The impact of obesity on the outcome of severe SARS-CoV-2 ARDS in a high volume ECMO centre: ECMO and corticosteroids support the obesity paradox.

PURPOSE: The aim was to verify the impact of obesity on the long-term outcome of patients with severe SARS-CoV-2 ARDS. MATERIALS AND METHODS: The retrospective study included patients admitted to the high-volume ECMO centre between March 2020 and March 2022. The impact of body mass index (BMI), co-morbidities and therapeutic measures on the short and 90-day outcomes was analysed. RESULTS: 292 patients were included, of whom 119(40.8%) were treated with veno-venous ECMO cannulated mostly (73%) in a local hospital. 58.5% were obese (64.7% on ECMO), the ECMO was most frequent in BMI > 40(49%). The ICU mortality (36.8% for obese vs 33.9% for the non-obese, p = 0.58) was related to ECMO only for the non-obese (p = 0.04). The 90-day mortalities (48.5% obese vs 45.5% non-obese, p = 0.603) of the ECMO and non-ECMO patients were not significantly influenced by BMI (p = 0.47, p = 0.771, respectively). The obesity associated risk factors for adverse outcome were age <50 (RR 2.14) and history of chronic immunosuppressive therapy (RR 2.11, p = 0.009). The higher dosage of steroids (RR 0.57, p = 0.05) associated with a better outcome. CONCLUSIONS: The high incidence of obesity was not associated with worse short and long-term outcomes. ECMO in obese patients together with the use of steroids in the later stage of ARDS may improve survival.

Ensuring the safety of vaccine cell substrates by massively parallel sequencing of the transcriptome.

Massively parallel, deep, sequencing of the transcriptome coupled with algorithmic analysis to identify adventitious agents (MP-Seq™) is an important adjunct in ensuring the safety of cells used in vaccine production. Such cells may harbour novel viruses whose sequences are unknown or latent viruses that are only expressed following stress to the cells. MP-Seq is an unbiased and comprehensive method to identify such viruses and other adventitious agents without prior knowledge of the nature of those agents. Here we demonstrate its utility as part of an integrated approach to identify and characterise potential contaminants within commonly used virus and vaccine production cell lines. Through this analysis, in combination with more traditional approaches, we have excluded the presence of porcine circoviruses in the ATCC Vero cell bank (CCL-81), however, we found that a full length betaretrovirus related to SRV can be expressed in these cells, a factor that may be of importance in the production of certain vaccines. Similarly, insect cells are proving to be valuable for the production of virus like particles and sub-unit vaccines, but they can harbour a range of latent viruses. We show that following MP-Seq of the Trichoplusia ni (High Five cell line) transcriptome we were able to detect a contaminating, latent nodavirus and identify an expressed errantivirus genome. Collectively, these studies have reinforced the role of MP-Seq as an integral tool for the identification of contaminating agents in vaccine cell substrates.

Burden of antimicrobial resistance in European hospitals: excess mortality and length of hospital stay associated with bloodstream infections due to Escherichia coli resistant to third-generation cephalosporins.

OBJECTIVES: This study determined excess mortality and length of hospital stay (LOS) attributable to bloodstream infection (BSI) caused by third-generation-cephalosporin-resistant Escherichia coli in Europe. METHODS: A prospective parallel matched cohort design was used. Cohort I consisted of patients with third-generation-cephalosporin-resistant E. coli BSI (REC) and cohort II consisted of patients with third-generation-cephalosporin-susceptible E. coli BSI (SEC). Patients in both cohorts were matched for LOS before infection with patients free of the respective BSI. Thirteen European tertiary care centres participated between July 2007 and June 2008. RESULTS: Cohort I consisted of 111 REC patients and 204 controls and cohort II consisted of 1110 SEC patients and 2084 controls. REC patients had a higher mortality at 30 days (adjusted odds ratio = 4.6) and a higher hospital mortality (adjusted hazard ratio = 5.7) than their controls. LOS was increased by 8 days. For SEC patients, these figures were adjusted odds ratio = 1.9, adjusted hazard ratio = 2.0 and excess LOS = 3 days. A 2.5 times [95% confidence interval (95% CI) 0.9-6.8] increase in all-cause mortality at 30 days and a 2.9 times (95% CI 1.2-6.9) increase in mortality during entire hospital stay as well as an excess LOS of 5 days (95% CI 0.4-10.2) could be attributed to resistance to third-generation cephalosporins in E. coli BSI. CONCLUSIONS: Morbidity and mortality attributable to third-generation-cephalosporin-resistant E. coli BSI is significant. If prevailing resistance trends continue, high societal and economic costs can be expected. Better management of infections caused by resistant E. coli is becoming essential.

