Anaerobic benzene oxidation coupled to nitrate reduction in pure culture by two strains of Dechloromonas.

Benzene contamination is a significant problem. It is used in a wide range of manufacturing processes and is a primary component of petroleum-based fuels. Benzene is a hydrocarbon that is soluble, mobile, toxic and stable, especially in ground and surface waters. It is poorly biodegraded in the absence of oxygen. However, anaerobic benzene biodegradation has been documented under various conditions. Although benzene biomineralization has been demonstrated with nitrate, Fe(III), sulphate or CO2 as alternative electron acceptors, these studies were based on sediments or microbial enrichments. Until now there were no organisms in pure culture that degraded benzene anaerobically. Here we report two Dechloromonas strains, RCB and JJ, that can completely mineralize various mono-aromatic compounds including benzene to CO2 in the absence of O2 with nitrate as the electron acceptor. This is the first example, to our knowledge, of an organism of any type that can oxidize benzene anaerobically, and we demonstrate the potential applicability of these organisms to the treatment of contaminated environments.

Predictors of acute respiratory failure after bone marrow transplantation in children.

OBJECTIVE: To determine factors associated with acute respiratory failure after bone marrow transplantation which can be identified before the onset of lung disease. DESIGN: Population-based, retrospective study. SETTING: A referral-based pediatric intensive care unit and bone marrow transplant center. PATIENTS: Thirty-nine patients with lung disease (abnormal chest radiograph or a need for supplemental oxygen) were identified from a group of 318 pediatric bone marrow transplant patients from 1978 to 1988. Thirty-four of 39 patients with complete data were further classified into patients with mild lung disease (recovery without needing endotracheal intubation, n = 16) and patients with acute respiratory failure (requirement for endotracheal intubation, n = 18). INTERVENTIONS: Regression analyses were performed to define risk factors for development of respiratory failure (multivariate logistic regression) and for a shortened interval between the identification of lung disease and respiratory failure (Cox proportional hazards analysis). MEASUREMENTS AND MAIN RESULTS: Ninety-three percent (15/16) of patients with mild lung disease survived. Conversely, only 9% (2/23) of patients with respiratory failure survived. Predictors of respiratory failure included graft vs. host disease (odds ratio 28.3, 95% confidence interval 1.9-421, p = .015), a prelung disease (baseline) circulating creatinine concentration of > 1.5 mg/dL (> 132.6 mumol/L) (odds ratio 28.4, 95% confidence interval 1.4-577, p = .029), and male gender (odds ratio 14.6, 95% confidence interval 1-210, p = .049). Predictors of a shortened time to onset of respiratory failure included baseline serum creatinine value of > 1.5 mg/dL (> 132.6 mumol/L) (hazard ratio 6.2, 95% confidence interval 1.5-26.5, p = .013) and baseline total bilirubin concentration > 1.4 mg/dL (> 23.9 mumol/L) (hazard ratio 4.5, 95% confidence interval 0.98-20.7, p = .053). The median time to onset of respiratory failure was 4 days in patients with baseline creatinine values > or = 1.5 mg/dL (> 132.6 mumol/L) and 5 days in patients with baseline bilirubin concentrations > or = 1.4 mg/dL (> 23.9 mumol/L) vs. > 26 days in patients with creatinine < 1.5 mg/dL (< 132.6 mumol/L) and > 29 days in patients with bilirubin < 1.4 mg/dL (< 23.9 mumol/L) (Kaplan-Meier analysis). CONCLUSIONS: Renal and liver dysfunction preceded clinical evidence of lung disease in bone marrow transplant patients who developed respiratory failure. Lung disease leading to respiratory failure and adult respiratory distress syndrome appears to develop as one component of the multiple organ failure syndrome in pediatric bone marrow transplant patients.

Impairment of cerebral autoregulation during extracorporeal membrane oxygenation in newborn lambs.

This study was designed to evaluate the effect of normothermic partial bypass, or venoarterial extracorporeal membrane oxygenation (ECMO), on cerebral autoregulation. Fourteen newborn lambs, 1-7 d of age, were randomized into two groups: control (ligation of right carotid artery and jugular vein without ECMO; n = 7) and ECMO (ligation with placement on routine venoarterial ECMO at 120-150 mL/kg/min; n = 7). After 1 h of ECMO or stabilization in controls, cerebral autoregulation was evaluated by lowering cerebral perfusion pressure (CPP) by increasing intracranial pressure through infusion of artificial cerebrospinal fluid into the lateral ventricle. Four ranges of CPP were evaluated: 1) baseline, 2) 55-40, 3) 39-25, and 4) < 25 mm Hg. In ECMO animals, cerebral blood flow (CBF) decreased from baseline (39 +/- 7 mL/100 g/min) to 23 +/- 7 and 12 +/- 2 at CPP of 39-25 and < 25 mm Hg. In the control group, CBF was unchanged from baseline (48 +/- 11 mL/100 g/min) until CPP was < 25 mm Hg, at which time it decreased to 27 +/- 16 mL/100 g/min. Cerebral oxygen consumption decreased from baseline (4.2 +/- 1.1 mL/100 g/min) to 4.0 +/- 0.7 and 3.2 +/- 1.3 mL/100 g/min at CPP of 39-25 and < 25 mm Hg, respectively, in the ECMO group. In the control group, cerebral oxygen consumption was unchanged from baseline (4.2 +/- 1.1 mL/100 g/min) until CPP was reduced to < 25 mm Hg (3.2 +/- 1.3 mL/100 g/min). When CBF autoregulation was altered, i.e. when total CBF decreased, right-left hemispheric CBF differences were noted in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Preinduction of anesthesia in children with rectally administered midazolam.

The authors evaluated the efficacy of rectally administered midazolam for preinduction (i.e., premedication/induction) of anesthesia in 67 pediatric patients, ASA physical status 1 or 2, undergoing a variety of elective surgical procedures. In phase 1, 41 children weighing 12 +/- 3 kg (range 7-20 kg) and 31 +/- 16 months (range 8-67 months) of age (mean +/- SD) received midazolam, 0.4-5.0 mg.kg-1, in an attempt to produce unconsciousness. Only one child lost consciousness (4.5 mg.kg-1). However, at all doses, inhalational induction of anesthesia was facilitated because children were tranquil and calmly separated from their parent(s). There were no clinically significant changes in arterial blood pressure, heart rate, oxyhemoglobin saturation, and end-tidal carbon dioxide concentration, 10 min after drug administration. In phase 2, 26 children weighing 17 +/- 4 kg (range 10-26 kg) and 44 +/- 19 months (range 17-84 months) months of age undergoing tonsil and/or adenoid surgery were studied to determine the optimal sedative dose of rectally administered midazolam. Patients received 0.3, 1.0, 2.0, or 3.0 mg.kg-1 of midazolam in a randomized, double-blind fashion. One third (3 of 9) of patients receiving 0.3 mg.kg-1 struggled during mask induction. All patients receiving greater than or equal to 1.0 mg.kg-1 were adequately sedated (P less than 0.008). Discharge from the postanesthesia care unit (PACU), however, was delayed (greater than 60 min) in children receiving greater than or equal to 2.0 mg.kg-1 (P less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)