Topology and Function of the S. cerevisiae Autophagy Protein Atg15

The putative phospholipase Atg15 is required for the intravacuolar lysis of autophagic bodies and MVB vesicles. Intracellular membrane lysis is a highly sophisticated mechanism that is not fully understood. The amino-terminal transmembrane domain of Atg15 contains the sorting signal for entry into the MVB pathway. By replacing this domain, we generated chimeras located in the cytosol, the vacuole membrane, and the lumen. The variants at the vacuole membrane and in the lumen were highly active. Together with the absence of Atg15 from the phagophore and autophagic bodies, this suggests that, within the vacuole, Atg15 can lyse vesicles where it is not embedded. In-depth topological analyses showed that Atg15 is a single membrane-spanning protein with the amino-terminus in the cytosol and the rest, including the active site motif, in the ER lumen. Remarkably, only membrane-embedded Atg15 variants affected growth when overexpressed. The growth defects depended on its active site serine 332, showing that it was linked to the enzymatic activity of Atg15. Interestingly, the growth defects were independent of vacuolar proteinase A and vacuolar acidification.

Autophagic and non-autophagic functions of the Saccharomyces cerevisiae PROPPINs Atg18, Atg21 and Hsv2

Atg18, Atg21 and Hsv2 are homologous β-propeller proteins binding to PI3P and PI(3,5)P2. Atg18 is thought to organize lipid transferring protein complexes at contact sites of the growing autophagosome (phagophore) with both the ER and the vacuole. Atg21 is restricted to the vacuole phagophore contact, where it organizes part of the Atg8-lipidation machinery. The role of Hsv2 is less understood, it partly affects micronucleophagy. Atg18 is further involved in regulation of PI(3,5)P2 synthesis. Recently, a novel Atg18-retromer complex and its role in vacuole homeostasis and membrane fission was uncovered.

Vacuole fragmentation depends on a novel Atg18-containing retromer-complex

The yeast PROPPIN Atg18 folds as a β-propeller with two binding sites for phosphatidylinositol-3-phosphate (PtdIns3P) and PtdIns(3,5)P₂ at its circumference. Membrane insertion of an amphipathic loop of Atg18 leads to membrane tubulation and fission. Atg18 has known functions at the PAS during macroautophagy, but the functional relevance of its endosomal and vacuolar pool is not well understood. Here we show in a proximity-dependent labeling approach and by co-immunoprecipitations that Atg18 interacts with Vps35, a central component of the retromer complex. The binding of Atg18 to Vps35 is competitive with the sorting nexin dimer Vps5 and Vps17. This suggests that Atg18 within the retromer can substitute for both the phosphoinositide binding and the membrane bending capabilities of these sorting nexins. Indeed, we found that Atg18-retromer is required for PtdIns(3,5)P₂-dependent vacuolar fragmentation during hyperosmotic stress. The Atg18-retromer is further involved in the normal sorting of the integral membrane protein Atg9. However, PtdIns3P-dependent macroautophagy and the selective cytoplasm-to-vacuole targeting (Cvt) pathway are only partially affected by the Atg18-retromer. We expect that this is due to the plasticity of the different sorting pathways within the endovacuolar system.Abbreviations: BAR: bin/amphiphysin/Rvs; FOA: 5-fluoroorotic acid; PAS: phagophore assembly site; PROPPIN: beta-propeller that binds phosphoinositides; PtdIns3P: phosphatidylinositol-3-phosphate; PX: phox homology.

Superior Properties of Fc-comprising scTRAIL Fusion Proteins

The TNF-related apoptosis-inducing ligand (TRAIL) has been considered as a promising molecule for cancer treatment. However, clinical studies with soluble TRAIL failed to show therapeutic activity, which resulted in subsequent development of more potent TRAIL-based therapeutics. In this study, we applied defined oligomerization and tumor targeting as strategies to further improve the activity of a single-chain version of TRAIL (scTRAIL). We compared three different formats of EGF receptor (EGFR)-targeting dimeric scTRAIL fusion proteins [Diabody (Db)-scTRAIL, scFv-IgE heavy chain domain 2 (EHD2)-scTRAIL, scFv-Fc-scTRAIL] as well as two nontargeted dimeric scTRAIL molecules (EHD2-scTRAIL, Fc-scTRAIL) to reveal the influence of targeting and protein format on antitumor activity. All EGFR-targeted dimeric scTRAIL molecules showed similar binding properties and comparable cell death induction in vitro, exceeding the activity of the respective nontargeted dimeric format and monomeric scTRAIL. Superior properties were observed for the Fc fusion proteins with respect to production and in vivo half-life. In vivo studies using a Colo205 xenograft model revealed potent antitumor activity of all EGFR-targeting formats and Fc-scTRAIL and furthermore highlighted the higher efficacy of fusion proteins comprising an Fc part. Despite enhanced in vitro cell death induction of targeted scTRAIL molecules, however, comparable antitumor activities were found for the EGFR-targeting scFv-Fc-scTRAIL and the nontargeting Fc-scTRAIL in vivoMol Cancer Ther; 16(12); 2792-802. ©2017 AACR.