Massively parallel sequencing for the detection of adventitious viruses.

CONFERENCE PROCEEDING Proceedings of the PDA/FDA Adventitious Viruses in Biologics: Detection and Mitigation Strategies Workshop in Bethesda, MD, USA; December 1-3, 2010 Guest Editors: Arifa Khan (Bethesda, MD), Patricia Hughes (Bethesda, MD) and Michael Wiebe (San Francisco, CA) The rate at which unknown adventitious agents are being discovered is accelerating. The ability to mitigate this risk begins with detection. Several molecular technologies for the detection of adventitious agent genomic signatures are reviewed here. Massively parallel sequencing (MP-Seq) is distinguished by its breadth of coverage. Supported by trained virologists and as part of a quality system, MP-Seq can be an early detection method for safe production of biologics.

A case of OXA-48 carbapenemase-producing Klebsiella pneumoniae in a patient transferred to Slovenia from Libya, November 2011.

We report the first documented case of OXA-48-producing Klebsiella pneumoniae in Slovenia isolated from rectal surveillance cultures from a patient transferred from Libya. The patient was colonised with both ESBL-producing Escherichia coli and ESBL- and OXA-48-producing K. pneumoniae. Three further patients were colonised with ESBL-producing E. coli. This underscores the importance of an early warning system on European level and screening upon admission of patients transferred across borders and between healthcare systems.

Characterisation of invasive Haemophilus influenzae isolates in Slovenia, 1993-2008.

The objectives of our study were to describe the epidemiology of invasive Haemophilus influenzae disease from 1993 to 2008 in Slovenia, a country with routine H. influenzae serotype b (Hib) conjugate vaccination since the year 2000. A total of 292 isolates of H. influenzae, recovered from a normally sterile site, were collected in the study period. The isolates were serotyped by slide agglutination and antibiotic susceptibility was determined. One hundred and eight isolates received after the year 2000 were serotyped by slide agglutination and by polymerase chain reaction (PCR) capsule typing, and both methods were compared. After the introduction of the routine Hib vaccination, the incidence of H. influenzae disease in children under the age of 5 years has decreased by 87.6% and type b was replaced by non-typeable H. influenzae as the predominant serotype. The proportion of serotype b decreased from 85.3% in the pre-vaccination period to 13.0% in the vaccination period and the proportion of non-capsulated isolates increased from 12.0 to 85.2%. The study of genetic relatedness by pulsed-field gel electrophoresis (PFGE) demonstrated that the isolates of serotypes b and f were genetically homogeneous within the serotype. The results of our national surveillance showed that the vaccine has been very efficient in preventing Hib invasive disease in Slovenia. Nevertheless, we see a need for further monitoring of invasive H. influenzae infections at a national level.

Ethics and methods in surgical trials.

This paper focuses on invasive therapeutic procedures, defined as procedures requiring the introduction of hands, instruments, or devices into the body via incisions or punctures of the skin or mucous membranes performed with the intent of changing the natural history of a human disease or condition for the better. Ethical and methodological concerns have been expressed about studies designed to evaluate the effects of invasive therapeutic procedures. Can such studies meet the same standards demanded of those, for example, evaluating pharmaceutical agents? This paper describes a research project aimed at examining the interplay and sometimes apparent conflict between ethical standards for human research and standards for methodological rigor in trials of invasive procedures. The paper discusses how the authors plan to develop a set of consensus standards that, if met, would result in substantial and much-needed improvements in the methodological and ethical quality of such trials.

[Osteosynthesis of intracapsular femoral neck fractures by dynamic hip screw (DHS) fixation]. / Osteosyntéza intrakapsulárních zlomenin krcku stehenní kosti metodou DHS.

