Optimized Cytogenetic Risk-Group Stratification of KMT2A-Rearranged Pediatric Acute Myeloid Leukemia

Comprehensive international consensus on cytogenetic risk-group stratification of KMT2A-rearranged (KMT2A-r) pediatric acute myeloid leukemia (AML) is lacking. This retrospective (2005-2016) International Berlin-Frankfurt-Münster Study Group study on 1,256 children with KMT2A-r AML aimed to validate the prognostic value of established recurring KMT2A fusions and additional cytogenetic aberrations (ACAs), and secondly, to define additional, recurring KMT2A fusions and ACAs, evaluating their prognostic relevance. Compared to our previous study, three additional, recurring KMT2A-r groups were defined: Xq24/KMT2A::SEPT6, 1p32/KMT2A::EPS15, 17q12/t(11;17)(q23;q12). Across 13 KMT2A-r groups, 5-year event-free survival probabilities varied significantly (21.8% to 76.2%; P<0.01). ACAs occurred in 46.8% of 1,200 patients with complete karyotypes, correlating with inferior overall survival (56.8% vs 67.9%; P<0.01). Multivariable analyses confirmed independent associations of 4q21/KMT2A::AFF1, 6q27/KMT2A::AFDN, 10p12/KMT2A::MLLT10, 10p11.2/KMT2A::ABI1, and 19p13.3/KMT2A::MLLT1 with adverse outcomes, but not those of 1q21/KMT2A::MLLT11 and trisomy 19 with favorable and adverse outcomes, respectively. Newly identified ACAs with independent adverse prognoses were monosomy 10, trisomies 1, 6, 16, and X, add(12p), and del(9q). Among patients with 9p22/KMT2A::MLLT3, the independent association of French-American-British-type M5 with favorable outcome was confirmed, and those of trisomy 6 and measurable residual disease at end of induction with adverse outcomes were identified. We provide evidence to incorporate the five adverse-risk KMT2A fusions into the cytogenetic risk-group stratification of KMT2A-r pediatric AML, to revise the favorable-risk classification of 1q21/KMT2A::MLLT11 to intermediate risk, and to refine risk-stratification of 9p22/KMT2A::MLLT3 AML. Future studies should validate the associations between the newly identified ACAs and outcome, and unravel the underlying biological pathogenesis of KMT2A fusions and ACAs.

Measurable Residual Disease and Fusion Partner Independently Predict Survival and Relapse Risk in Childhood KMT2A-Rearranged Acute Myeloid Leukemia: A Study by the International Berlin-Frankfurt-Münster Study Group

PURPOSE

A previous study by the International Berlin-Frankfurt-Münster Study Group (I-BFM-SG) on childhood KMT2A-rearranged (KMT2A-r) AML demonstrated the prognostic value of the fusion partner. This I-BFM-SG study investigated the value of flow cytometry-based measurable residual disease (flow-MRD) and evaluated the benefit of allogeneic stem-cell transplantation (allo-SCT) in first complete remission (CR1) in this disease.

METHODS

A total of 1,130 children with KMT2A-r AML, diagnosed between January 2005 and December 2016, were assigned to high-risk (n = 402; 35.6%) or non-high-risk (n = 728; 64.4%) fusion partner-based groups. Flow-MRD levels at both end of induction 1 (EOI1) and 2 (EOI2) were available for 456 patients and were considered negative (<0.1%) or positive (≥0.1%). End points were 5-year event-free survival (EFS), cumulative incidence of relapse (CIR), and overall survival (OS).

RESULTS

The high-risk group had inferior EFS (30.3% high risk v 54.0% non-high risk; P < .0001), CIR (59.7% v 35.2%; P < .0001), and OS (49.2% v 70.5%; P < .0001). EOI2 MRD negativity was associated with superior EFS (n = 413; 47.6% MRD negativity v n = 43; 16.3% MRD positivity; P < .0001) and OS (n = 413; 66.0% v n = 43; 27.9%; P < .0001), and showed a trend toward lower CIR (n = 392; 46.1% v n = 26; 65.4%; P = .016). Similar results were obtained for patients with EOI2 MRD negativity within both risk groups, except that within the non-high-risk group, CIR was comparable with that of patients with EOI2 MRD positivity. Allo-SCT in CR1 only reduced CIR (hazard ratio, 0.5 [95% CI, 0.4 to 0.8]; P = .00096) within the high-risk group but did not improve OS. In multivariable analyses, EOI2 MRD positivity and high-risk group were independently associated with inferior EFS, CIR, and OS.

