Morphological parameters affecting false lumen thrombosis following type B aortic dissection: a systematic study based on simulations of idealized models

Type B aortic dissection (TBAD) carries a high risk of complications, particularly with a partially thrombosed or patent false lumen (FL). Therefore, uncovering the risk factors leading to FL thrombosis is crucial to identify high-risk patients. Although studies have shown that morphological parameters of the dissected aorta are related to FL thrombosis, often conflicting results have been reported. We show that recent models of thrombus evolution in combination with sensitivity analysis methods can provide valuable insights into how combinations of morphological parameters affect the prospect of FL thrombosis. Based on clinical data, an idealized geometry of a TBAD is generated and parameterized. After implementing the thrombus model in computational fluid dynamics simulations, a global sensitivity analysis for selected morphological parameters is performed. We then introduce dimensionless morphological parameters to scale the results to individual patients. The sensitivity analysis demonstrates that the most sensitive parameters influencing FL thrombosis are the FL diameter and the size and location of intimal tears. A higher risk of partial thrombosis is observed when the FL diameter is larger than the true lumen diameter. Reducing the ratio of the distal to proximal tear size increases the risk of FL patency. In summary, these parameters play a dominant role in classifying morphologies into patent, partially thrombosed, and fully thrombosed FL. In this study, we point out the predictive role of morphological parameters for FL thrombosis in TBAD and show that the results are in good agreement with available clinical studies.

     

The reproductive biology of Cyclops vicinus

Investigations of the reproductive biology of Cyclops vicinusrevealed that mated females oscillate between gravid and nongravidreproductive conditions. The gravid condition can be dividedin two recognizable phases: gravid/nonovigerous and gravid/ovigerous,the former phase being shortest. The maturation of new oocytestakes place when the old egg sacs are still being carried; thisensures a rapid clutch succession. Females which remain unmated,extrude few eggs, in no case complete egg sacs, and remain gravidthus conserving oocytes. Females which mate only once, showa similar reproductive pattern (clutch size and clutch succession)to those which remain combined with males, and thus have theopportunity to remate, but tend to produce fewer clutches. Malesare able to fertilize 3–4 females day^–1. Matingcapacity of males is possibly limited by the time needed tofill a new spermatophore. Short-term starvation (5 days) lengthenedclutch-to-clutch periods and diminished clutch size. When thestarvation period started in the gravid/ovigerous phase, a normalclutch was extruded but no new oocytes matured during starvation,indicating that the energy for egg maturations is provided inthe first part of the reproductive cycle.     

Importance of Silene latifolia ssp. alba and S. dioica (Caryophyllaceae) as host plants of the parasitic pollinator Hadena bicruris (Lepidoptera, Noctuidae)

With regards to pollination there exist several mutualistic relationships between Hadena -species and Caryophyllaceae. As mutualists have both negative and positive effects on their partners, mutualism is often betoken as reciprocative exploitation which may shift to parasitism if the exploitation of one partner becomes prevalent.
Several Silene - and Saponaria -species are considered to be larval host plants of Hadena bicruris . Although Silene latifolia ssp. alba and S. dioica are frequently cited as hosts of the seed eating larvae, field and laboratory observations at Ulm were suggestive for only S. latifolia ssp. alba being a suitable host. Records of the oviposition behavior of H. bicruris made it evident that in fact a considerable number of eggs could be found in planted stands of both species. On the other hand, phenological data of the flowering periods and of the oviposition behavior of H. bicruris showed that S. latifolia ssp. alba is clearly preferred for oviposition if host selection is possible due to contemporaneous flowering of individuals of both plant species growing at close range. In addition, the flowering periods of S. latifolia ssp. alba and the periods of moth activity overlap to a large extent. This is not the case in S. dioica . Feeding experiences first indicated that the caterpillars may not prefer one of the species to the other, but comparison of the pupal weight of the animals reared on fruits of exclusively one of the species showed that the seeds of S. latifolia ssp. alba were more profitable for nutrition than those of S. dioica ; the pupal weight of animals reared on seeds of the former species significantly exceeded that of animals reared on seeds of the latter one. The question arises if the symbiosis of H. bicruris and its hosts constitutes a stable situation or if an evolutionary shift to mutualism or parasitism will take place.     

Methods for the separation of lactate dehydrogenases and clinical significance of the enzyme

Lactate dehydrogenase (LDH), an ubiquitous enzyme among vertebrates, invertebrates, plants and microbes was discovered in the early period of enzymology. The enzyme has been dissolved in several distinguishable molecular forms. In mammals, three types of subunits encoded by the genes Ldh-A, Ldh-B and Ldh-C give rise to a selected number of tetrametric isoenzymes. LDH-A₄, LDH-B₄ and the mixed hybrid forms of the A- and B-subunits are present in many tissues but with certain distribution patterns. LDH-C₄ is confined in mammals to testes and sperm. Numerous techniques have been employed to purify, characterize and separate the different forms of the enzyme. This report deals with the main protocols and procedures of purification of LDH and its isoenzymes including chromatographic and electrophoretic methods, partitioning in aqueous two-phase systems and precipitation approaches. In particular, affinity separation techniques based on natural and pseudo-biospecific ligands are described in detail. In addition, basic physico-chemical and kinetic properties of the enzyme from different sources are summarized. In a second part, the clinical significance of the determination of LDH in diverse body fluids in respect to the total activity and the isoenzyme distribution in different organs is discussed.     