PURPOSE OF THE STUDY: The treatment of femoral neck fractures shows a relatively high number of poor outcomes, usually due to late complications, such as avascular necrosis of the femoral head or pseudoarthrosis. The latter may develop when the osteosynthesis of osteoporotic bone fails. The aim of this retrospective study was to evaluate a group of patients treated by osteo- synthesis for intra-capsular femoral neck fractures at our department, and to verify indication criteria and identify the therapeutic procedures that are best suited to our conditions. MATERIAL: In the 1997-2001 period, a total of 81 patients with intra-capsular femoral neck fractures were operated on. Of these, 64 treated by dynamic hip screw (DHS) fixation were followed up for at least 5 years. There were 33 women and 31 men; the average age was 21.5 years (range, 21 to 74 years). METHODS: The Garden classification was used to evaluate the displacement of femoral neck fractures. Preferably, osteosynthesis was carried out by closed reduction; only exceptionally was an extension device for the operating table used. A 135-degree sliding hip screw, with a short thread, directed to the head centre and a two-hole side plate were used most often.The average follow-up was 6.9 years. Evaluated were: the occurrence of late complications in relation to the length of time between injury and surgery, quality of fracture reduction, use of an anti-rotation screw and necessity of repeat surgery. RESULTS: Garden I or II fractures were diagnosed in 13 patients, 51 had Garden III or Garden IV fractures. Bone union without complications was achieved in 73.4 % of the patients within 12 months of surgery. Late complications were found in 26.6 %; of these, only one had Garden I fracture and the rest were Garden III and IV fractures. An anti-rotation screw was used in 39 patients (60.9 %) and its use had no effect on the development of late complications. Of the seven patients who developed pseudoarthrosis, the screw was used in four (57.1%); out of the nine patients with avascular necrosis, it was used in six (66.7 %). In the whole group, an unsatisfactory outcome of post-operative reduction was recorded in 29.7 %. In the patients with late complications this was found in 52.9 %, which was a statistically significant difference. Of the 17 patients with poor outcomes, 14 underwent total hip arthroplasty; in the patients with necrosis, arthroplasty was carried out at an average of 26 months post-operatively, in those with pseudoarthrosis it was at 7 months post-operatively. DISCUSSION: For the treatment of intra-capsular fractures of the femoral neck, surgery is the most frequent approach, but there are controversial views on various relevant issues. An important factor affecting the treatment outcome is the patient's bone quality. CONCLUSIONS: Our results show a direct relationship between the extent of fracture displacement and late complications, i.e., avascular necrosis and non-union. The quality of fracture reduction had a greater effect on fracture non-union than on the development of femoral head necrosis. The length of time between injury and surgery played a lesser role than it is believed. The use of an anti-rotation screw was not significantly related to the occurrence of late complications. The DHS method is economical and available, and provided sufficient results whose comparisons with the literature data show that this therapeutic approach is correct.

[Total endoprosthesis replacement after hip joint arthrodesis]. / Totální endoprotéza po artrodéze kycelního kloubu.

PURPOSE OF THE STUDY: To evaluate mid-term results of conversion of arthrodesis to total hip replacement in terms of X-ray findings and benefits for the patient. MATERIAL: Ten patients who had undergone hip joint arthrodesis were clinically examined and X-rayed and the findings evaluated. The most common indications for arthrodesis were posttraumatic lesions or the sequelae of a dysplastic hip joint, Perthes disease and inflammatory hip arthritis. The average age was 24.6 years (range, 15-37) at the first operation (arthrodesis) and 42.5 years (range, 30-61) at the second operation (hip arthroplasty). The average follow-up was 9.3 years (range, 1-16). Patients with true ankylosis of the hip joint were not included. METHODS: The patients were clinically examined for the range of motion, which was evaluated by Harris hip scores and X-ray findings. RESULTS: All eight patients who underwent total hip replacement due to persistent pain in the lumbosacral region experienced pain relief or its absence. This also applied to the patients whose X-ray films showed signs of spondylarthritis. The Harris hip scores showed that six patients were able to walk to longer distances without any support. No radiographic evidence of acetabular component loosening was found. One patient had to undergo reimplantation of the femoral component because of aseptic loosening. In the early postoperative period, one dislocation of the prosthesis and one sciatic nerve injury resulting in transient paresis of the peroneal nerve were recorded. None of the complications required repeat surgery. All patients reported that they would undergo the procedure again despite an increased risk associated with this procedure. DISCUSSION: Our results are in agreement with similar findings in this field. We did not find an increase in failed hip arthroplasty in older patients. The X-ray findings were very satisfactory, particularly those concerning the acetabular component. Patients who had true ankylosis of the hip joint were not included in the study. The average range of motion achieved in our patients corresponds to that reported in the literature. CONCLUSIONS: Conversion of hip arthrodesis to total hip replacement is not a frequent surgical procedure. It is associated with a higher degree of risk because of changed anatomy due to previous surgical interventions in that region. Motion restoration in the hip joint results in reducing low back pain and, consequently, improving the quality of life. All evaluated patients would be willing to undergo the operation again.

