Subgenome dominance shapes novel gene evolution in the decaploid pitcher plant Nepenthes gracilis

Subgenome dominance after whole-genome duplication generates distinction in gene number and expression at the level of chromosome sets, but it remains unclear how this process may be involved in evolutionary novelty. Here we generated a chromosome-scale genome assembly of the Asian pitcher plant Nepenthes gracilis to analyse how its novel traits (dioecy and carnivorous pitcher leaves) are linked to genomic evolution. We found a decaploid karyotype and a clear indication of subgenome dominance. A male-linked and pericentromerically located region on the putative sex chromosome was identified in a recessive subgenome and was found to harbour three transcription factors involved in flower and pollen development, including a likely neofunctionalized LEAFY duplicate. Transcriptomic and syntenic analyses of carnivory-related genes suggested that the paleopolyploidization events seeded genes that subsequently formed tandem clusters in recessive subgenomes with specific expression in the digestive zone of the pitcher, where specialized cells digest prey and absorb derived nutrients. A genome-scale analysis suggested that subgenome dominance likely contributed to evolutionary innovation by permitting recessive subgenomes to diversify functions of novel tissue-specific duplicates. Our results provide insight into how polyploidy can give rise to novel traits in divergent and successful high-ploidy lineages.

Transient Recurrent Laryngeal Nerve Palsy after Interventional Therapy

BACKGROUND

 Hoarseness due to laryngeal nerve injury is a known complication after cardiothoracic surgery involving the aortic arch. However, this complication is only rarely reported after catheter interventions.

RESULTS

 In this article we present the unusual case of a left-sided vocal cord paralysis in four patients after primary stenting of a re-coarctation, re-dilatation of a stented coarctation, a primary stenting of the left pulmonary artery (LPA), and prestenting for percutaneous pulmonary valve implantation with dilation of the LPA. After implanting bare metal stents, it is common practice, whilst contemplating the diameters of the adjacent structures, to optimize the stent diameter in a two-step procedure and dilate the stent until a maximum diameter is achieved and there is no residual gradient after applying this technique. Four of our patients experienced hoarseness after the intervention and a vocal cord paralysis was diagnosed. Angiography revealed no signs of extravasation or dissection. Clinical symptoms improved over the course of the following 6 months; patients with interventions at the aortic arch showed a complete remission, patients with procedures involving the LPA showed only mild regression of the symptoms.

CONCLUSION

 To our knowledge, this complication (Ortner's syndrome, cardiovocal syndrome) after such interventions has rarely been reported before. Although a rare complication, the recognition of these symptoms may support colleagues in managing affected patients. In addition, awareness for hoarseness after interventional therapies and systematic screening for this complication might help to identify patients at risk in the future.

The digestive systems of carnivorous plants

To survive in the nutrient-poor habitats, carnivorous plants capture small organisms comprising complex substances not suitable for immediate reuse. The traps of carnivorous plants, which are analogous to the digestive systems of animals, are equipped with mechanisms for the breakdown and absorption of nutrients. Such capabilities have been acquired convergently over the past tens of millions of years in multiple angiosperm lineages by modifying plant-specific organs including leaves. The epidermis of carnivorous trap leaves bears groups of specialized cells called glands, which acquire substances from their prey via digestion and absorption. The digestive glands of carnivorous plants secrete mucilage, pitcher fluids, acids, and proteins, including digestive enzymes. The same (or morphologically distinct) glands then absorb the released compounds via various membrane transport proteins or endocytosis. Thus, these glands function in a manner similar to animal cells that are physiologically important in the digestive system, such as the parietal cells of the stomach and intestinal epithelial cells. Yet, carnivorous plants are equipped with strategies that deal with or incorporate plant-specific features, such as cell walls, epidermal cuticles, and phytohormones. In this review, we provide a systematic perspective on the digestive and absorptive capacity of convergently evolved carnivorous plants, with an emphasis on the forms and functions of glands.

