Additive effects of thermal injury and infection on gut permeability.

OBJECTIVE: To determine the effects of burn size and burn wound infection on gut permeability to the macromolecule polyethylene glycol 3350 (PEG 3350; molecular weight, 3350 d). DESIGN: Randomized, controlled study using 36 male Sprague-Dawley rats. SETTING: Hospital research laboratory. INTERVENTIONS: Animals received scald burns to 0%, 20%, or 35% of their total body surface area. Half of the animals in each group were infected with Pseudomonas aeruginosa. MAIN OUTCOME MEASURES: Gut permeability was measured using the intestinal absorption and renal excretion of enterally administered PEG 3350 and mannitol (molecular weight, 182 d). RESULTS: There were dramatic increases in PEG 3350 excretion and in the PEG 3350/mannitol ratios (P = .0001 in both instances) that were seen in relation to burn size. Significant increases in PEG 3350 excretion and in the PEG 3350/mannitol ratios (P = .017 and P = .045, respectively) were also seen in animals in which infection was present. This was in addition to the effects of burn size already noted. CONCLUSIONS: A direct relationship between gut permeability and the extent of burn injury was found, which is consistent with the results from a previous study in humans. In addition, this study found that further separate increases in gut permeability occur in the presence of P aeruginosa in burn wound infections.

Is immediate chest radiograph necessary after central venous catheter placement in a surgical intensive care unit?

BACKGROUND: Current standard of care dictates that central venous catheter (CVC) insertion should be followed by an immediate chest radiograph to confirm appropriate position and rule out complications. We hypothesized that a subset of monitored intensive care unit patients exists that is at low risk for complications and might safely have radiographic evaluation of line placement deferred until the next scheduled radiograph. METHODS: Data regarding patient and procedural characteristics were obtained prospectively for 184 CVC placed between March 1, 1998, and June 30, 1999. Retrospective data regarding complications were obtained by chart review for an additional 174 CVC placed during the study period but for which data sheets were not completed. All procedures were followed by chest radiography. RESULTS: We documented a complication rate of 9% with the vast majority (25 of 31, 81%) of complications consisting of incorrect positioning. The number of needle passes was greater in the group suffering pneumothorax and arterial puncture than the uncomplicated group (5.6 versus 1.9, P = 0.008). "Straightforward" operator gestalt (P = 0.04) and number of needle passes <3 (P = 0.03) were factors correlating with the absence of complications. These factors had negative predictive values of 94% and 96%, respectively. CONCLUSION: Placement of CVC is safe in experienced hands. In monitored intensive care unit patients who undergo a "straightforward" procedure with <3 needle passes, chest radiograph can be safely deferred until the next scheduled examination.

Laparoscopic treatment of post renal transplant lymphoceles.

BACKGROUND: Traditionally, a post transplant lymphocele (PTL) is drained by widely opening the wall connecting the lymphocele cavity to the intraperitoneal space via laparotomy. We hypothesize that laparoscopic techniques can be effectively used for the treatment of PTL. METHODS: Patients requiring intervention for PTL between 1993 and 2002 were identified via a retrospective review. Results of drainage via laparotomy and laparoscopy were compared. RESULTS: During the study period 685 renal transplants (391 cadaveric, 294 living) were performed. The incidence of lymphocele was 5% [34/685 (36 cases)]. The indications for surgical drainage were local symptoms (69%), graft dysfunction (14%), or both (17%). The mean time to surgical therapy was 4.9 months. Laparoscopic drainage was performed in 25 patients (74%) and open drainage in 9 patients (26%). Open procedures were performed in cases for: previous abdominal surgery (5), undesirable lymphocele characteristics or location (2), or with concomitant open procedures (3). There were no conversions or operative complications in either group. There was no difference in operative time for the laparoscopic group vs the open group (108 +/- 6 vs 123 +/- 18 min, p = 0.8). Hospital stay was significantly shorter for the laparoscopic group (1.7 +/- 0.8 vs 3.8 +/- 1.0, p = 0.0007), with 88% of laparoscopic patients being either overnight admissions or same day surgery. Two patients (5%) developed symptomatic recurrences requiring reoperation [1 laparoscopic (4%), 1 open (10%)]. CONCLUSIONS: Laparoscopic fenestration of a peritransplant lymphocele is a safe and effective treatment. The large majority of patients treated with laparoscopic fenestration were discharged within one day of surgery. Unless contraindications exist, laparoscopy should be considered first-line therapy for the surgical treatment of posttransplant lymphocele.

