Chylothorax in children with congenital heart disease: incidence of thrombosis.

Postoperative chylothorax is a frequently encountered pathology occurring in up to 4% of patients undergoing surgery for repair of congenital heart disease. Symptomatic thrombosis is associated with chylothorax and may contribute to its severity and duration. Furthermore, vessel thrombosis resulting in persistent vessel occlusion may impede future treatments, diagnostic studies and cardio-surgical interventions. The objective of this study was to determine the incidence of upper system thrombosis in pediatric congenital heart patients with confirmed chylothorax with ultrasound screening of all patients diagnosed with chylothorax. All pediatric patients with confirmed with chylothorax underwent doppler ultrasound of the upper venous system as per hospital standard. This retrospective cohort study enrolled all children between February 1, 2010-August 2012, post cardiac surgery with confirmed chylothorax to determine the incidence of all thrombosis. There were 1396 children who underwent 1396 cardiac surgical procedures during the study time with 760 undergoing cardiopulmonary bypass. Development of chylothorax occurred in 54 of 1396, 3.9% (95%CI 3.0;5.0) procedures in all children. In those children with chylothorax, 28 of 54 episodes, 51.8% (95%CI 38.9;64.6) had confirmed VTE. The 51.8% incidence in this study demonstrates a 2.6 fold increase in risk of thrombosis compared to 20% in children with heart disease and central venous lines and may result in serious clinical consequences. The contribution of upper venous system thrombosis to chylothorax is unknown. Often, clinical suspicion of chylothorax exists, however the lack of a standardized approach to objective diagnosis results in delayed confirmation. Approaches to therapy either treatment of confirmed thrombosis or prevention of thrombosis in patients with chylothorax require formal evaluation. Future studies are urgently needed.

Assessing the role of Pseudomonas aeruginosa surface-active gene expression in hexadecane biodegradation in sand.

Low pollutant substrate bioavailability limits hydrocarbon biodegradation in soils. Bacterially produced surface-active compounds, such as rhamnolipid biosurfactant and the PA bioemulsifying protein produced by Pseudomonas aeruginosa, can improve bioavailability and biodegradation in liquid culture, but their production and roles in soils are unknown. In this study, we asked if the genes for surface-active compounds are expressed in unsaturated porous media contaminated with hexadecane. Furthermore, if expression does occur, is biodegradation enhanced? To detect expression of genes for surface-active compounds, we fused the gfp reporter gene either to the promoter region of pra, which encodes for the emulsifying PA protein, or to the promoter of the transcriptional activator rhlR. We assessed green fluorescent protein (GFP) production conferred by these gene fusions in P. aeruginosa PG201. GFP was produced in sand culture, indicating that the rhlR and pra genes are both transcribed in unsaturated porous media. Confocal laser scanning microscopy of liquid drops revealed that gfp expression was localized at the hexadecane-water interface. Wild-type PG201 and its mutants that are deficient in either PA protein, rhamnolipid synthesis, or both were studied to determine if the genetic potential to make surface-active compounds confers an advantage to P. aeruginosa biodegrading hexadecane in sand. Hexadecane depletion rates and carbon utilization efficiency in sand culture were the same for wild-type and mutant strains, i.e., whether PG201 was proficient or deficient in surfactant or emulsifier production. Environmental scanning electron microscopy revealed that colonization of sand grains was sparse, with cells in small monolayer clusters instead of multilayered biofilms. Our findings suggest that P. aeruginosa likely produces surface-active compounds in sand culture. However, the ability to produce surface-active compounds did not enhance biodegradation in sand culture because well-distributed cells and well-distributed hexadecane favored direct contact to hexadecane for most cells. In contrast, surface-active compounds enable bacteria in liquid culture to adhere to the hexadecane-water interface when they otherwise would not, and thus production of surface-active compounds is an advantage for hexadecane biodegradation in well-dispersed liquid systems.

Hypoglycaemia in spinal muscular atrophy.

Repeated episodes of hypoglycaemia were observed in two girls with spinal muscular atrophy. During a 12 h fast blood glucose fell to 3.4 and 2.7 mmol/L, respectively. One girl developed hypoglycaemia and ketonuria. Reduced gluconeogenesis was probably the cause of hypoglycaemia in these patients who had a muscle mass of about 10% of bodyweight (normal 30-40%). Hypoglycaemia must be suspected and treated when patients with severe muscle wasting due to chronic neuromuscular disorders are admitted comatose. In our experience this condition is often regarded as respiratory insufficiency.

Iron kinetics effects of 88 millirads. Partial-versus-total body X-irradiation.

