detected in tumor specimens in 5 of 23 patients and found to be comparable in both lymph node and skin metastases. HLA-G mRNA transcript levels at tumor sites in 18 of these patients were compared with those in samples of their own healthy skin and were higher in the tumor tissue in 12 patients. Differential expression of mRNA transcripts corresponding to soluble and membrane-bound HLA-G was also observed in some tumor biopsies. HLA-G protein expression was detected in tumors that exhibited high levels of HLA-G transcription by immunofluorescence of frozen sections and Western blot analysis of both tumor and healthy skin biopsies, using anti-HLA-G-specific monoclonal antibodies. This work provides evidence that HLA-G gene transcription and protein expression can be up-regulated ex vivo in melanoma. Our finding that several of the tumors studied expressed high levels of HLA-G provides additional clues as to how a tumor can be selected in vivo to escape from cytotoxic antitumor responses, constituting a new parameter to be considered in the design of therapeutic approaches aimed at enhancing antitumor immune responses.

[Recording of multiple sclerosis in Swiss cause of death statistics. A 10-year mortality follow-up of the Bern prevalence study]

Based on data from a multiple sclerosis (MS) prevalence study which had been carried out in 1986 in the canton of Berne, Switzerland, a follow-up was performed 10 years later to gather information on mortality in the original study population. The authors used information on residency and death as gathered from municipal offices and, additionally, by record-linkage with the Swiss cause of death statistics. Slightly more than 80% of the cases were identified unequivocally as of January 1996. Among them, 21% of the cases died during the ten-year period; 70% of them have an MS entry in the cause of death statistics, mostly as the main cause of death. A large proportion of the non-identifiable cases appear to be related to mortality; thus, the findings here do not provide a promising basis for certain further analyses. In conclusion, continuous updating of personal data is the only way to avoid loss to follow-up in the carefully assembled prevalence database.

Real-time MR-guided joint puncture and arthrography: preliminary results

The purpose of this study was to evaluate interactive MR-guided joint puncture with intra-articular application of contrast agent. MR-guided arthrography of the shoulder joint was successfully performed in three patients using an interactive guidance system implemented in an open-configuration MR system. Visualization of the needle pathway and contrast inflow was comparable to that with conventional X-ray fluoroscopy. The position of the intra-articular needle tip was accurately confirmed and subsequent MR arthrography was diagnostic in all cases.

Ectopic NORs on human chromosomes 4qter and 8q11: rare chromosomal variants detected in two families

Two different NOR bearing non-acrocentric chromosomes were detected during prenatal diagnosis performed on two probands because of advanced maternal age. In the first case, a chromosome 4 carried a NOR in the telomeric region of the long arm (4qs), while in the second case a NOR was inserted into chromosome 8q11. Family analysis showed the variant chromosomes to be transmitted through at least three generations in each family. There were no reports of reproductive problems or phenotypic effects in the carriers of these chromosomes, indicating the benign character of the aberrant chromosomes. In order to characterise the chromosomal variants more precisely, various differential banding techniques were applied.

Functional mammalian homologues of the Drosophila PEV-modifier Su(var)3-9 encode centromere-associated proteins which complex with the heterochromatin component M31

The chromo and SET domains are conserved sequence motifs present in chromosomal proteins that function in epigenetic control of gene expression, presumably by modulating higher order chromatin. Based on sequence information from the SET domain, we have isolated human (SUV39H1) and mouse (Suv39h1) homologues of the dominant Drosophila modifier of position-effect-variegation (PEV) Su(var)3-9. Mammalian homologues contain, in addition to the SET domain, the characteristic chromo domain, a combination that is also preserved in the Schizosaccharyomyces pombe silencing factor clr4. Chromatin-dependent gene regulation is demonstrated by the potential of human SUV39H1 to increase repression of the pericentromeric white marker gene in transgenic flies. Immunodetection of endogenous Suv39h1/SUV39H1 proteins in a variety of mammalian cell lines reveals enriched distribution at heterochromatic foci during interphase and centromere-specific localization during metaphase. In addition, Suv39h1/SUV39H1 proteins associate with M31, currently the only other characterized mammalian SU(VAR) homologue. These data indicate the existence of a mammalian SU(VAR) complex and define Suv39h1/SUV39H1 as novel components of mammalian higher order chromatin.