Activity of telithromycin and seven other agents against 1034 pediatric Streptococcus pneumoniae isolates from ten central and eastern European centers.

OBJECTIVE: To test the activity of telithromycin against 1034 Streptococcus pneumoniae isolates from pediatric patients in ten centers from ten central and eastern European countries during 2000-2001, and to compare it with the activities of erythromycin A, azithromycin, clarithromycin, clindamycin, and quinupristin-dalfopristin. METHODS: The minimum inhibitory concentrations (MICs) of telithromycin, erythromycin A, azithromycin, clarithromycin, clindamycin, levofloxacin, quinupristin-dalfopristin and penicillin G were tested by the agar dilution method with incubation in air, and mechanisms of resistance to macrolides and quinolones were investigated. RESULTS: Strains were isolated from sputum, tracheal aspirates, ear, eye, blood, and cerebrospinal fluid. Among S. pneumoniae strains tested, 36% had raised penicillin G MICs (>/= 0.12 mg/L). Susceptibilities were as follows: telithromycin, quinupristin-dalfopristin and levofloxacin, >/= 99%; clindamycin, 83%; and erythromycin A, azithromycin and clarithromycin, 78%. Of 230 (22.3%) erythromycin A-resistant S. pneumoniae strains, 176 (79.6%) had erm(B), 38 (16.1%) had mef(A), and 10 (4.3%) had mutations in 23S ribosomal RNA or in ribosomal protein L4. The rates of drug-resistant S. pneumoniae are high in all centers except Kaunas, Riga, and Prague. CONCLUSION: Telithromycin had low MICs against all strains, irrespective of macrolide, azalide or clindamycin resistance. Ribosomal methylation was the most prevalent resistance mechanism among all resistant strains, except in Sofia, where the prevalence of the efflux mechanism was higher.

Activity of telithromycin compared with seven other agents against 1039 Streptococcus pyogenes pediatric isolates from ten centers in central and eastern Europe.

In total, 1039 pediatric Streptococcus pyogenes isolates from Bulgaria, Croatia, the Czech Republic, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia and Slovenia were studied. All strains were susceptible to penicillin G, levofloxacin, and quinupristin-dalfopristin, 91-100% to telithromycin, and 82-100% to erythromycin, azithromycin, and clarithromycin, and 90-100% to clindamycin. Macrolide resistance occurred mainly in Slovakia (25%), the Czech Republic (17.3%), and Croatia (15.8%). Overall, 9.7% of S. pyogenes isolates were erythromycin resistant due to erm(B)- or erm(A)-encoded methylases (72.3%) or to a mef(A)-encoded efflux pump (25.7%). One strain had alterations of both 23S rRNA (A2058G Escherichia coli numbering) and ribosomal protein L22 (G95D).

Role of alpha9 nicotinic ACh receptor subunits in the development and function of cochlear efferent innervation.

Cochlear outer hair cells (OHCs) express alpha9 nACh receptors and are contacted by descending, predominately cholinergic, efferent fibers originating in the CNS. Mice carrying a null mutation for the nACh alpha9 gene were produced to investigate its role(s) in auditory processing and development of hair cell innervation. In alpha9 knockout mice, most OHCs were innervated by one large terminal instead of multiple smaller terminals as in wild types, suggesting a role for the nACh alpha9 subunit in development of mature synaptic connections. Alpha9 knockout mice also failed to show suppression of cochlear responses (compound action potentials, distortion product otoacoustic emissions) during efferent fiber activation, demonstrating the key role alpha9 receptors play in mediating the only known effects of the olivocochlear system.

[Maisonneuve fracture.]. / Maisonneuveova zlomenina.