Health status and disease burden of unaccompanied asylum-seeking adolescents in Bielefeld, Germany: cross-sectional pilot study

OBJECTIVE

This exploratory pilot study aimed to investigate the physical and mental disease burden of unaccompanied asylum-seeking adolescents arriving in Bielefeld, a medium-size city in Germany.

METHODS

A cross-sectional survey with purposive sampling of 102 unaccompanied asylum-seeking adolescents aged 12-18 years was performed. Information on general health status, selected infectious and non-communicable diseases, iron deficiency anaemia and mental illness was collected during routine check-up medical examinations upon arrival in Bielefeld, Germany. The data were analysed using descriptive statistics.

RESULTS

The analysis revealed a complex disease burden with a high prevalence of infections (58.8%), mental illness (13.7%) and iron deficiency anaemia (17.6%) and a very low prevalence of non-communicable diseases (<2.0%). One in five of the refugees were infected with parasites. Whilst sub-Saharan Africans showed the highest prevalence of infections (86.7%), including highest prevalences of parasites (46.7%), West Asians had the highest prevalence of mental disorders (20.0%). Overall, the disease burden in females was higher.

CONCLUSION

A thorough medical and psychological screening after arrival is highly recommended to reduce the individual disease burden and the risk of infection for others. This promotes good physical and mental health, which is needed for successful integration into the receiving society. Barriers to health service access for unaccompanied asylum-seeking adolescents need to be lowered to allow need-specific health care and prevention.

Acute Cerebrovascular Disease in the Young

Background and Purpose—

Strokes have especially devastating implications if they occur early in life; however, only limited information exists on the characteristics of acute cerebrovascular disease in young adults. Although risk factors and manifestation of atherosclerosis are commonly associated with stroke in the elderly, recent data suggests different causes for stroke in the young. We initiated the prospective, multinational European study Stroke in Young Fabry Patients (sifap) to characterize a cohort of young stroke patients.

Methods—

Overall, 5023 patients aged 18 to 55 years with the diagnosis of ischemic stroke (3396), hemorrhagic stroke (271), transient ischemic attack (1071) were enrolled in 15 European countries and 47 centers between April 2007 and January 2010 undergoing a detailed, standardized, clinical, laboratory, and radiological protocol.

Results—

Median age in the overall cohort was 46 years. Definite Fabry disease was diagnosed in 0.5% (95% confidence interval, 0.4%–0.8%; n=27) of all patients; and probable Fabry disease in additional 18 patients. Males dominated the study population (2962/59%) whereas females outnumbered men (65.3%) among the youngest patients (18–24 years). About 80.5% of the patients had a first stroke. Silent infarcts on magnetic resonance imaging were seen in 20% of patients with a first-ever stroke, and in 11.4% of patients with transient ischemic attack and no history of a previous cerebrovascular event. The most common causes of ischemic stroke were large artery atherosclerosis (18.6%) and dissection (9.9%).

Conclusions—

Definite Fabry disease occurs in 0.5% and probable Fabry disease in further 0.4% of young stroke patients. Silent infarcts, white matter intensities, and classical risk factors were highly prevalent, emphasizing the need for new early preventive strategies.

Clinical Trial Registration Information—

URL: http://www.clinicaltrials.gov .Unique identifier: NCT00414583

Hemodynamic alterations in vertebrobasilar large artery disease assessed by arterial spin-labeling MR imaging

BACKGROUND AND PURPOSE

VB artery stenosis is associated with a high risk of recurrent ischemic events, and knowledge about the hemodynamic relevance of VB stenosis is important for clinical decision making. In this study, multiple inflow pulsed ASL MR imaging was assessed for its ability to measure CBF and ATT in patients with VB disease.

MATERIALS AND METHODS

ASL was performed on a 3T MR imaging scanner in 41 participants. Twenty-one patients had a history of ischemic events in the VB circulation (14 men, 7 women, age 66 ± 11 years). Clinical data and CE-MRA were used to classify VB disease severity. Twenty age-matched adults were controls. Group and within-VB analyses were performed. Mean CBF and ATT values in the ROIs were adjusted by excluding voxels that did not produce a reliable ASL estimate.

RESULTS

CBF was reduced (P < .003) in patients compared with controls, which was significant after excluding voxels with a poor fit. Differences in ATT between patients and controls were not significant after voxel correction. There was a strong correlation between CBF and ATT among patients. Finally, ATT was significantly correlated with VB disease severity (P = .026).

CONCLUSIONS

Multiple inflow ASL distinguished patients with VB disease from age matched-controls. VB disease rating was associated with prolonged ATT downstream. ASL may have diagnostic potential among patients in whom risk of intervention is high.

Population-based study of risk and predictors of stroke in the first few hours after a TIA

BACKGROUND

Several recent guidelines recommend assessment of patients with TIA within 24 hours, but it is uncertain how many recurrent strokes occur within 24 hours. It is also unclear whether the ABCD2 risk score reliably identifies recurrences in the first few hours.

