Mirjam Kunze

Enterococcal colonization of infants in a neonatal intensive care unit: associated predictors, risk factors and seasonal patterns

BackgroundDuring and shortly after birth, newborn infants are colonized with enterococci. This study analyzes predictors for early enterococcal colonization of infants in a neonatal intensive care unit and describes risk factors associated with multidrugresistant enterococci colonization and its seasonal patterns.MethodsOver a 12-month period, we performed a prospective epidemiological study in 274 infants admitted to a neonatal intensive care unit. On the first day of life, we compared infants with enterococcal isolates detected in meconium or body cultures to those without. We then tested the association of enterococcal colonization with peripartal predictors/risk factors by using bivariate and multivariate statistical methods.ResultsTwenty-three percent of the infants were colonized with enterococci. The three most common enterococcal species were E. faecium (48% of isolates), E. casseliflavus (25%) and E. faecalis (13%). Fifty-seven percent of the enterococci found were resistant to three of five antibiotic classes, but no vancomycin-resistant isolates were observed. During winter/spring months, the number of enterococci and multidrug-resistant enterococci were higher than in summer/fall months (p = 0.002 and p < 0.0001, respectively). With respect to enterococcal colonization on the first day of life, predictors were prematurity (p = 0.043) and low birth weight (p = 0.011). With respect to colonization with multidrug-resistant enterococci, risk factors were prematurity (p = 0.0006), low birth weight (p < 0.0001) and prepartal antibiotic treatment (p = 0.019). Using logistic regression, we determined that gestational age was the only parameter significantly correlated with multidrug-resistant enterococci colonization. No infection with enterococci or multidrugresistant enterococci in the infants was detected. The outcome of infants with and without enterococcal colonization was the same with respect to death, necrotizing enterocolitis, intracerebral hemorrhage and bronchopulmonary dysplasia.ConclusionIn neonatal intensive care units, an infants susceptibility to early colonization with enterococci in general, and his or her risk for colonization with multidrug-resistant enterococci in particular, is increased in preterm newborns, especially during the winter/spring months. The prepartal use of antibiotics with no known activity against enterococci appears to increase the risk for colonization with multidrug-resistant enterococci.

Haematopoietic stem cell survival and transplantation efficacy is limited by the BH3‐only proteins Bim and Bmf

Anti‐apoptotic Bcl‐2 family members are critical for the regulation of haematopoietic stem and progenitor cell (HSPC) survival. Little is known about the role of their pro‐apoptotic antagonists, i.e. ‘BH3‐only’ proteins, in this cell compartment. Based on the analysis of cytokine deprivation‐induced changes in mRNA expression levels of Bcl‐2 family proteins, we determined the consequences of BH3‐only protein depletion on HSPC survival in culture and, for selected candidates, on engraftment in vivo. Thereby, we revealed a critical role for Bim and Bmf as regulators of HSPC dynamics both during early engraftment and long‐term reconstitution. HSPCs derived from wild‐type donors were readily displaced by Bim‐ or Bmf‐deficient or Bcl‐2‐overexpressing HSPCs as early as 10 days after engraftment. Moreover, in the absence of Bim, significantly lower numbers of transplanted HSPCs were able to fully engraft radio‐depleted recipients. Finally, we provide proof of principle that RNAi‐based reduction of BIM or BMF, or overexpression of BCL‐2 in human CD34+ cord blood cells may be an attractive therapeutic option to increase stem cell survival and transplantation efficacy.

A Feeder-Free Differentiation System Identifies Autonomously Proliferating B Cell Precursors in Human Bone Marrow

The peripheral B cell compartment is maintained by homeostatic proliferation and through replenishment by bone marrow precursors. Because hematopoietic stem cells cycle at a slow rate, replenishment must involve replication of precursor B cells. To study proliferation of early human B cell progenitors, we established a feeder cell–free in vitro system allowing the development of B cells from CD34+ hematopoietic stem cells up to the stage of immature IgM+ B cells. We found that pro-B and pre-B cells generated in vitro can proliferate autonomously and persist up to 7 wk in culture in the absence of signals induced by exogenously added cytokines. Nevertheless, addition of IL-7 enhanced pre-B cell expansion and inhibited maturation into IgM+ B cells. The B cell precursor subsets replicating in vitro were highly similar to the bone marrow B cell precursors cycling in vivo. The autonomous proliferation of B cell precursor subsets in vitro and their long-term persistence implies that proliferation during pro-B and pre-B cell stages plays an important role in the homeostasis of the peripheral B cell compartment. Our in vitro culture can be used to study defects in B cell development or in reconstitution of the B cell pool after depletion and chemotherapy.