Nineteen patients with acute Maisonneuve fracture of ankle were treated at the Orthopaedic Clinic IPVZ FN Bulovka in 1993-1997. This number represets 5 % of all patients treated acutely for fracturedislocation of ankle. Another 5 patients were managed for poor results of the management of this fracture treated at other Clinic. In all patients surgical therapy was indicated: 14 times - the method of insertion of two parallel transfixation (positioning) screws, 5 times - the method of insertion of 1 screw combined with plaster cast fixation. In patients with the resulting poor outcomes after the fracture, reconstruction was performed in 1 case and in case of ankle fusion 4 times. The follow-up covered 10 patients after acute operation, of which in 7 patients the result was exellent, in 1 patient good and 2 patients evaluate the condition as satifactory. On this basis it may be concluded that surgical therapy in the shortest possible interval after the trauma with the use of 2 transfixation (positioning) screws and fixation of medial melleolus or by suture of deltoid ligament is fully indicated. In case of contrasindication of surgical treatment a high cast has to be applied extending above the knee in the internal rotation of the lower limb. Key words: Maisonneuve fracture, fracture-dislocation of ankle, therapy, diagnosis.

Genetic dissection of a mammalian replicator in the human beta-globin locus.

The timing and localization of DNA replication initiation in mammalian cells are heritable traits, but it is not known whether initiation requires specific DNA sequences. A site-specific recombination strategy was used to show that DNA sequences previously identified as replication initiation sites could initiate replication when transferred to new chromosomal locations. An 8-kilobase DNA sequence encompassing the origin of DNA replication in the human beta-globin locus initiated replication in the simian genome. Specific deletions within the globin origin did not initiate replication in these chromosomal sites. These data suggest that initiation of DNA replication in mammalian cells requires specific sequence information and extend the replicon hypothesis to higher eukaryotes.

Late gene expression from the Epstein-Barr virus BcLF1 and BFRF3 promoters does not require DNA replication in cis.

Late gene expression follows and is dependent upon lytic replication of the viral genome. Although experimental evidence is lacking, lytic viral DNA replication is believed to remove modifications or binding factors from the genome which serve to repress late gene expression during latency or the early lytic cycle. We have developed a reporter assay to begin characterizing the mechanisms that regulate late gene expression in Epstein-Barr virus (EBV). In this model system, the activities of late promoter-reporter fusions are measured following transient transfection into tissue culture cells expressing EBV during different stages of the lytic cycle. This system faithfully recapitulates late expression patterns from the endogenous virus, implicating specific cis-active sequences in the control of late gene expression. In addition, these promoters respond only indirectly to the viral immediate-early transactivator, ZEBRA. This indirect response is mediated by other viral or virally induced activities downstream of ZEBRA in the lytic cascade. In this system, late gene expression is sensitive to inhibitors of the viral DNA polymerase such as phosphonoacetic acid, although the reporters lack a eukaryotic origin of replication and are not replicated under the assay conditions. Thus, replication of the transcriptional template is not a prerequisite for expression with late kinetics, a finding inconsistent with the current models which posit a cis-active relationship between lytic EBV DNA replication and late gene expression. Rather, analysis of this system has revealed a trans relationship between late gene expression and viral DNA replication and highlights the indirect and complex link between these two events.

[Chronic tibialis anterior syndrome.]. / Chronický tibialis anterior syndrom.

Chronic tibialis anterior syndrome affects most frequently adolescent sportsmen. It is manifested by pain on the anterior side of the leg and sometimes also by claudications after burdening. The cause is hypertrophy of the m. tibialis anterior which leads to increased subfascial pressure and thus development of the syndrome. The diagnosis is frequently incorrect and the condition is treated as periostitis or enthesopathy. As the cause is increased subfascial pressure after burdening, causal treatment is fasciotomy of the anterior compartment of the leg. The authors present a case of bilateral syndrome in a female canoeist operated at the age of 19 years. Key words: chronic tibialis anterior syndrome, chronic compartment syndrome, compartment syndrome.

Two 21-kilodalton components of the Epstein-Barr virus capsid antigen complex and their relationship to ZEBRA-associated protein p21 (ZAP21).