CONCLUSION

EOI2 flow-MRD is an independent prognostic factor and should be included as risk stratification factor in childhood KMT2A-r AML. Treatment approaches other than allo-SCT in CR1 are needed to improve prognosis.

Hypodiploidy has unfavorable impact on survival in pediatric acute myeloid leukemia: an I-BFM Study Group collaboration

Hypodiploidy, defined as modal numbers (MNs) 45 or lower, has not been independently investigated in pediatric acute myeloid leukemia (AML) but is a well-described high-risk factor in pediatric acute lymphoblastic leukemia. We aimed to characterize and study the prognostic impact of hypodiploidy in pediatric AML. In this retrospective cohort study, we included children below 18 years of age with de novo AML and a hypodiploid karyotype diagnosed from 2000 to 2015 in 14 childhood AML groups from the International Berlin-Frankfurt-Münster (I-BFM) framework. Exclusion criteria comprised constitutional hypodiploidy, monosomy 7, composite karyotype, and t(8;21) with concurring sex chromosome loss. Hypodiploidy occurred in 81 patients (1.3%) with MNs, 45 (n = 66); 44 (n = 10) and 43 (n = 5). The most frequently lost chromosomes were chromosome 9 and sex chromosomes. Five-year event-free survival (EFS) and overall survival (OS) were 34% and 52%, respectively, for the hypodiploid cohort. Children with MN≤44 (n = 15) had inferior EFS (21%) and OS (33%) compared with children with MN = 45 (n = 66; EFS, 37%; OS, 56%). Adjusted hazard ratios (HRs) were 4.9 (P = .001) and 6.1 (P = .003). Monosomal karyotype or monosomy 9 had particular poor OS (43% and 15%, respectively). Allogeneic stem cell transplantation (SCT) in first complete remission (CR1) (n = 18) did not mitigate the unfavorable outcome of hypodiploidy (adjusted HR for OS was 1.5; P = .42). We identified pediatric hypodiploid AML as a rare subgroup with an inferior prognosis even in the patients treated with SCT in CR1.

Pediatric Cancer Data Commons: Federating and Democratizing Data for Childhood Cancer Research

The international pediatric oncology community has a long history of research collaboration. In the United States, the 2019 launch of the Children's Cancer Data Initiative puts the focus on developing a rich and robust data ecosystem for pediatric oncology. In this spirit, we present here our experience in constructing the Pediatric Cancer Data Commons (PCDC) to highlight the significance of this effort in fighting pediatric cancer and improving outcomes and to provide essential information to those creating resources in other disease areas. The University of Chicago's PCDC team has worked with the international research community since 2015 to build data commons for children's cancers. We identified six critical features of successful data commons design and implementation: (1) establish the need for a data commons, (2) develop and deploy the technical infrastructure, (3) establish and implement governance, (4) make the data commons platform easy and intuitive for researchers, (5) socialize the data commons and create working knowledge and expertise in the research community, and (6) plan for longevity and sustainability. Data commons are critical to conducting research on large patient cohorts that will ultimately lead to improved outcomes for children with cancer. There is value in connecting high-quality clinical and phenotype data to external sources of data such as genomic, proteomics, and imaging data. Next steps for the PCDC include creating an informed and invested data-sharing culture, developing sustainable methods of data collection and sharing, standardizing genetic biomarker reporting, incorporating radiologic and molecular analysis data, and building models for electronic patient consent. The methods and processes described here can be extended to any clinical area and provide a blueprint for others wishing to develop similar resources.