Under salt stress guard cells rewire ion transport and abscisic acid signaling

Soil salinity is an increasingly global problem which hampers plant growth and crop yield. Plant productivity depends on optimal water-use efficiency and photosynthetic capacity balanced by stomatal conductance. Whether and how stomatal behavior contributes to salt sensitivity or tolerance is currently unknown. This work identifies guard cell-specific signaling networks exerted by a salt-sensitive and salt-tolerant plant under ionic and osmotic stress conditions accompanied by increasing NaCl loads. We challenged soil-grown Arabidopsis thaliana and Thellungiella salsuginea plants with short- and long-term salinity stress and monitored genome-wide gene expression and signals of guard cells that determine their function. Arabidopsis plants suffered from both salt regimes and showed reduced stomatal conductance while Thellungiella displayed no obvious stress symptoms. The salt-dependent gene expression changes of guard cells supported the ability of the halophyte to maintain high potassium to sodium ratios and to attenuate the abscisic acid (ABA) signaling pathway which the glycophyte kept activated despite fading ABA concentrations. Our study shows that salinity stress and even the different tolerances are manifested on a single cell level. Halophytic guard cells are less sensitive than glycophytic guard cells, providing opportunities to manipulate stomatal behavior and improve plant productivity.

Genomes of the Venus Flytrap and Close Relatives Unveil the Roots of Plant Carnivory

Most plants grow and develop by taking up nutrients from the soil while continuously under threat from foraging animals. Carnivorous plants have turned the tables by capturing and consuming nutrient-rich animal prey, enabling them to thrive in nutrient-poor soil. To better understand the evolution of botanical carnivory, we compared the draft genome of the Venus flytrap (Dionaea muscipula) with that of its aquatic sister, the waterwheel plant Aldrovanda vesiculosa, and the sundew Drosera spatulata. We identified an early whole-genome duplication in the family as source for carnivory-associated genes. Recruitment of genes to the trap from the root especially was a major mechanism in the evolution of carnivory, supported by family-specific duplications. Still, these genomes belong to the gene poorest land plants sequenced thus far, suggesting reduction of selective pressure on different processes, including non-carnivorous nutrient acquisition. Our results show how non-carnivorous plants evolved into the most skillful green hunters on the planet.

Species Specific Immunoassays to Measure Blood Platelet and Coagulation Activation in the Rat

The purpose of this study was to develop specific and sensitive immunoassays to detect early indices of hypercoagulability in the rat. Rat platelet factor 4 (rPF4) and rat fibrinopeptide A (rFPA) assays, tools for the detection of activation of platelets and coagulation respectively, were designed using antibodies raised against purified rPF4 and against synthetic rFPA. The relevance of these new assays and of the commercially available ELISA kit for thrombin-antithrombin III (TAT) complexes was demonstrated in a rat model of a prethrombotic state induced by intravenous infusion of varying doses of thromboplastin (90 to 2400 μl/kg/h). In this model, the immunoassays allowed simultaneous detection of low levels of rFPA and rPF4 which were correlated with fibrinogen and platelet consumption and TAT generation and further proved to be of higher sensitivity than the classical methods of platelet count or measurement of fibrinogen levels. Plasma concentrations of rFPA, rPF4 and TAT were dependent on infusion time and thromboplastin dose, while hirudin (1 mg/kg) prevented their appearance. Thus the new specific immunoassays for rPF4 and rFPA and the commercial human TAT assay represent useful tools for pathophysiological studies or the screening of antithrombotic drugs in rats.

Lentiviral gene rescue of a Bernard-Soulier mouse model to study platelet glycoprotein Ibβ function

Essentials A signaling role of glycoprotein (GP)Ibβ is postulated but not formally demonstrated in platelets. Lentiviral-mediated rescue in knock-out mice can be used to evaluate GPIbβ function in vivo. Transduction of the native subunit corrected the main defects associated with GPIb-IX deficiency Deletion of intracellular 159-170 segment increased thrombosis, 150-160 removal increased bleeding.

