Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of connective tissue diseases, collectively known as myositis. Diagnosis of IIM is challenging while timely recognition of an IIM is of utter importance considering treatment options and otherwise irreversible (severe) long-term clinical complications. With the EULAR/ACR classification criteria (2017) considerable advancement has been made in the diagnostic workup of IIM. While these criteria take into account clinical parameters as well as presence of one autoantibody, anti-Jo-1, several autoantibodies are associated with IIM and are currently evaluated to be incorporated into classification criteria. As individual antibodies occur at low frequency, the development of line blots allowing multiplex antibody analysis has improved laboratory diagnostics for IIM. The Euroline myositis line-blot assay (Euroimmun) allows screening and semi-quantitative measurement for 15 autoantibodies, i.e . myositis specific antibodies (MSA) to SRP, EJ, OJ, Mi-2α, Mi-2β, TIF1-γ, MDA5, NXP2, SAE1, PL-12, PL-7, Jo-1 and myositis associated antibodies (MAA) to Ku, PM/Scl-75 and PM/Scl-100. To evaluate the clinical significance of detection and levels of these autoantibodies in the Netherlands, a retrospective analysis of all Dutch requests for extended myositis screening within a 1 year period was performed. A total of 187 IIM patients and 632 non-IIM patients were included. We conclude that frequencies of MSA and MAA observed in IIM patients in a routine diagnostic setting are comparable to cohort-based studies. Weak positive antibody levels show less diagnostic accuracy compared to positive antibody levels, except for anti-NXP2. Known associations between antibodies and skin involvement (anti-MDA5, anti-TIF1-γ), lung involvement (anti-Jo-1), and malignancy (anti-TIF1-γ) were confirmed in our IIM study population. The availability of multiplex antibody analyses will facilitate inclusion of additional autoantibodies in clinical myositis guidelines and help to accelerate diagnosing IMM with rare but specific antibodies.

The outer membrane protein OmpX of Enterobacter cloacae shows high amino acid homology with virulence proteins PagC and Rck from Salmonella typhimurium and with Ail from Yersinia enterocolitica. Here we demonstrate a role for OmpX in the invasion of rabbit ileal tissue by E. cloacae. An organ culture system was used for maintenance of rabbit gut tissue during the experiments. The invasivenesses of three E. cloacae strains, which differed in OmpX content, were compared with each other and with that of Salmonella typhimurium TML (a highly invasive strain) and S. typhimurium LT7 (a noninvasive strain). There was no significant difference between the invasiveness of the wild type and that of an ompX deletion mutant strain of E. cloacae; they were equally as invasive or less invasive than S. typhimurium LT7. The invasiveness of an OmpX overproducer strain of E. cloacae was 10-fold higher than that of its immediate parent carrying only the multicopy plasmid, higher than that of S. typhimurium LT7, but lower than that of S. typhimurium TML. The invasiveness of E. cloacae thus varied directly with the level of OmpX in the outer membrane in rabbit ileal

The localization of transcripts of the pollenspecific gene NTP303 has been determined by means of in situ hybridization in combination with confocal laser 1987; Blackm ore and Knox. 1990; Bedinger 1992; O tta viano et a l 1992), including m olecular biology (M ascarenhas 1990; M cC orm ick et al. 1991; Scott et al. scanning microscopy. NTP303 transcripts were first de-1991b; W eterings et al. 1992). The study o f pollen developm ent is of considerable agronom ic im portance for plant breeding, propagation, and seed production. A t the sam e time, it is also an intriguing as well as a convenient m odel system to study the m echanism of gene regulation. The pollen genom e is haploid and is actively transcribed. Specific transcripts in the m icrospore and pollen grain appear and disap pear during its synchronous developm ent (Schrauwen e ta l. 1990; Scott et al. 1991a), In the m ature pollen grain, the vegetative cell and the generative cell or its derivatives, the sperm cells, have their own specialized functions. Clearly the delegation of tasks to the different cells of the m ale gam etophyte must im plicate a cellspecific regulation of genes. T hese properties, together with the relative ease of isolation, m ake the pollen grain a very suitable object for m olecular biological studies. We have set out to study gene regulation during p o l len developm ent by isolating a pollen-specific c D N A clone-NTPc3Q3-from Nicotiana tabacum (Weterings In flowering plants, the male gametophyte has been re-et al. 1992). N T P 303 R N A is n ot detectable in sporo-tectable at the mid-bi-nucleate stage of pollen develop ment and persisted even after the pollen tube had reached the ovary. The majority of the NTP303 tran scripts were localized in the vegetative cell, and were predominantly present in the apex of the pollen tube. To study the mechanism of regulation, the genomic clone NTPg303 was isolated and characterized. NTPg303 be longs to a gene family of at least five members. N o in trons are present in its coding region. Regions matching the pollen-specific PB-element TG TG G TT (Twell et al. 1991) have been found.

The penicillin-binding proteins (PBPs) of five penicillin tolerant group A streptococci and their isogenic non-tolerant strains, and seven unrelated non-tolerant group A streptococci were compared. PBPs from late logarithmic cultures were labelled in vitro with 3H-benzylpenicillin and analysed by SDS-PAGE and fluorography. The PBP patterns for all non-tolerant strains were identical. This pattern differed markedly from that for penicillin tolerant strains, both qualitatively and quantitatively. The most striking change in penicillin tolerant strains was decreased binding of 3H-penicillin to PBP 3 and increased binding to PBP 5, while PBP 2a was replaced by a new PBP (PBP 2a') of lower electrophoretic mobility. Tolerance was lost during storage but could be restored by consecutive transfers on to penicillin gradient agar plates. At the same time the PBP profiles of these strains became identical to those found for stable tolerant strains. These results suggest the possibility that PBP 2a' and PBP 5 in combination with other PBP alterations play a role in penicillin tolerance found in group A streptococci.

The Enterobacter cloacae outer membrane protein OmpX is involved in resistance to beta-lactams, and possesses virulence characteristics. To gain more insight into the genetic elements that are important for OmpX expression, several mutations were introduced at, and immediately upstream of, the N-terminus of the OmpX coding sequence. These mutations enabled us to delete the 5' untranslated region and the signal peptide coding sequence. The former led to decreased ompX expression, indicating an unexpected and hitherto unexplained role for this region. Deletion of the signal peptide coding sequence blocked transport across the cytoplasmic membrane, indicating that translocation of OmpX across the cytoplasmic membrane is mediated by the general secretory pathway.