Recommendations for Diagnosis and Treatment of Children with Transient Abnormal Myelopoiesis (TAM) and Myeloid Leukemia in Down Syndrome (ML-DS)

Children with Down syndrome are at a high risk of developing transient abnormal myelopoiesis (TAM; synonym: TMD) or myeloid leukemia (ML-DS). While most patients with TAM are asymptomatic and go into spontaneous remission without a need for therapy, around 20% of patients die within the first six months due to TAM-related complications. Another 20-30% of patients progress from TAM to ML-DS. ML-DS patients are particularly vulnerable to therapy-associated toxicity, but the prognosis of relapsed ML-DS is extremely poor - thus, ML-DS therapy schemata must strive for a balance between appropriate efficacy (to avoid relapses) and treatment-related toxicity. This guideline presents diagnostic and therapeutic strategies for TAM and ML-DS based on the experience and results of previous clinical studies from the BFM working group, which have helped reduce the risk of early death in symptomatic TAM patients using low-dose cytarabine, and which have achieved excellent cure rates for ML-DS using intensity-reduced treatment protocols.

BCR-ABL1 positive AML or CML in blast crisis? A pediatric case report with inv(3) and t(9;22) in the initial clone

The co-occurrence of an inversion inv(3)(q21q26)/GATA2-MECOM and a Philadelphia translocation t(9;22)(q34;q11)/BCR-ABL1 in the context of chronic myeloid leukemia (CML) in blast crisis or acute myeloid leukemia (AML) has only rarely been described. To our knowledge, this co-occurrence has been reported in six pediatric patients with CML but not in pediatric patients with AML. Here, we report on a 7-year-old girl, who, presented with a t(9;22) and inv(3) in 14 of 15 metaphases and an additional monosomy 7 was detected in 5 of these metaphases (ISCN: 46,​XX,​inv(3)(q21q26),​t(9;22)(q34q11)[9]/45,​idem,​-7[5]/46,​XX[1]). The p190 BCR-ABL1 fusion transcript was detected by multiplex PCR and targeted RNA sequencing. Due to these results, a clear distinction between a CML in blast crisis and a BCR-ABL1 positive AML was not possible. The patient was treated according to the treatment recommendations of the AML-BFM study group and additionally received tyrosine kinase inhibitor therapy (Dasatinib). The treatment with Dasatinib was successful in eliminating the inv(3)/t(9;22) clone, but the ancestral inv(3) clone persisted. Based upon these findings we diagnosed an AML with inv(3) and a secondary acquisition of t(9;22). This treatment as well as an allogenic transplantation has led to a complete remission of the disease up to this date (21 months post diagnosis).

Exposure of Patient-Derived Mesenchymal Stromal Cells to TGFB1 Supports Fibrosis Induction in a Pediatric Acute Megakaryoblastic Leukemia Model

Bone marrow fibrosis (BMF) is a rare complication in acute leukemia. In pediatrics, it predominantly occurs in acute megakaryoblastic leukemia (AMKL) and especially in patients with trisomy 21, called myeloid leukemia in Down syndrome (ML-DS). Defects in mesenchymal stromal cells (MSC) and cytokines specifically released by the myeloid blasts are thought to be the main drivers of fibrosis in the bone marrow niche (BMN). To model the BMN of pediatric patients with AMKL in mice, we first established MSCs from pediatric patients with AMKL (n = 5) and ML-DS (n = 9). Healthy donor control MSCs (n = 6) were generated from unaffected children and adolescents ≤18 years of age. Steady-state analyses of the MSCs revealed that patient-derived MSCs exhibited decreased adipogenic differentiation potential and enrichment of proliferation-associated genes. Importantly, TGFB1 exposure in vitro promoted early profibrotic changes in all three MSC entities. To study BMF induction for longer periods of time, we created an in vivo humanized artificial BMN subcutaneously in immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice, using a mixture of MSCs, human umbilical vein endothelial cell, and Matrigel. Injection of AMKL blasts as producers of TGFB1 into this BMN after 8 weeks induced fibrosis grade I/II in a dose-dependent fashion over a time period of 4 weeks. Thus, our study developed a humanized mouse model that will be instrumental to specifically examine leukemogenesis and therapeutic targets for AMKL blasts in future. IMPLICATIONS: TGFB1 supports fibrosis induction in a pediatric AMKL model generated with patient-derived MSCs. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/18/10/1603/F1.large.jpg.

