Peritonitis in children on peritoneal dialysis in Cape Town, South Africa: epidemiology and risks

Peritonitis is a frequent complication of peritoneal dialysis (PD) in children as well in adults. Data on PD and peritonitis in pediatric patients are very scarce in developing countries. A retrospective cohort study was performed between 2000 and 2008 with the aim to evaluate PD treatment and peritonitis epidemiology in pediatric patients in South Africa and identify risk factors for peritonitis. Baseline characteristics and potential risk factors of peritonitis were recorded, including housing, socio-economic circumstances, distance to PD center, type of PD, mode of catheter placement, race, presence of gastrostomy tube, weight, and height. Outcome indices for peritonitis were peritonitis rate, time to first peritonitis, and number of peritonitis-free patients. The patient cohort comprised 67 patients who were on PD for a total of 544 months. The total number of peritonitis episodes was 129. Median peritonitis rate was one episode every 4.3 patient months (2.8 episodes/patient-year, range 0–21.2). Median time to first infection was 2.03 months (range 0.1–21.5 months), and 28.4% of patients remained free from peritonitis. Patients with good housing and good socio-economic circumstances had a significantly lower peritonitis rate and a longer time to first peritonitis episode. Peritonitis rate was high in this cohort, compared to numbers reported for the developed world; the characteristics of causative organisms are comparable. The most important risk factors for the development of peritonitis were poor housing and poor socio-economic circumstances. More intensive counseling may be beneficial, but improvement of general socio-economic circumstances will have the greatest influence on PD success

A Matched Case Control Study of Surgically and Non-surgically Treated Patent Ductus Arteriosus in Extremely Pre-term Infants

Introduction: There are still uncertainties about the timing and indication for surgical ligation of patent ductus arteriosus (PDA) in pre-term infants, where lower gestational age (GA) usually is predictive for surgical treatment. Objective: Our aim was to assess differences in clinical characteristics and outcomes between surgically treated and matched non-surgically treated PDA in extremely pre-term infants. Methods: All extremely pre-term infants born 2010-2016 with surgically treated PDA (Ligated group; n = 44) were compared to non-surgically treated infants (Control group; n = 44) matched for gestational age (+/-1 week) and time of birth (+/-1 month). Perinatal parameters, echocardiographic variables, details of pharmacological PDA treatment, morbidity, and mortality were assessed. Result: Mean GA and birthweight were similar between the Ligated group (24(+5) +/- 1(+3) weeks and 668 +/- 170 g) and the Control group (24(+5) +/- 1(+3) weeks and 704 +/- 166 g; p = 1.000 and p = 0.319, respectively). Infants in the Ligated group had larger ductal diameters prior to pharmacological treatment, and lack of diameter decrease and PDA closure after treatment (p = 0.022, p = 0.043 and 0.006, respectively). Transfusions, post-natal steroids and invasive respiratory support were more common in the Ligated group. Except for a higher incidence of severe bronchopulmonary dysplasia (BPD) in the Ligated group there were no other differences in outcomes or mortality between the groups. Conclusion: Early large ductal diameter and reduced responsiveness to pharmacological treatment predicted the need for future surgical ligation in this matched cohort study of extremely pre-term infants where the effect of GA and differences in treatment strategies were excluded. Besides an increased incidence of severe BPD in the Ligated group, no other differences in morbidity or mortality were detected

Active versus restrictive ligation strategy for patent ductus arteriosus : A retrospective two-center study of extremely preterm infants born between 22 + 0 and 25 + 6 weeks of gestational age

Background Patent ductus arteriosus (PDA) in premature infants is associated with adverse clinical outcomes. Mode and timing of treatment are still controversial. Data are limited in the most extremely premature infants <26 weeks of gestational age (GA), where clinical problems are most significant and patients are most vulnerable. Aims To investigate whether different approaches to surgical closure of PDA in two large Swedish centers has an impact on clinical outcomes including mortality in extremely preterm infants born <26 weeks GA. Study design Retrospective, two-center, cohort study. Subjects Infants born at 22+0–25+6 weeks GA between 2010 and 2016 at Uppsala University Children's Hospital (UUCH; n = 228) and Queen Silvia Children's Hospital Gothenburg (QSCHG; n = 220). Main outcome measures Survival, bronchopulmonary dysplasia (BPD), and retinopathy of prematurity (ROP). Results Surgical closure of PDA was more common and performed earlier at QSCHG (50 % vs 16 %; median age 11 vs 44 days; p < 0.01). Survival was similar in both centres. There was a higher incidence of severe BPD and longer duration of mechanical ventilation at UUCH (p < 0.01). There was a higher incidence of ROP, IVH and sepsis at QSCH (p < 0.05, p < 0.01 and p < 0.01). A sub-group analysis matching all surgically treated infants at QSCHG with infants at UUCH with the same GA showed similar results as the total cohort. Conclusion Earlier and higher rate of surgical PDA closure in this cohort of extremely preterms born <26 weeks GA did not impact mortality but was associated with lower rates of severe BPD and higher rates of severe ROP

Monitoring light/dark association dynamics of multi-protein complexes in cyanobacteria using size exclusion chromatography-based proteomics

Diurnal rhythms are recurring 24h patterns such as light/dark cycles that affect many natural environmental and biological processes. The cyanobacterium Synechococcus elongatus PCC 7942 (S. elongatus) produces its energy through photosynthesis and therefore its internal molecular machinery is strongly influenced by these diurnal rhythms. Moreover, it has one of the simplest, self-sustained, circadian rhythms, extensively studied functionally and structurally. These characteristics together with the relatively small genome of S. elongatus, make it an ideal model system for the study of diurnal and circadian rhythms. Although expression of many gene transcripts has been shown to fluctuate in phase with the circadian rhythm, fluctuations at the protein level were less pronounced. This led us to hypothesize that the diurnal adaptation occurs at the level of higher organization of protein complexes. Therefore, we probed the abundance and constituency of S. elongatus protein complexes during the day and night. Following several well-known complexes such as the RNA polymerase, the ribosome and photosynthetic protein complexes, we observe for the first time that these complexes change not only in abundance but also in constituency. Therefore, we conclude that the dynamic assembly of protein complexes is indeed also a key-player in the processes governing the diurnal rhythm. SIGNIFICANCE: The succession of day and night periods imposes drastic changes in all living organisms. Cyanobacteria produce their energy through photosynthesis and are therefore strongly influenced by diurnal rhythms. The cyanobacteria, Synechococcus elongatus PCC 7942 (S. elongatus), also exhibit a self-sustained biological clock. The connection between the central circadian oscillator and its output to the rest of the cell is not completely known. It has been shown that the expression of many gene transcripts heavily fluctuates in phase with the circadian rhythm; however, our recent global proteomics investigation revealed that the diurnal fluctuations seemed to be less pronounced at the protein level. As many known regulatory functions depend on protein-protein interactions (PPIs) and/or protein assemblies and the fact that so few fluctuations in protein abundances were observed earlier, here we investigated the diurnal adaptation at the level of dynamic changes in protein assembly. The paper demonstrates that the combination of native protein complex fractionation and high-resolution proteomics provides insight in the regulation of megadalton protein assemblies in cyanobacteria, including the ribosomal and photosynthetic complexes. The differences observed between the light and dark conditions in these complexes indicate a cyclic regulation of essential cellular processes