The determination of ice composition with instruments on cometary landers.

The determination of the composition of materials that make up comets is essential in trying to understand the origin of these primitive objects. The ices especially could be made in several different astrophysical settings including the solar nebula, protosatellite nebulae of the giant planets, and giant molecular clouds that predate the formation of the solar system. Each of these environments makes different ices with different composition. In order to understand the origin of comets, one needs to determine the composition of each of the ice phases. For example, it is of interest to know that comets contain carbon monoxide, CO, but it is much more important to know how much of it is a pure solid phase, is trapped in clathrate hydrates, or is adsorbed on amorphous water ice. In addition, knowledge of the isotopic composition of the constituents will help determine the process that formed the compounds. Finally, it is important to understand the bulk elemental composition of the nucleus. When these data are compared with solar abundances, they put strong constraints on the macro-scale processes that formed the comet. A differential scanning calorimeter (DSC) and an evolved gas analyzer (EGA) will make the necessary association between molecular constituents and their host phases. This combination of instruments takes a small (tens of mg) sample of the comet and slowly heats it in a sealed oven. As the temperature is raised, the DSC precisely measures the heat required, and delivers the gases to the EGA. Changes in the heat required to raise the temperature at a controlled rate are used to identify phase transitions, e.g., crystallization of amorphous ice or melting of hexagonal ice, and the EGA correlates the gases released with the phase transition. The EGA consists of two mass spectrometers run in tandem. The first mass spectrometer is a magnetic-sector ion-momentum analyzer (MAG), and the second is an electrostatic time-of-flight analyzer (TOF). The TOF acts as a detector for the MAG and serves to resolve ambiguities between fragments of similar mass such as CO and N2. Because most of the compounds of interest for the volatile ices are simple, a gas chromatograph is not needed and thus more integration time is available to determine isotopic ratios. A gamma-ray spectrometer (GRS) will determine the elemental abundances of the bulk cometary material by determining the flux of gamma rays produced from the interaction of the cometary material with cosmic ray produced neutrons. Because the gamma rays can penetrate a distance of several tens of centimeters a large volume of material is analyzed. The measured composition is, therefore, much more likely to be representative of the bulk comet than a very small sample that might have lost some of its volatiles. Making these measurements on a lander offers substantial advantages over trying to address similar objectives from an orbiter. For example, an orbiter instrument can determine the presence and isotopic composition of CO in the cometary coma, but only a lander can determine the phase(s) in which the CO is located and separately determine the isotopic composition of each reservoir of CO. The bulk composition of the nucleus might be constrained from separate orbiter analyses of dust and gas in the coma, but the result will be very model dependent, as the ratio of gas to dust in the comet will vary and will not necessarily be equal to the bulk value.

Augmentation of myocardial transfection using TerplexDNA: a novel gene delivery system.

Gene therapy is a potential new strategy for the treatment of cardiovascular disease. The most efficacious method of gene delivery remains a key hurdle to effective gene therapy. We present the application of a novel, nonviral gene delivery system (TerplexDNA) to augment myocardial transfection. The hearts of New Zealand white rabbits were injected with reporter genes, luciferase cDNA or beta-galactosidase cDNA, either as naked plasmid DNA or plasmid DNA complexed with stearyl-poly(L-lysine)-low density lipoprotein (TerplexDNA). Three day left heart myocardial cell lysates produced 44571 +/- 8730 RLU (RLU = total light units/mg protein) for the TerplexDNA luciferase rabbits versus 1638 +/- 567 RLU for the naked luciferase rabbits (P = 0.002). Thirty days after injection, myocardial lysates produced 677 +/- 52 RLU for the TerplexDNA luciferase hearts versus 18 +/- 3 RLU for the naked luciferase hearts (P = 0.002). Histologic analysis of the hearts transfected with beta-galactosidase showed that TerplexDNA increased the area and depth of transfection compared with the naked plasmid DNA alone. The hearts of Sprague-Dawley rats were injected in a similar fashion and analyzed at 1, 3, 5, 10, 15, 25 and 30 days after injection. The naked luciferase injected hearts showed transient elevation of luciferase activity to day 5 but fell back to baseline levels after that time-point. The TerplexDNA luciferase injected hearts had significantly elevated luciferase activity to 30 days. The Terplex gene delivery system significantly augments myocardial transfection compared with a naked plasmid DNA system alone. The advantage in transfection efficiency appears to be related to the unique properties of the TerplexDNA carrier molecule. The TerplexDNA delivery system represents a novel means to augment transfection of the myocardium.