Akute Promyelozyten-Leukämie: Neue Behandlungsstrategien mit ATRA und ATO – AML-BFM-Empfehlungen

Die Behandlung der Akuten Promyelozyten-Leukämie (APL) hat sich in den letzten Jahren deutlich geändert. Heute können APL Patienten mit Standardrisiko – (auch als Niedrigrisiko bezeichnet) ohne Chemotherapie nur mit all-trans-Retinsäure (ATRA) und Arsentrioxid (ATO) behandelt werden. Bei Hochrisikopatienten sollte eine Induktions-Chemotherapie hinzugefügt werden. Die kurativen Ergebnisse sind gut und vergleichbar mit jenen, die in der Vergangenheit mit Chemotherapie plus ATRA erzielt wurden. Toxizitäten, insbesondere infektiöse Komplikationen sind jedoch deutlich seltener. Das Hauptrisiko bleiben frühe letale Blutungen. Durch rechtzeitige Diagnose und frühe ATRA-Behandlung kann dieses Risiko reduziert werden. In der vorliegenden Übersicht werden die aktuellen Behandlungsstrategien und Empfehlungen für APL bei Kindern dargestellt und diskutiert.

Gemtuzumab ozogamicin in children with relapsed or refractory acute myeloid leukemia: a report by Berlin-Frankfurt-Münster study group

Despite intensified salvage treatments, children with relapsed/refractory acute myeloid leukemia (AML) have poor survival. We evaluated gemtuzumab ozogamicin (CD33-targeted drug) used on a compassionate basis in patients diagnosed from 1995 until 2014 within Acute Myeloid Leukemia Berlin-Frankfurt-Münster studies, and identified 76 patients (<18 years) with highly-advanced and pre-treated AML [refractory de novo acute myeloid leukemia (n=10), de novo AML refractory to relapse (1^st early: n=41; 1^st late: n=10; 2^nd or more: n=10), and secondary AML (n=5)]. At doses of 2.5–10 mg/m², gemtuzumab ozogamicin was administered in 1-4 cycles as single agent (47%), combined with cytarabine (47%), or others (6%). Most common grade 3/4 adverse events were infections or febrile neutropenia (78% of severe adverse events), infusion-related immunological reactions (6%), and gastrointestinal symptoms (5%). Three patients experienced veno-occlusive disease (one fatal due to exacerbation of a pre-existing cardiomyopathy). Sixty-four percent received subsequent hematopoietic stem cell transplantation. Probability of 4-year overall survival was 18±5% in all, 27±7% in patients with and 0% in patients without hematopoietic stem cell transplantation (P<0.0001). Administration of gemtuzumab ozogamicin on a patient-specific, compassionate use basis was frequently considered in our study group and proved to be effective for bridging children with very advanced AML to hematopoietic stem cell transplantation. Uniform prospective studies for these patients are urgently needed.

Clofarabine, high-dose cytarabine and liposomal daunorubicin in pediatric relapsed/refractory acute myeloid leukemia: a phase IB study

Survival in children with relapsed/refractory acute myeloid leukemia is unsatisfactory. Treatment consists of one course of fludarabine, cytarabine and liposomal daunorubicin, followed by fludarabine and cytarabine and stem-cell transplantation. Study ITCC 020/I-BFM 2009-02 aimed to identify the recommended phase II dose of clofarabine replacing fludarabine in the abovementioned combination regimen (3+3 design). Escalating dose levels of clofarabine (20-40 mg/m²/day × 5 days) and liposomal daunorubicin (40-80 mg/m²/day) were administered with cytarabine (2 g/m²/day × 5 days). Liposomal DNR was given on day 1, 3 and 5 only. The cohort at the recommended phase II dose was expanded to make a preliminary assessment of anti-leukemic activity. Thirty-four children were enrolled: refractory 1^st (n=11), early 1st (n=15), ≥2^nd relapse (n=8). Dose level 3 (30 mg/m²clofarabine; 60 mg/m²liposomal daunorubicin) appeared to be safe only in patients without subclinical fungal infections. Infectious complications were dose-limiting. The recommended phase II dose was 40 mg/m² clofarabine with 60 mg/m² liposomal daunorubicin. Side-effects mainly consisted of infections. The overall response rate was 68% in 31 response evaluable patients, and 80% at the recommended phase II dose (n=10); 22 patients proceeded to stem cell transplantation. The 2-year probability of event-free survival (pEFS) was 26.5±7.6 and probability of survival (pOS) 32.4±8.0%. In the 21 responding patients, the 2-year pEFS was 42.9±10.8 and pOS 47.6±10.9%. Clofarabine exposure in plasma was not significantly different from that in single-agent studies. In conclusion, clofarabine was well tolerated and showed high response rates in relapsed/refractory pediatric acute myeloid leukemia. Patients with (sub) clinical fungal infections should be treated with caution. Clofarabine has been taken forward in the Berlin-Frankfurt-Münster study for newly diagnosed acute myeloid leukemia. The Study ITCC-020 was registered as EUDRA-CT 2009-009457-13; Dutch Trial Registry number 1880.