SUMMARY

Background The platelet glycoprotein (GP)Ib-V-IX complex is required for normal hemostasis and megakaryopoiesis. A role in GPIb-dependent responses has been ascribed to the less well characterized GPIbβ subunit using a specific antibody and GPIb-IX transfected cells. Objectives Our aim was to evaluate, in vivo, the role of the GPIbβ in hemostasis and thrombosis. Methods GPIbβ(null) Sca-1(+) progenitors transduced with viral particles harboring hGPIbβ were transplanted into lethally irradiated GPIbβ(-/-) recipient mice. Results hGPIbβ transplanted into the bone marrow of GPIbβ(null) mice rescued GPIb-IX expression in 97% of circulating platelets. These platelets efficiently bound von Willebrand factor (VWF) and extended filopodia on a VWF matrix, demonstrating the restoration of GPIb-dependent adhesive and signaling properties. These mice exhibited less severe macrothrombocytopenia and had normal tail bleeding times as compared with GPIbβ(null) mice. This strategy was employed to manipulate and evaluate the role of the GPIbβ intracellular domain. Removal of the membrane proximal segment (Δ(150-160) ) decreased GPIb-IX expression by 43%, confirming its involvement in receptor assembly and biosynthesis, and resulted in increased bleeding times and decreased thrombosis in a mechanical injury model in the aorta. On the other hand, deletion of the C-flanking 159-170 segment allowed normal GPIb-IX expression, VWF-dependent responses and bleeding times, but resulted in enhanced arterial thrombosis. Conclusion This pointed to a repressor role of GPIbβ in thrombus formation in vivo that was not predicted in studies of heterologous cells. These results highlight the utility of this lentiviral strategy for the structure-function evaluation of GPIb-IX in platelets.

Characterization of the symbiont Rickettsia in the mirid bug Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae)

Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae) is an omnivorous insect used for biological control. Augmentative release and conservation of N. tenuis have been used for pest control in tomato crops. Intracellular bacterial symbionts of arthropods are common in nature and have diverse effects on their hosts; in some cases they can dramatically affect biological control. Fingerprinting methods showed that the symbiotic complex associated with N. tenuis includes Wolbachia and Rickettsia. Rickettsia of N. tenuis was further characterized by sequencing the 16S rRNA and gltA bacterial genes, measuring its amount in different developmental stages of the insect by real-time polymerase chain reaction, and localizing the bacteria in the insect's body by fluorescence in situ hybridization. The Rickettsia in N. tenuis exhibited 99 and 96% similarity of both sequenced genes to Rickettsia bellii and Rickettsia reported from Bemisia tabaci, respectively. The highest amount of Rickettsia was measured in the 5th instar and adult, and the symbionts could be detected in the host gut and ovaries. Although the role played by Rickettsia in the biology of N. tenuis is currently unknown, their high amount in the adults and localization in the gut suggest that they may have a nutritional role in this insect.

Effects of the angiotensin-(1-7) receptor Mas on cell proliferation and on the population of doublecortin positive cells within the dentate gyrus and the piriform cortex

Aside from the well-known biologically active angiotensin II, other biologically active angiotensins have been discovered, including angiotensin IV and angiotensin-(1-7). Some years ago, we and others discovered that the Mas proto-oncogene encodes a G protein-coupled receptor being essential for angiotensin-(1-7) signaling. Mas is not only expressed in the periphery but also within the brain, e.g. in the dentate gyrus (DG) and the piriform cortex (PC). Since the DG is capable of adult neurogenesis, we examined the impact of a deletion of Mas upon adult neurogenesis. Deletion of Mas did not alter cell proliferation in the adult DG (as monitored with phosphohistone H3) and did not alter cell death (as monitored with activated Caspase 3). However, Mas deficiency resulted in an increase in the number of doublecortin (DCX) positive cells, indicating that lack of Mas increases the number of this cell population. Concerning the PC, it is discussed whether adult neurogenesis occurs under physiological conditions in this area. We could demonstrate that Mas deficiency has an impact on cell division and on the population of DCX-positive cells within the PC. Since Mas is not expressed before birth within the brain, our data may suggest that adult hippocampal neurogenesis and neurogenesis occurring during prenatal development share several common mechanisms, but are, at least in part, differentially regulated. Moreover, since deficiency for Mas increases the numbers of DCX-positive young neurons, blockage of Mas might be beneficial in stimulating neurogenesis in adults.