Identification and characterization of mouse homologue to yeast Cdc7 protein and chromosomal localization of the cognate mouse gene Cdc7l

The Cdc7 kinase is required for the G1/S-phase transition during the cell cycle and plays a direct role in the activation of individual origins of replication in Saccharomyces cerevisiae. Here, we report the identification of a mouse cDNA, MmCdc7, whose product is closely related in sequence to Saccharomyces cerevisiae Cdc7 as well as their human, Xenopus and Schizosaccharomyces pombe homologues. The MmCdc7p contains the conserved subdomains common to all protein-serine/threonine kinases and three kinase inserts that are characteristic of members of the Cdc7 protein family. We have mapped the locus of the MmCdc7 gene to chromosome 5, band 5E. Conservation of structures among members of the Cdc7-related proteins suggests that these proteins play a key role in the regulation of DNA replication during the cell cycle in all eukaryotes.

[Therapy studies of the Austrian Breast Cancer Group (ABC)]

The Austrian Breast Cancer Group (ABC) consisting of more than 60 participating centers in Austria has randomized more than 5800 patients in 11 randomized trials since 1984. At present, roughly 30% of all patients with the diagnosis primary breast cancer are accrued in protocols throughout the country. Due to specific activities, the breast conservation rate raised from an initial 20% to more than 60% in the last years. Multicenter trials are not only the basis for progress in medicine but also tools for quality control and quality improvement.

Dynamics of eicosanoids in peripheral blood cells during bronchial provocation in aspirin-intolerant asthmatics

The underlying mechanisms of bronchoconstriction in aspirin-intolerant asthmatics (AIAs) are still unknown, but the hypothesis of an altered metabolism of arachidonic acid is generally accepted. So far, no in vitro test for aspirin intolerance is available. The hypothesis that the profile of eicosanoid mediators is changed in AIA-even before aspirin challenge was tested. The release of prostaglandin E2 (PGE2), peptidoleukotrienes and histamine was measured using competitive enzyme immunoassays in 10 asthmatics with a history of aspirin intolerance, 10 controls and eight aspirin-tolerant asthmatics (ATAs) before and after bronchial provocation with lysine-aspirin. Comparing basal release of eicosanoids before challenge, peptidoleukotrienes were significantly elevated and PGE2 was vastly reduced in AIAs, whereas ATAs had elevated basal peptidoleukotrienes but only slightly reduced basal PGE2. The decrease in forced expiratory volume in one second (FEV1) was not associated with changes in histamine release. After aspirin challenge, there was a massive increase of already elevated peptidoleukotrienes in AIAs, but not in ATAs. Arachidonic acid-induced PGE2 release in AIAs was not significantly changed, whereas it was significantly reduced in ATAs and healthy controls. Histamine release was unaffected by aspirin challenge in all three groups. There is a typically altered profile of eicosanoids in aspirin-intolerant asthmatics which could make in vitro diagnosis of aspirin intolerance possible.

Arachidonic acid metabolism in nasal tissue and peripheral blood cells in aspirin intolerant asthmatics

Aspirin intolerance (AI) is characterized by polypous rhinosinusitis, bronchial asthma and adverse reactions to aspirin. The common intolerance to all cyclo-oxygenase inhibitors allows us to focus study of the pathogenesis of AI on the metabolism of arachidonic acid (AA). We studied the metabolism of AA in nine aspirin intolerant asthmatics (AIA) and eight healthy volunteers (controls) by measuring prostaglandin E2 (PGE2) and peptido-leukotrienes (pLT = LTC4/D4/E4) in nasal tissue and peripheral blood cells (PBCs) using a specific immunoassay. In all patients with AI the tests were performed before and after bronchial provocation with lysine-ASA. In the control group the tests were done before and after 500 mg ASA p.o. The release of pLT in nasal polyps of AIA was found to be significantly higher than in normal mucosa of AIAs and controls. In every tissue a significant increase of pLT after aspirin challenge was observed. Nasal polyps of AIA show a significantly lower release of PGE2 than normal mucosa of AIAs and controls. Peripheral blood cells of AIA show a significantly higher release of pLT and a significantly lower release of PGE2 than PBCs of controls. Therefore clinical manifestations of AI may be based on an alteration of AA metabolism in AIA.