METHODS

In a prospective, population-based incidence study of TIA and stroke with complete follow-up (Oxford Vascular Study), we determined the 6-, 12-, and 24-hour risks of recurrent stroke, defined as new neurologic symptoms of sudden onset after initial recovery.

RESULTS

Of 1,247 first TIA or strokes, 35 had recurrent strokes within 24 hours, all in the same arterial territory. The initial event had recovered prior to the recurrent stroke (i.e., was a TIA) in 25 cases. The 6-, 12-, and 24-hour stroke risks after 488 first TIAs were 1.2% (95% confidence interval [CI]: 0.2-2.2), 2.1% (0.8-3.2), and 5.1% (3.1-7.1), with 42% of all strokes during the 30 days after a first TIA occurring within the first 24 hours. The 12- and 24-hour risks were strongly related to ABCD2 score (p = 0.02 and p = 0.0003). Sixteen (64%) of the 25 cases sought urgent medical attention prior to the recurrent stroke, but none received antiplatelet treatment acutely.

CONCLUSION

That about half of all recurrent strokes during the 7 days after a TIA occur in the first 24 hours highlights the need for emergency assessment. That the ABCD2 score is reliable in the hyperacute phase shows that appropriately triaged emergency assessment and treatment are feasible.

Intrakranielle Blutung bei erworbener Hemmkörperhämophilie

Acquired hemophilia is a rare complication in autoimmune disorders and malignancies. It can result in bleedings into skin and muscle, whereas intracranial hemorrhage in adults has so far not been described. We report a patient with acute intracerebral hemorrhage due to acquired hemophilia with factor VIII inhibition. The patient was treated with recombinant factor VIIa and open hematoma evacuation followed by administration of cortisone and cyclophosphamide. After good initial recovery, intracerebral rebleeding occurred and the patient died from brainstem compression.

Isolated diffuse hemangiomatosis of the spleen: case report and review of literature

Small localized hemangiomas are common neoplasms of the spleen. Isolated diffuse splenic hemangiomatosis, however, is very rare. This lesion can be accompanied by severe hypersplenism and other complications. We report on a case with significant splenomegaly caused by diffuse hemangiomatosis, which was an incidental finding without any clinical disorders. After splenectomy, the normal parenchyma was found to be widely replaced by multiple spongy nodules. Histologically, cavernous vessels were distributed throughout the whole organ, with endothelial cells expressing vimentin, factor VIII and CD 31, but not CD8. Splenic sinus lining cells exhibited a strongly positive reaction with CD8, which became faint and disrupted in highly dilated sinuses in the vicinity of cavernous vessels. In some areas, there seemed to be a gradual transition from cystically dilated splenic sinuses to cavernous vessels. The differential diagnosis must consider other splenic vascular tumors, such as littoral cell angioma, lymphangioma, peliosis of the spleen, and hamartoma. The pathogenesis of diffuse splenic hemangiomatosis is controversial, and a malformative or neoplastic origin is under debate. A derivation from splenic sinusoidal cells was suggested by some authors, but was rejected by others. Our findings cannot exclude a neoplastic origin from splenic sinuses but, finally, the etiology and pathogenesis of this vascular lesion remain uncertain.

Green tea extract and its polyphenols markedly inhibit luminol-dependent chemiluminescence activated by peroxynitrite or SIN-1

This study is based on a simple chemical interaction of peroxynitrite (OONO-) and luminol, which produces blue light upon oxidation. Since peroxynitrite has a half-life of less than 1 s, a drug known as SIN-1 is used as a peroxynitrite generator. In addition peroxynitrite itself was used directly with a fast injection-mixing system to ascertain whether there are differences between it and the peroxynitrite-generating system (SIN-1) which mimics the natural production of (OONO-). Peroxynitrite is a potent oxidizing compound (1000 times more active than equidose hydrogen peroxide) and it can oxidize carbohydrates, lipids, proteins and nucleic acids. Upon stimulation by inflammation and/or infection, macrophages and neutrophils can be activated to produce large amounts of peroxynitrite. We are interested in simple chemicals that are non-toxic that could inhibit or destroy peroxynitrite, which might otherwise cause inappropriate damage to blood and tissues. Green tea is a complex mixture containing several potent major antioxidant constituents, eg flavins and/or polyphenols. The constituents in green tea may react directly or indirectly with peroxynitrite or its constituents through the process of antioxidation to inhibit light. Alternatively, compounds could produce superoxide which, when reacted with nitric oxide, could produce more peroxynitrite and hence more light with luminol. Therefore, as the tea or antioxidants from tea are diluted, while the peroxynitrite or its precursors are kept at a constant concentration, one can observe unusual behaviour regarding light emission. Initially, at high doses of tea or antioxidant, one observes clear inhibition of the light generated from the reaction of peroxynitrite and luminol. However, at dilute concentrations of antioxidants, one can often observe stimulation of light. Possible reasons for these observations are discussed.