Childhood cancer predisposition syndromes-A concise review and recommendations by the Cancer Predisposition Working Group of the Society for Pediatric Oncology and Hematology

Heritable predisposition is an important cause of cancer in children and adolescents. Although a large number of cancer predisposition genes and their associated syndromes and malignancies have already been described, it appears likely that there are more pediatric cancer patients in whom heritable cancer predisposition syndromes have yet to be recognized. In a consensus meeting in the beginning of 2016, we convened experts in Human Genetics and Pediatric Hematology/Oncology to review the available data, to categorize the large amount of information, and to develop recommendations regarding when a cancer predisposition syndrome should be suspected in a young oncology patient. This review summarizes the current knowledge of cancer predisposition syndromes in pediatric oncology and provides essential information on clinical situations in which a childhood cancer predisposition syndrome should be suspected.

Improved outcome of pediatric patients with acute megakaryoblastic leukemia in the AML-BFM 04 trial

Despite recent advances in the treatment of children with acute megakaryoblastic leukemia (AMKL) using intensified treatment protocols, clear prognostic indicators, and treatment recommendations for this acute myeloid leukemia (AML) subgroup are yet to be defined. Here, we report the outcome of 97 pediatric patients with de novo AMKL (excluding Down syndrome [DS]) enrolled in the prospective multicenter studies AML-BFM 98 and AML-BFM 04 (1998-2014). AMKL occurred in 7.4 % of pediatric AML cases, at younger age (median 1.44 years) and with lower white blood cell count (mean 16.5 × 10⁹/L) as compared to other AML subgroups. With 60 ± 5 %, children with AMKL had a lower 5-year overall survival (5-year OS; vs. 68 ± 1 %, P_{log rank} = 0.038). Yet, we achieved an improved 5-year OS in AML-BFM 04 compared to AML-BFM 98 (70 ± 6 % vs. 45 ± 8 %, P_{log rank} = 0.041). Allogeneic hematopoietic stem cell transplantation in first remission did not provide a significant survival benefit (5-year OS 70 ± 11 % vs. 63 ± 6 %; P_Mantel-Byar = 0.85). Cytogenetic data were available for n = 78 patients. AMKL patients with gain of chromosome 21 had a superior 5-year OS (80 ± 9 %, P_{log rank} = 0.034), whereas translocation t(1;22)(p13;q13) was associated with an inferior 5-year event-free survival (38 ± 17 %, P_{log rank} = 0.04). However, multivariate analysis showed that treatment response (bone marrow morphology on day 15 and 28) was the only independent prognostic marker (RR = 4.39; 95 % CI, 1.97–9.78). Interestingly, GATA1-mutations were detected in six patients (11 %) without previously known trisomy 21. Thus, AMKL (excluding DS) remains an AML subgroup with inferior outcome. Nevertheless, with intensive therapy regimens, a steep increase in the survival rates was achieved.

miR-99a/100~125b tricistrons regulate hematopoietic stem and progenitor cell homeostasis by shifting the balance between TGFβ and Wnt signaling

miR-99a/100, let-7, and miR-125b paralogs are encoded in two tricistrons and are highly expressed in hematopoietic stem cells (HSCs). Emmrich et al. demonstrate that miR-99a/100∼125b tricistrons are transcribed as a polycistronic message and functionally converge at the combinatorial block of the TGFβ pathway. Down-regulating tumor suppressor genes APC/APC2 stabilized active β-catenin and enhanced Wnt signaling. These tricistronic miRNAs promoted sustained expansion of murine and human HSCs by switching the balance between Wnt and TGFβ signaling.