Breast cancer-associated missense mutants of the PALB2 WD40 domain, which directly binds RAD51C, RAD51 and BRCA2, disrupt DNA repair

Heterozygous carriers of germ-line mutations in the BRCA2/FANCD1, PALB2/FANCN and RAD51C/FANCO DNA repair genes have an increased lifetime risk of developing breast, ovarian and other cancers; bi-allelic mutations in these genes clinically manifest as Fanconi anemia (FA). Here, we demonstrate that RAD51C is part of a novel protein complex that contains PALB2 and BRCA2. Further, the PALB2 WD40 domain can directly and independently bind RAD51C and BRCA2. To understand the role of these homologous recombination (HR) proteins in DNA repair, we functionally characterize effects of missense mutants of the PALB2 WD40 domain that have been reported in breast cancer patients. In contrast to large truncations of PALB2, which display a complete loss of interaction, the L939W, T1030I and L1143P missense mutants/variants of the PALB2 WD40 domain are associated with altered patterns of direct binding to the RAD51C, RAD51 and BRCA2 HR proteins in biochemical assays. Further, the T1030I missense mutant is unstable, whereas the L939W and L1143P proteins are stable but partially disrupt the PALB2-RAD51C-BRCA2 complex in cells. Functionally, the L939W and L1143P mutants display a decreased capacity for DNA double-strand break-induced HR and an increased cellular sensitivity to ionizing radiation. As further evidence for the functional importance of the HR complex, RAD51C mutants that are associated with cancer susceptibility and FA also display decreased complex formation with PALB2. Together, our results suggest that three different cancer susceptibility and FA proteins function in a DNA repair pathway based upon the PALB2 WD40 domain binding to RAD51C and BRCA2.

Expression and prognostic significance of hsa-miR-142-3p in acute leukemias

OBJECTIVES

The microRNA 142 (miR-142) is expressed at high levels in mature hematopoietic cells and has a crucial role during T-lymphocyte development. Its role in leukemogenesis is unclear.

PATIENTS AND METHODS

Expression of miR-142 was analyzed in acute myeloid and lymphoblastic leukemia cells (de novo, cell lines). Data were compared to expression in CD34+ hematopoietic cells. Based on the miR-142 expression, clinical data such as overall survival was analyzed.

RESULTS

MiR-142 expression in all leukemia cell lines and 86 % of the de novo samples was higher than in CD34+ cells. This difference could be detected in both, myeloid and lymphoid neoplastic cells. In AML patients with intermediate cytogenetic risk a high miR-142 expression was associated with a better overall survival.

CONCLUSIONS

MiR-142 expression in acute lymphoblastic as well as myeloid leukemia cells is higher than in CD34+ cells. Additionally, miR-142 expression might have prognostic relevance in AML-patients with otherwise an intermediate cytogenetic risk.

Mobilization of PBSC for allogeneic transplantation by the use of the G-CSF biosimilar XM02 in healthy donors

The human recombinant G-CSF filgrastim has been widely used for the mobilization of CD34⁺ stem cells of healthy donors (HD). In 2008, the G-CSF biosimilar XM02 (Ratiograstim, Tevagrastim and Biograstim) was approved by the European Medicines Agency (EMA) for the mobilization of PBSC. However, there is limited experience in the application of biosimilar G-CSF for the mobilization of PBSC especially in HD. Therefore, we investigated in two cohorts (n=22), the efficacy and safety of PBSC mobilization by either biosimilar G-CSF or reference G-CSF. We observed a similar yield of CD34⁺ stem cells as well as CD3⁺ T-cells and nucleated cells in both groups and a safe engraftment in all patients with similar reconstitution of hematopoiesis in all hosts. In summary, we found a comparable efficacy and safety of biosimilar G-CSF when compared with reference G-CSF.

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

A new guanidine-thiourea organocatalyst has been developed and applied as bifunctional organocatalyst in the Michael addition reaction of diethyl malonate to trans-β-nitrostyrene. Extensive DFT calculations, including solvent effects and dispersion corrections, as well as ab initio calculations provide a plausible description of the reaction mechanism.