The viral capsid antigen complex of Epstein-Barr virus (EBV), an important serodiagnostic marker of infection with the virus, consists of at least four components, with molecular masses of 150, 110, 40, and 21 kDa. Here we show that the 21-kDa component of the viral capsid antigen consists of products of two EBV genes, BFRF3 and BLRF2. Both products were expressed from late transcripts, were recognized by human antisera, and were present in virions. The BFRF3 product, but not that of BLRF2, fulfilled the definition of ZEBRA-associated protein p21 (ZAP21). In cells in which EBV was lytically replicating, BFRF3 protein was coimmunoprecipitated together with ZEBRA by a rabbit antiserum directed against amino acids 197 to 245 of BZLF1. In EBV-negative cells cotransfected with BZLF1 and BFRF3 expression vectors, BFRF3 was also coimmunoprecipitated with this antiserum. Although this antiserum could not detect BFRF3 on an immunoblot, it was able to immunoprecipitate BFRF3 in the absence of ZEBRA expression. The rabbit antiserum to amino acids 197 to 245 of BZLF1 was found to detect the same epitope at the carboxy end of BFRF3 as was recognized by rabbit antiserum to BFRF3 itself. Thus, coimmunoprecipitation of BFRF3 p21 with ZEBRA appeared to be due to cross-reactivity of the immunoprecipitating antiserum rather than to direct association of ZEBRA and BFRF3 p21.

Comparing transcriptional activation and autostimulation by ZEBRA and ZEBRA/c-Fos chimeras.

The lytic cycle of Epstein-Barr virus (EBV) can be activated by transfection of the gene for ZEBRA, a viral basic-zipper (bZip) transcriptional activator. ZEBRA and cellular AP-1 bZip activators, such as c-Fos, have homologous DNA-binding domains, and their DNA-binding specificities overlap. Moreover, EBV latency can also be disrupted by phorbol esters, which act, in part, through AP-1 activators. It is not known whether ZEBRA and AP-1 factors play equivalent roles in the initial stages of reactivation. Here the contribution of ZEBRA's basic DNA recognition domain to disruption of latency was analyzed by comparing ZEBRA with chimeric mutants in which the DNA recognition domain of ZEBRA was replaced with the analogous domain of c-Fos. Chimeric ZEBRA/c-Fos proteins overexpressed in Escherichia coli bound DNA with the specificity of c-Fos; they bound a heptamer AP-1 site and an octamer TPA response element (TRE). ZEBRA bound the AP-1 site and an array of ZEBRA response elements (ZREs). In assays with reporter genes, both ZEBRA and ZEBRA/c-Fos chimeric mutants activated transcription from Zp, a promoter of the ZEBRA gene (BZLF1) that contains the TRE and multiple ZREs. However, despite their capacity to activate reporters bearing Zp, neither ZEBRA nor the c-Fos chimeras activated transcription from Zp in the context of the intact latent viral genome. In contrast, ZEBRA but not ZEBRA/c-Fos chimeras activated Rp, a second viral promoter that controls ZEBRA expression. Hence, transcriptional autostimulation by transfected ZEBRA occurred preferentially at Rp. Both ZEBRA and the ZEBRA/c-Fos chimeras activated transcription from reporters with multimerized AP-1 sites. However, in the context of the virus, only ZEBRA activated the promoters of two early lytic cycle genes, BMRF1 and BMLF1, that contain an AP-1 site. Thus, overexpression of an activator that recognized AP-1 and TRE sites was not sufficient to activate EBV early lytic cycle genes.

Serine-173 of the Epstein-Barr virus ZEBRA protein is required for DNA binding and is a target for casein kinase II phosphorylation.

An Epstein-Barr virus-encoded protein, ZEBRA, mediates the switch from latency to the viral lytic life cycle. ZEBRA's domain structure and DNA binding specificity resemble that of cellular transcriptional activators such as c-Fos/c-Jun. We show that ZEBRA, like c-Jun, is phosphorylated by casein kinase II (CKII). The principal site of phosphorylation is serine-173 (S173), five amino acids upstream of the basic DNA recognition domain. CKII phosphorylation abrogated ZEBRA's capacity to bind its target DNA sequences. S173 is a functional component of ZEBRA's DNA binding domain, since mutation of S173 to alanine (S173A) reduced DNA binding in vitro to 10% of wild-type levels. Transcriptional activation of a native viral promoter in vivo by mutant S173A was also reduced markedly. Reversible phosphorylation of S173 is likely to be an important means of regulating ZEBRA's activity in vivo.