Although regulation of stem cell homeostasis by microRNAs (miRNAs) is well studied, it is unclear how individual miRNAs genomically encoded within an organized polycistron can interact to induce an integrated phenotype. miR-99a/100, let-7, and miR-125b paralogs are encoded in two tricistrons on human chromosomes 11 and 21. They are highly expressed in hematopoietic stem cells (HSCs) and acute megakaryoblastic leukemia (AMKL), an aggressive form of leukemia with poor prognosis. Here, we show that miR-99a/100∼125b tricistrons are transcribed as a polycistronic message transactivated by the homeobox transcription factor HOXA10. Integrative analysis of global gene expression profiling, miRNA target prediction, and pathway architecture revealed that miR-99a/100, let-7, and miR-125b functionally converge at the combinatorial block of the transforming growth factor β (TGFβ) pathway by targeting four receptor subunits and two SMAD signaling transducers. In addition, down-regulation of tumor suppressor genes adenomatous polyposis coli (APC)/APC2 stabilizes active β-catenin and enhances Wnt signaling. By switching the balance between Wnt and TGFβ signaling, the concerted action of these tricistronic miRNAs promoted sustained expansion of murine and human HSCs in vitro or in vivo while favoring megakaryocytic differentiation. Hence, our study explains the high phylogenetic conservation of the miR-99a/100∼125b tricistrons controlling stem cell homeostasis, the deregulation of which contributes to the development of AMKL.

Improved generation of patient-specific induced pluripotent stem cells using a chemically-defined and matrigel-based approach

Reprogramming of somatic cells into patient-specific pluripotent analogues of human embryonic stem cells (ESCs) emerges as a prospective therapeutic angle in molecular medicine and a tool for basic stem cell biology. However, the combination of relative inefficiency and high variability of non-defined culture conditions precluded the use of this technique in a clinical setting and impeded comparability between laboratories. To overcome these obstacles, we sequentially devised a reprogramming protocol using one lentiviral-based polycistronic reprogramming construct, optimized for high co-expression of OCT4, SOX2, KLF4 and MYC in conjunction with small molecule inhibitors of non-permissive signaling cascades, such as transforming growth factor β (SB431542), MEK/ERK (PD0325901) and Rho-kinase signaling (Thiazovivin), in a defined extracellular environment. Based on human fetal liver fibroblasts we could efficiently derive induced pluripotent stem cells (iPSCs) within 14 days. We attained efficiencies of up to 10.97±1.71% resulting in 79.5- fold increase compared to non-defined reprogramming using four singular vectors. We show that the overall increase of efficiency and temporal kinetics is a combinatorial effect of improved lentiviral vector design, signaling inhibition and definition of extracellular matrix (Matrigel®) and culture medium (mTESR®1). Using this protocol, we could derive iPSCs from patient fibroblasts, which were impermissive to classical reprogramming efforts, and from a patient suffering from familial platelet disorder. Thus, our defined protocol for highly efficient reprogramming to generate patient-specific iPSCs, reflects a big step towards therapeutic and broad scientific application of iPSCs, even in previously unfeasible settings.

Characterization of the metal centers of the Ni/Fe-S component of the carbon-monoxide dehydrogenase enzyme complex from Methanosarcina thermophila

Methanosarcina thermophila contains a multienzyme complex called the carbon-monoxide dehydrogenase complex, which has been resolved into a nickel/iron-sulfur and a corrinoid/iron-sulfur component. This complex plays a central role in acetoclastic methanogenesis. The Ni/Fe-S component catalyzes CO oxidation and has been proposed to be involved in cleavage of acetyl-CoA into its methyl, carbonyl, and CoA moieties. In the work reported here, three metal centers in the Ni/Fe-S component were characterized by electron paramagnetic resonance (EPR) spectroscopy and spectroelectrochemistry and pre-steady state kinetics. Center A contains nickel and iron and forms an EPR active adduct with CO, which is called the NiFeC species. The EPR spectrum of the NiFeC species has g values of 2.059, 2.051, and 2.029 and is observable at temperatures as high as 150 K. This signal had previously been observed only in the carbon-monoxide dehydrogenase complex of M. thermophila and the acetyl-CoA synthase from acetate-producing bacteria. Incubation of the CO-reduced Ni/Fe-S component with acetyl-CoA resulted in an increase in intensity of the NiFeC signal, which supports a role for the component in the cleavage of acetyl-CoA. Generation of the NiFeC EPR signal occurs with a rate constant of 0.4 s-1, a result that demonstrates the kinetic competence of this species in the acetyl-CoA cleavage reaction but rules it out as the site of oxidation of CO to CO2. Center B is likely to be a [4Fe-4S]2+/1+ center with g values of 2.04, 1.93, and 1.89 (gav = 1.95) and a standard reduction potential (E'0) of -444 mV. At potentials less than -500 mV, another EPR signal develops that appears to originate from another state of Center B. Center C is a fast relaxing center with g values of 2.02, 1.88, and 1.71 (gav = 1.87) and an E'0 of -154 mV.