Personality influences quality-of-life assessments in adult patients after allogeneic hematopoietic SCT: results from a joint evaluation of the prospective German Multicenter Validation Trial and the Fred Hutchinson Cancer Research Center

The influence of personality on health related quality of life (QoL) and physical functioning in the setting of allogeneic hematopoietic SCT (alloHSCT) is unknown. We conducted a joint evaluation within two independent cohorts of alloHSCT recipients to investigate the impact of personality on reported QoL and physical functioning. Two-hundred-eight patients (median age 44 years, range 18-72) of cohort 1 and 93 patients (median age 55 years, range 19-79) of cohort 2 after alloHSCT were evaluated. Personality was assessed using the 24-adjective measure (AM), which measures the Big-Five personality domains and the Life Orientation Test-Revised (LOT-R), measuring optimism and pessimism. QoL was measured using the Functional Assessment of Cancer Therapy with bone marrow transplantation subscale (FACT-BMT), Short Form 36 (SF-36), the human activity profile (HAP), as well as the NIH criteria-based cGVHD activity assessment form and the Lee cGVHD symptom scale. Neuroticism was significantly associated with worse function measured by the HAP and FACT-BMT. Optimism significantly improved QoL captured by the FACT-BMT. Pessimism significantly impaired physical function captured by the HAP and SF-36. Extraversion was significantly associated with reduced depression and lower severity of cGVHD symptoms reported by the patient and the physician. The results suggest that personality traits and pre-treatment QoL assessments should be measured in clinical trials to facilitate the interpretation of QoL data.

Squamous cell carcinomas of the head and neck in Fanconi anemia: risk, prevention, therapy, and the need for guidelines

Fanconi anemia (FA) is a rare recessive DNA repair disorder that is clinically characterized by congenital malformations, progressive bone marrow failure, and increased incidence of malignancies, especially acute myeloid leukemia and squamous cell carcinomas of the head and neck (HNSCCs) and the anogenital regions. On a cellular level, typical features of the disorder are a high degree of genomic instability and an increased sensitivity to bi-functionally alkylating agents. So far, germ-line defects in 15 different FA genes have been identified. Some of these FA genes are also established as tumor susceptibility genes for familiar cancers.In recent years, the prevention and therapy of HNSCCs in FA patients has become more important as the percentage of patients surviving into adulthood is rising. HNSCCs appear in very young FA patients without common risk factors. Since cisplatin-based chemotherapy in combination with radiotherapy, essential parts of the standard treatment approach for sporadic HNSCCs, cannot be used in FA patients due to therapy-associated toxicities and mortalities even with reduced dosing, surgery is the most important treatment option for HNSCCs, in FA patients and requires an early and efficient detection of malignant lesions. So far, no uniform treatment protocol for the management of HNSCCs in FA patients exists. Therefore, we propose that the information on affected FA patients should be collected worldwide, practical therapeutic guidelines developed and national treatment centers established.

Early versus late administration of pegfilgrastim after high-dose chemotherapy and autologous hematopoietic stem cell transplantation

PURPOSE

Single-dose pegylated filgrastim (pegfilgrastim) after autologous hematopoietic stem cell transplantation (AHSCT) showed similar efficacy compared to daily lenograstim. To address the question of the optimal application time, we randomly assigned patients (pts) to pegfilgrastim on day + 1 (Peg1) or day + 4 (Peg4) after AHSCT.

METHOD

Fifty-three pts with different hematological malignancies were included in this prospective randomized multicenter study. Primary endpoint of this study was time to neutrophil recovery (>500 Gpt/l), and secondary endpoint was time to neutrophil recovery (>1,000 Gpt/l), platelet recovery (>20,000 Gpt/l), number and duration of febrile episodes, i.v. antibiotics, and number of transfusions. Time to engraftment endpoints were estimated according to Kaplan-Meier.

RESULTS

Median time to neutrophil recovery (>500 Gpt/l) was 10 days (95% CI: 10-11) in Peg1 versus 10 days (95% CI: 10-11) in Peg4 (P = 0.68, logrank test; hazard ratio: 0.93). The corresponding mean values were 10.2 and 10.4 days. Median time to platelet recovery (>20,000 Gpt/l) was 10 (95% CI: 10-11) in Peg1 versus 10 (95% CI: 9-11) in Peg4, again not significantly different (P = 0.54). There was no difference regarding the incidence (67% vs. 60%, P = 0.77, Fisher's exact test) or duration of febrile neutropenia episodes in both groups (median: 1 vs. 1; mean: 2.8 vs. 2.4 days; P = 0.73, Wilcoxon test).

CONCLUSION

In terms of neutrophil or platelet recovery after AHSCT, number and duration of febrile episodes, the use of i.v. antibiotics, early and late administration of pegfilgrastim are equally effective.

