RESUMO
The control of microbial infections is critical for the preparation of biological media including water to prevent lethal septic shock. Sepsis is one of the leading causes of death in the United States. More than half a million patients suffer from sepsis every year. Both gram-positive and gram-negative bacteria are responsible for septic infection by the most common organisms i.e., Escherichia coli and Pseuodomonas aeruginosa. The bacterial cell membrane releases negatively charged endotoxins upon death and enzymatic destruction, which stimulate antigenic response in humans to gram-negative infections. Several methods including distillation, ethylene oxide treatment, filtration and irradiation have been employed to remove endotoxins from contaminated samples, however, the reduction efficiency remains low, and presents a challenge. Polymer nanoparticles can be used to overcome the current inability to effectively sequester endotoxins from water. This process is termed endotoxin hitchhiking. The binding of endotoxin on polymer nanoparticles via electrostatic and hydrophobic interactions offers efficient removal from water. However, the effect of polymer nanoparticles and its surface areas has not been investigated for removal of endotoxins. Poly(ε-caprolactone) (PCL) polymer was tested for its ability to effectively bind and remove endotoxins from water. By employing a simple one-step phase separation technique, we were able to synthesize PCL nanoparticles of 398.3 ± 95.13 nm size and a polydispersity index of 0.2. PCL nanoparticles showed â¼78.8% endotoxin removal efficiency, the equivalent of 3.9 × 10(5) endotoxin units (EU) per ml. This is 8.34-fold more effective than that reported for commercially available membranes. Transmission electron microscopic images confirmed binding of multiple endotoxins to the nanoparticle surface. The concept of using nanoparticles may be applicable not only to eliminate gram-negative bacteria, but also for any gram-positive bacteria, fungi and parasites.
RESUMO
BACKGROUND: Sudden and unexpected postnatal collapse (SUPC) of a healthy newborn infant is a rare event, which carries a high risk of mortality and significant neurodisability in survivors. An underlying condition can be found in 60% of cases who undergo detailed postmortem but in the remainder there are important associations with prone position, breast feeding and primiparous status. The authors undertook a prospective study to ascertain the population incidence of SUPC in the UK. METHODS: Cases were referred through the British Paediatric Surveillance Unit reporting scheme over a 13-month period. Infants were at ≥37 weeks of gestation, had an Apgar score of ≥8 at 5 min, collapsed within 12 h in hospital requiring positive pressure ventilation and either died or received ongoing intensive care. Data were collected on maternal and infant characteristics, clinical investigations and 1-year outcome. FINDINGS: 45 cases were reported, an incidence of 0.05/1000 live births of whom 12 infants died. In 15/45 infants, an underlying disease/abnormality was determined. In 30/45 cases (0.035/1000 live births), no such cause was found, but in 24, the clinical/pathological diagnosis was airway obstruction during breast feeding or in prone position. Mothers were commonly primiparous and unattended by clinical staff before collapse was recognised. Approach to investigation was highly disparate and frequently very limited. Of the 30 infants with no underlying disease/abnormality, 22 (73%) developed a postasphyxial encephalopathy and 10 had a poor outcome (33%)--5 died and 5 had neurological sequelae at 1 year. INTERPRETATION: SUPC is rare in any one centre and there is no standard approach to investigation. In those cases where collapse is not due to an underlying abnormality, breast feeding and prone position are important associations. Guidelines for safe postnatal care of infants should include appropriate vigilance of infants particularly where mothers are primiparous or where ability to assess the baby may be impaired.
