Comparison of the hemoglobin variability in non-chronic kidney disease or end-stage renal disease participants and patients with CKD and ESRD.

INTRODUCTION: Hemoglobin (Hb) variability occurs frequently in hemodialysis (HD) patients during erythropoietin (EPO) therapy. Guidelines define a narrow target range for the anemia treatment in these patients that is difficult to adhere to in practice. Our aim was to evaluate whether the Hb variability in HD patients is higher compared to non-chronic kidney disease or end-stage renal disease (ESRD) participants and patients with CKD stage I or II. MATERIALS AND METHODS: Monthly blood samples were assessed prospectively in 100 non-CKD or ESRD participants and 57 patients with CKD stage I or II, and retrospectively in 74 HD patients without changes in EPO or iron dose for 6 months. Variability was calculated and compared between the different groups. RESULTS: Hb variability was significantly higher in HD patients compared to the other groups, corresponding to results of previous studies. There were no significant differences between non-CKD or ESRD participants and patients with CKD stage I or II in terms of standard deviation (SD), residual SD, fluctuations across threshold, Hb cycling, and mean absolute change of Hb every 30 days (p > 0.05), but a significant difference compared to HD patients (p < 0.001). There were no significant differences between the groups in time in target and area under the curve (AUC) (p > 0.05). CONCLUSION: Hb variability is a common phenomenon in all groups independently of the method used for assessment and even without EPO therapy. The target range is difficult to achieve for HD patients and should be reconsidered in the future to avoid unsettling both the patients and the staff.

Evaluation of dried blood spots as alternative sampling material for serological detection of anti-SARS-CoV-2 antibodies using established ELISAs.

OBJECTIVES: During the current pandemic, antibody testing based on venous serum helps to determine whether the tested person has been previously infected with SARS-CoV-2. Alternatively, capillary blood can be taken via a finger prick (dried blood spots, DBS). In this study, paired DBS and venipuncture samples were tested using two serological assays to evaluate the usability of DBS for the detection of anti-SARS-CoV-2 antibodies. METHODS: Paired samples of DBS and venous serum were collected from 389 volunteers, of whom 75 had a recent PCR-confirmed SARS-CoV-2 infection, and tested for anti-SARS-CoV-2 IgG antibodies against both viral S1 and nucleocapsid protein (NCP) antigens using two ELISAs. Degree of agreement and correlation coefficients between ELISA results based on the two sampling methods were calculated. RESULTS: Results of DBS showed almost perfect agreement and high correlations with results from corresponding serum samples in both the S1-based ELISA and the NCP-based ELISA. CONCLUSIONS: ELISA results derived from DBS showed very high agreement to those obtained with serum, supposing adequate usability and robustness of DBS as sample material for detection of anti-SARS-CoV-2 antibodies. In the near future, large-scale epidemiological screening for antibodies against SARS-CoV-2 will be carried out. Since DBS reduce the strain on healthcare institutions regarding sample collection, they have a potential to facilitate efficient community- and population-based screening in the current SARS-CoV-2 pandemic.

Inhibition of autophagy through MAPK14-mediated phosphorylation of ATG5.

Autophagy is a catabolic mechanism that is important for many biological processes such as cell homeostasis, development and immunity. Though many molecular components of the autophagy pathway have been identified, the signaling pathways regulating the activity of essential autophagy mediators are still poorly defined. We recently demonstrated that the mitogen-activated protein kinase MAPK14 (p38α), when activated by the GADD45B (Gadd45ß)-MAP3K4 (MEKK4) signaling complex (but not other MAPK14 activators), is directed to autophagosomes. Therefore, we demonstrated for the first time that MAPK14 operates at this subcellular compartment. Importantly, activation of MAPK14 impairs autophagosome-lysosome fusion and, thus, autophagy. This was demonstrated by increased autophagic flux in MAPK14-deficient as well as in GADD45B-deficient cells. Moreover, we identified a novel post-translational modification of the crucial autophagy mediator ATG5, since MAPK14 directly phosphorylates ATG5 at threonine 75, which is evolutionarily conserved from yeast to human. Using ATG5-deficient cells, which we reconstituted with either a phosphorylation-defective or a phospho-mimetic mutant of ATG5, we demonstrated that phosphorylation of ATG5 results in impaired autophagy.

Transcript profiling reveals new insights into the acclimation of the mesophilic fresh-water cyanobacterium Synechococcus elongatus PCC 7942 to iron starvation.

The regulatory network for acclimation of the obligate photoautotrophic fresh water cyanobacterium Synechococcus elongatus PCC 7942 to iron (Fe) limitation was studied by transcript profiling with an oligonucleotide whole genome DNA microarray. Six regions on the chromosome with several Fe-regulated genes each were identified. The irpAB and fut region encode putative Fe uptake systems, the suf region participates in [Fe-sulfur] cluster assembly under oxidative stress and Fe limitation, the isiAB region encodes CP43' and flavodoxin, the idiCB region encodes the NuoE-like electron transport associated protein IdiC and the transcriptional activator IdiB, and the ackA/pgam region encodes an acetate kinase and a phosphoglycerate mutase. We also investigated the response of two S. elongatus PCC 7942 mutants to Fe starvation. These were mutant K10, lacking IdiB but containing IdiC, and mutant MuD, representing a idiC-merodiploid mutant with a strongly reduced amount of IdiC as well as IdiB. The absence of IdiB in mutant K10 or the strongly reduced amount of IdiB in mutant MuD allowed for the identification of additional members of the Fe-responsive IdiB regulon. Besides idiA and the irpAB operon somB(1), somA(2), ftr1, ackA, pgam, and nat also seem to be regulated by IdiB. In addition to the reduced amount of IdiB in MuD, the low concentration of IdiC may be responsible for a number of additional changes in the abundance of mainly photosynthesis-related transcripts as compared to the wild type and mutant K10. This fact may explain why it has been impossible to obtain a fully segregated IdiC-free mutant, whereas it was possible to obtain a fully segregated IdiB-free mutant.