Allogeneic hematopoietic SCT in patients with AML following treosulfan/fludarabine conditioning

An alternative reduced-toxicity conditioning regimen for allogeneic transplantation, based on treosulfan and fludarabine, has recently been identified. The safety and efficacy of this new conditioning regimen has been investigated prospectively in patients with AML. A total number of 75 patients with AML in CR were treated with 3 × 14 g/m(2) treosulfan and 5 × 30 mg/m(2) fludarabine, followed by matched sibling or unrelated SCT. Patients were evaluated for engraftment, adverse events, GVHD, and for non-relapse mortality, relapse incidence, overall and disease-free survival (DFS). All patients showed primary engraftment of neutrophils after a median of 20 days. Non-hematological adverse events grade III-IV in severity included mainly infections (59%) and gastrointestinal symptoms (7%). Acute GVHD grade II-IV occurred in 21% and extensive chronic GVHD occurred in 16% of the patients. After a median follow-up of 715 days, the 2-year overall and DFS estimates were 61% and 55%, respectively. The 2-year incidences of relapse and non-relapse mortality reached 34% and 11%, respectively. In summary, our data confirm promising safety and efficacy of the treosulfan-based conditioning therapy in AML patients, ClinicalTrials.gov Identifier: NCT01063660.

[Recurrent hypoglycemia and a large intraabdominal tumor in a 61-year-old woman]

HISTORY AND ADMISSION FINDINGS

A 61-year-old woman was found unconscious by her husband. The emergency doctor detected hypoglycemia (blood glucose 1.7 mmol/l). This was the first such event, the patient had not been known to have diabetes mellitus. At admission the physical examination and the laboratory findings revealed no abnormalities.

INVESTIGATIONS

A fasting test was aborted shortly after the start because of the onset of neurological symptoms. An insulinoma was excluded by detecting suppressed levels of insulin and C-peptide. Computed tomography of the abdomen revealed a mesenteric tumour of 9 cm in diameter, which was identified immunhistologically as a grade 1 follicular lymphoma (FL).  After exclusion of endocrinological causes the recurrent hypoglycaemia was diagnozed as part of a paraneoplastic syndrome associated with a non-islet cell tumour hypoglycaemia (NICTH) with a newly diagnosed FL.

TREATMENT AND COURSE

Specific medication with the CD20 antibody rituximab (375 mg/m2, once per week for a total of four cycles) was initiated. There were no further episodes of hypoglycaemia. After one year the patient remains free of any symptoms.

CONCLUSIONS

After exclusion of any endocrinological reasons for hypoglycemia, differential diagnosis should include NICTH as paraneoplastic syndrome. In rare cases a hematological malignancy may be the underlying disease. The specific treatment of this disease likewise represents the causal treatment of NICTH.

Exclusion of phlebotomine sand flies from inhabited areas by means of vertical mesh barriers

Vector control constitutes an important component of integrated disease control campaigns. Source reduction is not an option for phlebotomine sand fly vectors of leishmaniasis, because larval breeding sites remain either unknown or inaccessible. Thus, all control efforts are directed against the adult sand flies, mostly attempting to limit their contact with humans. We describe experiments using an insecticide-treated vertical barrier to prevent sand flies from reaching inhabited areas of an agricultural settlement. A 400 meter long section of the peripheral fence of Kibbutz Sde Eliyahu, Jordan Valley, Israel was draped with a deltamethrin-impregnated net that is impenetrable to sand flies (polyester net, 450 holes/inch(2)). Sand flies were captured before and after construction of the barrier using CO(2)-baited CDC traps. Sand fly numbers, as monitored around three houses internal to the barrier, exhibited an 84.9% decrease once the barrier was erected (P=0.003). Concurrently, the neighboring control group of three houses, not protected by the barrier, exhibited a 15.9% increase in sand fly numbers (P=0.974). These results corroborate previous findings of field tests conducted on a smaller scale in an arid suburban setting. Campaigns for reducing the burden of sand fly bites and curtailing the transmission of leishmaniasis, should consider integrating vertical fine-mesh nets with other sand fly control measures.

Mechanisms underlying FeCl3-induced arterial thrombosis

BACKGROUND

The FeCl(3)-induced vascular injury model is widely used to study thrombogenesis in vivo, but the processes leading to vascular injury and thrombosis are poorly defined.