[Resorption of prostaglandin E2 following various methods of local administration for ripening of the cervix and end the induction of labor]

PGEM concentration was determined radioimmunologically in a non-pregnant woman in whom PGE2 was infused intravenously at increasing dosage and in women in whom labour was induced by various methods for local application of PGE2. There was excellent correlation between the amount of PGE2 infused intravenously and the levels of PGEM determined in the peripheral plasma. The following methods of local application of PGE2 were included in the study: 0.4 mg PGE2 gel placed retroamnially by means of a balloon catheter; 0.4 and 0.5 mg PGE2 gel applied endocervically; 1.5 mg PGE2 given pericervically through a portio adapter and 3 mg PGE2 placed intravaginally in form of a single vaginal tablet; also included was a control group where only vaginal examination was performed. Blood was withdrawn before, and then 30 minutes, 1, 2 and 3 hours after PGE2 administration. Mean levels of PGEM in the maternal peripheral plasma showed no change within or between the various groups, with the exception of one patient in the portio adapter group where hyperstimulation occurred. After removal of the adapter PGEM levels dropped to baseline values. It is concluded from the present study that local application of doses currently used to soften the cervix and/or induce labour at term does not give rise to PGEM concentrations in the maternal blood of the same magnitude as achieved by intravenous PGE2 administration.

[Premature membrane rupture: effect of intracervical PGE2 gel administration on plasma oxytocin, PGFM and PGEM levels in mother and child]

Premature rupture (= PR) of the amnion is a serious complication even for the mature child if it occurs earlier than 24 hours before birth. To keep the interval as short as possible, the authors induce labour from week 35/0 in case of PR, provided the Bishop score is greater than 7. If the bishop score is lower, they conduct intracervical priming of the cervix with 0.4 mg PGE2 gel before induction of labour. This has proved clinically superior to intravenous procedures. In the study presented here, the authors attempted to find out whether intracervical administration of PGE2 gel would result in changes in the maternal and foetal plasma concentrations of oxytocin, PGFM, or PGEM when comparing conditions in case of ruptured amnion with those if the amnion remained intact. If the amnion is intact and the cervix immature (less than 2 cm), intracervical administration of 0.4 mg PGE2 gel produces a significant OT increase within 30 minutes. From a cervical width of 2 cm onwards, the OT levels are already primarily enhanced and will hardly change even after PGE2 gel administration. Similar conditions obtain in PR. PGFM plasma levels will rise only slightly within an hour after intracervical PGE2 gel administration, independent of whether there has been a rupture or not, or whether the cervix is dilated less than 2 cm or 2 cm and more.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma concentration of 13,14-dihydro-15-keto-PGE2 (PGEM) after various ways of cervix ripening with PGE2

PGEM concentration was determined radioimmunologically in a non-pregnant woman, in whom PGE2 was infused intravenously at increasing rates and in women, in whom labor was induced by various methods for local application of PGE2. There was excellent correlation between the amount of PGE2 infused intravenously and the levels of PGEM determined in the peripheral plasma. The following methods of local application of PGE2 were included in the study: 0.4 mg PGE2 gel placed retroamnially by means of a balloon catheter, 0.4 and 0.5 mg PGE2 applied endocervically and 3 mg PGE2 placed intravaginally in form of a single vaginal tablet; also included was a control-group, where only vaginal examination was performed. Bloods were drawn before, 30 minutes, 1, 2 and 3 hours after PGE2 administration. Mean levels of PGEM in the maternal peripheral plasma did not change neither within nor between the various groups. It is concluded from the present study, that local application of doses currently used to soften the cervix and/or induce labor at term do not lead to the same PGEM-concentration in the maternal blood as after intravenous infusion of PGE2 in doses normally used to induce labor.