Fulminant neonatal sepsis due to Streptococcus alactolyticus -A case report and review

Group D streptococci have rarely been associated with neonatal infections. We report a case of fulminant respiratory distress syndrome (RDS) caused by Streptococcus alactolyticus in a term neonate. Gram staining revealed gram‐positive cocci and culture grew group D streptococci in samples taken from trachea, ear, and nasopharynx. Streptococcus alactolyticus was identified using automated microbial identification system (Vitek 2). Histopathology showed massive pulmonary inflammation with intra‐alveolar granulocytosis and secondary pulmonary bleeding as etiology of fatal outcome. To our knowledge, this is first case presenting neonatal infection caused by Streptococcus alactolyticus.

Overexpression of hypoxia-inducible factor-1 alpha improves vasculogenesis-related functions of endothelial progenitor cells

Postnatal vasculogenesis is mediated by mobilization of endothelial progenitor cells (EPCs) from bone marrow and homing to ischemic tissues. This feature emphasizes this cell type for cell-based therapies aiming at the improvement of neovascularization in tissue engineering applications and regenerative medicine. In animal models, it was demonstrated that implantation of EPCs from cord blood (cbEPCs) led to the formation of a complex functional neovasculature, whereas EPCs isolated from adult peripheral blood (pbEPCs) showed a limited vasculogenic potential, which may be attributed to age-related dysfunction. Recently, it was demonstrated that activation of hypoxia-inducible factor-1α (Hif-1α) improves cell functions of progenitor cells of mesenchymal and endothelial origin. Thus, we hypothesized that overexpression of Hif-1α may improve the vasculogenesis-related phenotype of pbEPCs. In the present study, we overexpressed Hif-1α in pbEPCs and cbEPCs by using recombinant adenoviruses and investigated effects on stem cell- and vasculogenesis-related cell parameters. Overexpression of Hif-1α enhanced proliferation, invasion, cell survival and in vitro capillary sprout formation of both EPC populations. Migration was increased in cbEPCs upon Hif-1α overexpression, but not in pbEPCs. Cellular senescence was decreased in pbEPCs, while remained in cbEPCs, which showed, as expected, intrinsically a dramatically lower senescent phenotype in relation to pbEPCs. Similarly, the colony-formation capacity was much higher in cbEPCs in comparison to pbEPCs and was further increased by Hif-1α overexpression, whereas Hif-1α transduction exerted no significant influence on colony formation of pbEPCs. In summary, our experiments illustrated multifarious effects of Hif-1α overexpression on stem cell and vasculogenic parameters. Therefore, Hif-1α overexpression may represent a therapeutic option to improve cellular functions of adult as well as postnatal EPCs.

[Psychological consequences of perinatal loss in subsequent pregnancies--a comparative study].

PURPOSE Pregnancies after perinatal loss occur often. However, little is known about the need of secondary psychological prevention in these instances. Therefore we investigated psychological disorder and distress during the subsequent pregnancy after perinatal loss. METHODS We compared psychological symptoms in pregnant women with and without previous perinatal loss. RESULTS Pregnant women in the PL-group did not suffer more from depression, anxiety and other psychological distress than women without perinatal loss. Nearly a third of the women in the PL-group were classified as unresolved with regard to their mental representation of attachment indicating that their mourning process was still not completed. CONCLUSION Women who have suffered from perinatal loss do not score higher on depression, anxiety or general psychopathology during subsequent pregnancies than women without loss experience. Only a minority of women, who have suffered from loss show ongoing signs of unresolved mourning. However, in order to detect criteria for the identification of those who might be at risk during subsequent pregnancies studies with larger samples size are necessary.

Long-term serial xenotransplantation of juvenile myelomonocytic leukemia recapitulates human disease in Rag2-/-γc-/- mice.

Juvenile myelomonocytic leukemia is a clonal malignant disease affecting young children. Current cure rates, even with allogeneic hematopoietic stem cell transplantation, are no better than 50%–60%. Pre-clinical research on juvenile myelomonocytic leukemia is urgently needed for the identification of novel therapies but is hampered by the unavailability of culture systems. Here we report a xenotransplantation model that allows long-term in vivo propagation of primary juvenile myelomonocytic leukemia cells. Persistent engraftment of leukemic cells was achieved by intrahepatic injection of 1×106 cells into newborn Rag2−/−γc−/− mice or intravenous injection of 5×106 cells into 5-week old mice. Key characteristics of juvenile myelomonocytic leukemia were reproduced, including cachexia and clonal expansion of myelomonocytic progenitor cells that infiltrated bone marrow, spleen, liver and, notably, lung. Xenografted leukemia cells led to reduced survival of recipient mice. The stem cell character of juvenile myelomonocytic leukemia was confirmed by successful serial transplantation that resulted in leukemia cell propagation for more than one year. Independence of exogenous cytokines, low donor cell number and slowly progressing leukemia are advantages of the model, which will serve as an important tool to research the pathophysiology of juvenile myelomonocytic leukemia and test novel pharmaceutical strategies such as DNA methyltransferase inhibition.