OBJECTIVES

The aim of our study was to better characterize the mechanisms of FeCl(3)-induced vascular injury and thrombus formation, in order to evaluate the pathophysiological relevance of this model.

METHODS

FeCl(3) was applied at different concentrations (from 7.5% to 20%) and for different time periods (up to 5 min) to mouse carotid or mesenteric arteries.

RESULTS

Under all the conditions tested, ultrastructural analysis revealed that FeCl(3) diffused through the vessel wall, resulting in endothelial cell denudation without exposure of the inner layers. Hence, only the basement membrane components were exposed to circulating blood cells and might have contributed to thrombus formation. Shortly after FeCl(3) application, numerous ferric ion-filled spherical bodies appeared on the endothelial cells. Interestingly, platelets could adhere to these spheres and form aggregates. Immunogold labeling revealed important amounts of tissue factor at their surface, suggesting that these spheres may play a role in thrombin generation. In vitro experiments indicated that FeCl(3) altered the ability of adhesive proteins, including collagen, fibrinogen and von Willebrand factor, to support platelet adhesion. Finally, real-time intravital microscopy showed no protection against thrombosis in GPVI-immunodepleted and β(1)(-/-) mice, suggesting that GPVI and β(1) integrins, known to be involved in initial platelet adhesion and activation, do not play a critical role in FeCl(3)-induced thrombus formation.

CONCLUSION

This model should be used cautiously, in particular to study the earliest stage of thrombus formation.

Pancreatic graft survival despite partial vascular graft thrombosis due to splenocephalic anastomoses

Thrombotic complications following pancreas transplantation are still the most common cause of nonimmunologic graft loss. The aim of this study was to analyze pancreatic graft function after partial arterial graft thrombosis and the investigation of the pancreatic arterial anatomy with regard to intraparenchymal anastomoses. We retrospectively analyzed the data for 175 consecutive pancreas transplants performed between January 2002 and October 2007. Selective Y-graft angiography was performed in 10 and rubber-milk injection in 5 fresh pancreas specimens. Thrombosis of one leg of the Y-graft was diagnosed in 18 (10.3%) patients. Only one of these patients with thrombosis of the splenic artery required exogenous insulin. Sufficient graft perfusion was demonstrated in all of the remaining grafts. One graft was lost due to acute rejection. In all specimens angiography showed an excellent perfusion of the pancreaticoduodenal arcade, even after selective cannulation of the splenic artery. Arterial collaterals between the gastroduodenal, splenic artery and the superior mesenteric artery were demonstrated. Our results demonstrate that global perfusion of the pancreatic graft and sufficient graft function is sustained after the thrombotic occlusion of one branch of the Y-graft by a complex system of intraparenchymal anastomoses. These anatomical findings may have consequences for resection strategies in pancreas surgery.

Spontaneous mirror symmetry breaking in the aldol reaction and its potential relevance in prebiotic chemistry

The origin of the single chirality of most biomolecules is still a great puzzle. Carbohydrates could form in the formose reaction, which is proposed to be autocatalytic and contains aldol reaction steps. Based on our earlier observation of organoautocatalysis and spontaneous enantioenrichment in absence of deliberate chiral influences in the aldol reaction of acetone and p-nitrobenzaldehyde we suggest that a similar effect might be present also in the aldol reactions involved in gluconeogenesis. Herein we show that reactant precipitation observed in our earlier reported experiments does not affect the asymmetric autocatalysis in the aldol reaction we studied. We explain the phenomenon of spontaneous mirror symmetry breaking in such organocatalytic homogenous systems qualitatively by non-linear reaction network kinetics and classical transition state theory.

Minimizing circulatory arrest by using antegrade cerebral perfusion for aortic arch reconstruction in infants causes fewer postoperative adverse events

BACKGROUND

Because deep hypothermic circulatory arrest (DHCA) carries a risk for neurological damage, antegrade cerebral perfusion (ACP) is used increasingly for aortic arch surgery in infants. We assessed the short-term effects of minimal DHCA (< 30 minutes) versus prolonged DHCA (> 30 minutes) during biventricular aortic arch reconstruction.