Rats were irradiated with one tibia shielded (95% marrow exposure), total body exposed (TBI, 100%), and only one tibia exposed (5%), or they were sham irradiated (SI, 0%). Plasma Fe-59 clearance time (T1/2) and Fe-59 content ratio in the right and left tibia (RT/LT) were assayed to determine the erythroid activity of the overall marrow of the animals and the relative marrow activity in the exposed and shielded tibias, respectively. When a major fraction of the overall marrow was shielded or irradiated, the overall erythroid activity levels were identical to those of the SI and TBI animals, respectively. Interestingly, enhanced normoblastosis was observed in the marrow of the exposed tibia of individual animals exhibiting normal erythroid activity in 95% of the marrow. Conversely, localized marrow with normal erythroid activity was found in a shielded tibia of individual rats, demonstrating an enhanced erythroid activity in a major fraction of the total body. It was concluded that 88 mrad can alter marrow functions in a small isolated skeletal region as effectively as in the whole body, and tandem assays of the Fe-59 T1/2 and Fe-59 RT/LT can facilitate ultra-low-dose X-ray studies involved with partial body exposures.

The effects of low dose (less than 1 rad) X-rays on the erythropoietic marrow.

Adult female Sprague-Dawley rats were exposed (200 kvp X-rays) to whole body doses of 22-1320 mrad and examined for changes in the level of red blood cell precursors (RBCp) in the marrow at 5-30 weeks post-irradiation, under nonbled and phlebotomy-induced anemic stress conditions. Increases in the RBCp %, RBCp/mg marrow, and RBCp/skeleton under nonbled conditions, and a suppressed erythroid response to an induced anemia, were found after acute doses in the range of at least 70 mrad. Dosages of 22 or 44 mrad that induced no measurable changes when applied only once were found to be effective when they were employed 4 or 2 times/week, respectively. The results suggested the presence of a linear-quadratic dose-response relationship in which the quadratic function exists between 88 and 981 mrad, and the linear dependency, below 88 mrad.

Radioprotection in E. coli by an agent from M. radiodurans.

An agent extracted from the radioresistant bacterium M. radiodurans was found to protect several strains of E. coli from X-radiation. Optimal radioprotection was observed when the repair-proficient B/r strain was irradiated in the presence of the agent under hypoxic conditions. It is proposed that this agent acts to modify damage incurred in the presence of reduced oxygen concentrations so that this damage might be subsequently repaired.

Respiratory activity as a determinant of radiation survival response.

Respiration is depressed in irradiated bacteria reaching a minimum level in most strains at 1-3 h after exposure when incubated in growth medium. Since a delay in response is observed, direct action on respiratory enzymes is unlikely. The dosage response of respiration varies widely in the strains studied with Do's from 15 kR for Escherichia coli BS-1 to 1200 kR for Micrococcus radiodurans. All strains exhibit two-component dosage-response curves. Escherichia coli BS-1 uniquely possesses a positive-sloped second component suggesting a major disruption of respiratory control. A relationship exists between the responses of respiration and survival to a 50-kR exposure in the strains studied. When E. coli B/r is grown in 0.4% glucose reaching a pH of 5.3, a condition known to increase radiation survival considerably, a large increase in radioresistance of respiration is found. 2-Mercaptoethylamine (MEA), a radioprotective agent, also produces proportionate radioprotection of respiration and survival. In M. radiodurans protection is afforded to respiration at doses which produce no measurable effect on survival. These facts suggest that respiration is a major factor in influencing cell survival and may be the principal mechanism through which chemical agents modify radiation response.

Deoxyribonucleic acid-protein ratio and radioresistance in Micrococcus radiodurans.

Cessation of exponential growth of Micrococcus radiodurans heightens X-radioresistance while either increasing or decreasing the deoxyribonucleic acid-protein ratio.

Radioresistance of Micrococcus radiodurans during the growth cycle.

Micrococcus radiodurans, irradiated aerobically in phosphate buffer, exhibits a phasic response to x-irradiation during its growth cycle. The culture progresses from a relatively sensitive state during the exponential portion of the growth cycle to a highly resistant state during the stationary phase. The shift in resistance is characterized by a marked extension of the shoulder of the survival curve and a threefold increase in the LD99 from 250 kR to over 700 kR. The resistant state appears to be a metastable condition, readily induced in exponential-phase cultures and easily reversed in stationary-phase cultures. Similar variations are not elicited in response to ultraviolet irradiation. The phasic response does not appear to be the result of a low-molecular-weight extractable sulfhydryl radioprotective agent.