Desferrioxamine-dependent iron transport in Erwinia amylovora CFBP1430: cloning of the gene encoding the ferrioxamine receptor FoxR

Iron deprivation of Erwinia amylovora CFBP1430, a species causing fire blight on Pomoïdeae, was shown to induce the production of siderophores of the desferrioxamine (dfo) family and two outer membrane polypeptides with apparent molecular weight of about 70 and 80 kDa, respectively. Cyclic dfo E was characterized as the major metabolite. Phage MudII_pR13 insertional mutagenesis and screening on CAS-agar medium yielded three dfo non-producing and one overproducing clones. These clones failed to grow in the presence of the Fe(III) chelator EDDHA and were determined further as dfo and ferrioxamine transport negative mutants, respectively. The transport mutant which appeared to lack the 70 kDa polypeptide in the outer membrane allowed the purification of dfo E. Growth under iron limitation of dfo negative mutants was stimulated with ferrioxamine E and B but not with other ferrisiderophores tested. The host DNA sequence flanking the left terminal part of the MudII_pR13 prophage responsible for the transport mutation was cloned and used to probe a parental gene library by DNA-DNA hybridization. Two recombinant cosmids restoring the transport mutation to normal were identified. Both cosmids also conferred the ability to utilize ferrioxamine B and E as iron sources on a FhuE¹ mutant of Escherichia coli. This correlated with the production of an additional polypeptide of 70 kDa in the outer membrane of E. coli transconjugants, thus confirming that this protein serves the ferrioxamine receptor function (FoxR) in E. amylovora.R. Kachadourian and A. Dellagi have contributed equally to this work.     

Fluorescence in situ hybridization with cosmid clones for the detection of human cytomegalovirus DNA in peripheral blood leukocytes

 Radioactive in situ hybridization techniques or enzymatic detection procedures of hapten-modified human cytomegalovirus (HCMV) probes have been widely used for studying the infection of peripheral blood leukocytes with HCMV. This report describes significant improvements in terms of signal resolution which can be obtained by applying a highly sensitive fluorescence in situ hybridization (FISH) technique in conjunction with a large subgenomic HCMV DNA probe. Three cosmid clones spanning 119.1 kb of the HCMV genome (230 kb) were used to construct the digoxigenin-11-dUTP-labeled probe which was found to be superior to a total HCMV probe representing the entire genome. Crucial hybridization parameters were analyzed systematically in order to ensure optimal resolution power and sensitivity. The protocol was successfully applied to HCMV-infected fibroblasts and peripheral blood leukocytes of 12 transplant patients and unambiguously facilitated the precise intracellular localization of HCMV genomes in infected cells. Because of its excellent resolution properties, accompanied by the virtual absence by any background staining, we recommend the use of this protocol as a sensitive approach for further virological analyses of the interactions between HCMV and peripheral blood leukocytes at the single-cell level. Accepted: 16 February 1996     

Glial cells phagocytose neuronal debris during the metamorphosis of the central nervous system in Drosophila melanogaster

 Using electron microscopy we demonstrate that degenerating neurons and cellular debris resulting from neuronal reorganization are phagocytosed by glial cells in the brain and nerve cord of the fruitfly Drosophila melanogaster during the first few hours following pupariation. At this stage several classes of glial cells appear to be engaged in intense phagocytosis. In the cell body rind, neuronal cell bodies are engulfed and phagocytosed by the same glial cells that enwrap healthy neurons in this region. In the neuropil, cellular debris in tracts and synaptic centres resulting from metamorphic re-differentiation of larval neurons is phagocytosed by neuropil-associated glial cells. Phagocytic glial cells are hypertrophied, produce large amounts of lysosome-like bodies and contain a large number of mitochondria, condensed chromatin bodies, membranes and other remains from neuronal degeneration in phagosomes. Received: 23 January 1996 / Accepted in revised form: 21 May 1996     

A cyclophilin-like peptidyl-prolyl cis/trans isomerase from Legionella pneumophila – characterization, molecular cloning and overexpression

Legionella pneumophila is the causative agent of a severe form of pneumonia in humans (Legionnaires’disease). A major virulence factor, the Mip protein (FK506-binding protein, FKBP25mem), belongs to the enzyme family of peptidyl-prolyl cis/trans isomerases (PPIases). Here we show that L. pneumophila Philadelphia I possesses an additional cytoplasmic PPiase at a level of enzyme activity comparable to that of FKBP25mem. The N-terminal amino acid sequence of the purified protein was obtained by Edman degradation and showed that the protein is a member of the cyclophilin family of PPIases. The Icy gene (Legionella cycophn) was cloned and sequenced. It encodes a putative 164-amino-acid protein with a molecular mass of 17 968 Da called L. pneumophila cyclophilin 18 (L. p. Cyp18). Amino acid sequence comparison displays considerable similarity to the cytoplasmic and the periplasmic cyclophilins of Escherichia coll with 60.5% and 51.5% identity, respectively. The substrate specificity and inhibition by cyclosporin A revealed a pattern that is typically found for other bacterial cyclophilins. An L. pneumophila Cyp18 derivative with a 19-amino-acid polypeptide extension including a 6-histi-dine tag and an enterokinase cleavage site exhibits