METHODS

Twenty-six infants (< 3 months of age) who had undergone aortic arch reconstruction were retrospectively analyzed: 15 infants without DHCA (group A) and 11 infants with DHCA (group B). Group B was further divided into < 30 minutes DHCA (group B1, n = 6), and >or= 30 minutes DHCA (group B2, n = 5). Additionally, minimal DHCA (group A + B1) was compared to prolonged DHCA (group B2).

RESULTS

In the minimal DHCA group (A + B1), 29 % of the patients had a postoperative adverse event, compared to 80 % in the prolonged DHCA group (B2) ( P < 0.05). Average length of stay in hospital was 25 days shorter for the minimal DHCA group (15 days versus 40 days, P < 0.01).

CONCLUSION

Minimal DHCA results in fewer adverse events and a reduced length of stay, compared with prolonged DHCA. Therefore, during aortic arch surgery in infants, DHCA should be minimized by using antegrade cerebral perfusion.

Arterial thrombosis: relevance of a model with two levels of severity assessed by histologic, ultrastructural and functional characterization

BACKGROUND

We previously described a model of laser-induced thrombosis in mesenteric arterioles with superficial and deep levels of injury producing a transient thrombus resolving within 2 min and a larger almost occlusive thrombus, respectively. Both types of lesion were sensitive to platelet GPIIb-IIIa and P2Y(12) inhibition, whereas only deep injuries were sensitive to thrombin blockade.

OBJECTIVE

The aim of the present study was to use histologic methods and electron and intravital microscopy to characterize the lesions and thrombi and to extend our knowledge of the sensitivity of this model to genetic and pharmacologic inhibition.

RESULTS

A superficial injury was found to detach the endothelial cells and expose a collagen III- and IV-rich subendothelium where platelets could adhere. Tissue factor and fibrin were not detected. Deeper penetration of the external elastic lamina occurred in deep injuries, with exposure of collagen I, III and IV. Here the thrombus was composed of platelets exhibiting a decreasing gradient of degranulation from the deepest lesion area to the surface. Fibrin was found close to the most activated platelets. Consistently, glycoprotein VI (GPVI)-collagen and GPIb-von Willebrand factor (VWF) interactions were found to be critical in superficial injuries. After deep lesion, thrombus formation was modestly reduced in GPVI-immunodepleted mice and still strongly inhibited in VWF(-/-) mice. Combined hirudin infusion and GPVI depletion further inhibited thrombosis after deep injury.

CONCLUSIONS

This study confirms the feasibility of inducing arterial thrombosis with distinct levels of severity and establishes the central roles of collagen and VWF in thrombus formation after superficial injury. Collagen, VWF and thrombin all appear to contribute to thrombosis after deep arterial lesion.

[Therapy optimization studies torn between science and funding]

There is no doubt that clinical studies are valuable cornerstones in the development of rational diagnostics and therapy, for the patients' safety, for quality assurance as well as for the development of a body of evidence in medicine. Well recognized multicentric study groups are active in several medical disciplines in Germany. Public funding resources however are miserable as compared to other countries. For example in hematology and oncology funds are almost exclusively available by private foundations as the Deutsche Krebshilfe only. Additionally physicians and institutions who are actively promoting clinical studies have to pay charges for patients' insurance and for registration of studies by the authorities. Furthermore there are increasing difficulties obtaining reimbursement for patients' care in clinical studies. In this context outdated regulations of the German Sozialgesetzbuch V lawbook play an important role. In summary a pronounced reform deficit paired with bureocratic tendencies has become manifested. The most important demands are in this situation: a reliable and realistic regulatory basis for treatment-related clinical studies has to be created. Studies on treatment strategies with registered drugs have to be free from the obligatory patients' insurance which is required for study with non-registered drugs. It has to be clarified that in these studies some regulations of good clinical practice as obligatory external monitoring and source data verification are not feasible and will not be required. The Sozialgesetzbuch V has to be adapted and the actual ban of clinical studies in private practice has to be ended. Treatment related clinical studies have to be free from charges of ethical committees and regulatory authorities. Thereby the financial overload of clinical studies could be reduced and some motivation for further bureocratic proliferation is removed. Finally a longterm, reliable funding resource has to be created independently from the pharmaceutical industry. A possible model could be a foundation for treatment-related studies which is financed by public funds and by funds from the reimbursement companies.