Transient apoptosis inhibition in donor stem cells improves hematopoietic stem cell transplantation

During hematopoietic stem cell transplantation, a substantial number of donor cells are lost because of apoptotic cell death. Transplantation-associated apoptosis is mediated mainly by the proapoptotic BCL-2 family proteins BIM and BMF, and their proapoptotic function is conserved between mouse and human stem and progenitor cells. Permanent inhibition of apoptosis in donor cells caused by the loss of these BH3-only proteins improves transplantation outcome, but recipients might be exposed to increased risk of lymphomagenesis or autoimmunity. Here, we address whether transient inhibition of apoptosis can serve as a safe but efficient alternative to improve the outcome of stem cell transplantation. We show that transient apoptosis inhibition by short-term overexpression of prosurvival BCL-XL, known to block BIM and BMF, is not only sufficient to increase the viability of hematopoietic stem and progenitor cells during engraftment but also improves transplantation outcome without signs of adverse pathologies. Hence, this strategy represents a promising and novel therapeutic approach, particularly under conditions of limited donor stem cell availability.

Clinical risk factors for complete and partial placental retention - a case-control study.

Abstract Objective: We sought to investigate the incidence, maternal risk factors, and perinatal outcomes of women with complete and partial placental retention in a tertiary care teaching hospital in Southwestern Germany. Study design: We performed an unmatched case-control study with cases occurring between July 2000 and June 2007. Women were included into the study if they completed at least the 24th week of gestation and were diagnosed with placental retention requiring surgical intervention. We selected two controls per case and performed univariate and multivariate logistic regression analyses to identify risk factors for complete and partial placental retention. Results: A total of 161 cases (2.02%) were identified out of 7978 deliveries. The 1-year prevalence of all types of placental retention continuously increased during the 6-year study period from 0.93% to 3.26%. A significant independent risk factor for all types of placental retention in the multivariate logistic regression model was a previous retention of the placenta [odds ratio (OR)=21.723, 95% confidence interval (CI) 6.07–77.7]. Independent protective factors against all types of placental retention were a non-anterior and non-posterior placenta location (OR=0.561, 95% CI 0.35–0.91), and a cesarean delivery with (OR=0.193, 95% CI 0.09–0.40) and without labor (OR=0.482, 95% CI 0.27–0.86). Women without partial placental retention delivered neonates with better 5-min APGAR scores (OR=0.78, 95% CI 0.65–0.95). Conclusion: A thorough medical history and a vigilant prepartum ultrasound help in identifying women at risk for placental retention.

Treatment of very preterm preeclampsia via heparin-mediated extracorporeal LDL-precipitation (H.E.L.P.) apheresis: The Freiburg preeclampsia H.E.L.P.-Apheresis study

OBJECTIVE Soluble Fms-like tyrosine kinase-1 (sFlt-1) is thought to be causative in the pathogenesis of preeclampsia (PE) and specific removal of sFlt-1 via dextran sulfate cellulose (DSC)-apheresis was suggested as cure to allow prolongation of pregnancy in preterm PE. However, in addition a deranged lipoprotein metabolism may impact endothelial and placental function in PE. Lipoprotein-apheresis by heparin-mediated extracorporeal LDL-precipitation (H.E.L.P.) was previously applied and has been shown to alleviate symptoms in PE. This clinical trial reevaluates the clinical efficacy of H.E.L.P.-apheresis in PE considering sFlt-1. STUDY DESIGN Open pilot study assessing the prolongation by H.E.L.P.-apheresis in 6 women (30-41 years) with very preterm PE (24+4 to 27+0 gestational weeks (GW)) (NCT01967355) compared to a historic control-group matched for GW at admission (<28 GW; n = 6). Clinical outcome of mothers and babies, and pre- and post H.E.L.P.-apheresis levels of sFlt-1 and PlGF were monitored. MAIN OUTCOME MEASURES In apheresis patients (2-6 treatments), average time from admission to birth was 15.0 days (6.3 days in controls; p = 0.027). Lung maturation was induced in all treated cases, and all children were released in healthy condition. Apheresis reduced triglycerides and LDL-cholesterol by more than 40%. Although H.E.L.P.-apheresis induced a transient peak baseline levels did not change and rather stabilized sFlt-1 levels at pre-apheresis levels throughout treatments, with sFlt-1/PLGF ratio remaining unaffected. CONCLUSIONS H.E.L.P.-apheresis proved again to be safe and prolongs pregnancies in PE. However, without changing sFlt-1 levels below baseline lowering lipids or other yet undefined factors appear to be of more relevance than reducing sFlt-1.