Method validation and environmental monitoring of triethanolamine ester quaternary ammonium compounds

In this study water and sediment samples, collected from the River Nene (Northamptonshire) at several sites in the vicinity of the Great Billing sewage treatment plant (STP), were analysed for triethanolamine quaternary compounds (TEAQ, ester quats). A method was developed using liquid chromatography tandem mass spectrometry (LC/MS/MS) with a electrospray ionisation source (ESI). Ten components were determined using a characterised commercial sample of Tallow TEAQ as a standard. To our knowledge this is the first time environmental concentrations of a wide spectrum of individual homologues of TEAQ have been reliably quantified covering a broad range of environmental matrices (STP influent, STP effluent, surface waters and sediments), due to the challenging nature of the analytical method. The method featured novel solutions for the determination of long and multiple chain length alkyl quats, controlling loss processes, background contamination and chromatographic performance. TEAQ compounds were found to be highly removed in the sewage treatment plant resulting in low effluent concentrations. Low concentrations in both river water and sediment samples were found also. In many cases levels were below the Method Detection Limit (MDL). In river water samples, mean values of TEAQ compounds found were 210-398 ng/L for C16:0/C18:0 TEAQ diester and 126-287 ng/L for C18:0/C18:0 TEAQ diester. River sediment was found to contain mean TEAQ levels of 7.07-12.5, 19.7 to 40.3 and 7.04-35.1 μg/kg dry weight for C16:0/C16:0, C16:0/C18:0, and C18:0/C18:0 TEAQ, respectively. At Great Billing STP monoesters and diesters of TEAQ were shown to be efficiently removed (>97 and 99 %, respectively), although limited samples were taken on this occasion.

X-ray micro-diffraction studies on biological samples at the BioCAT Beamline 18-ID at the Advanced Photon Source

The small source sizes of third-generation synchrotron sources are ideal for the production of microbeams for diffraction studies of crystalline and non-crystalline materials. While several such facilities have been available around the world for some time now, few have been optimized for the handling of delicate soft-tissue specimens under cryogenic conditions. Here the development of a new X-ray micro-diffraction instrument at the Biophysics Collaborative Access Team beamline 18-ID at the Advanced Photon Source, and its use with newly developed cryo-diffraction techniques for soft-tissue studies, are described. The combination of the small beam sizes delivered by this instrument, the high delivered flux and successful cryo-freezing of rat-tail tendon has enabled us to record data to better than 4 Å resolution. The ability to quickly raster scan samples in the beam allows selection of ordered regions in fibrous samples for markedly improved data quality. Examples of results of experiments obtainable using this instrument are presented.

Multi-wavelength anomalous diffraction using medium-angle X-ray solution scattering (MADMAX)

Proteins are dynamic molecules whose function in virtually all biological processes requires conformational motion. Direct experimental probes of protein structure in solution are needed to characterize these motions. Anomalous scattering from proteins in solution has the potential to act as a precise molecular ruler to determine the positions of specific chemical groups or atoms within proteins under conditions in which structural changes can take place free from the constraints of crystal contacts. In solution, anomalous diffraction has two components: a set of cross-terms that depend on the relative location of the anomalous centers and the rest of the protein, and a set of pure anomalous terms that depend on the distances between the anomalous centers. The cross-terms are demonstrated here to be observable and to provide direct information about the distance between the anomalous center and the center of mass of the protein. The second set of terms appears immeasurably small in the context of current experimental capabilities. Here, we outline the theory underlying anomalous scattering from proteins in solution, predict the anomalous differences expected on the basis of atomic coordinate sets, and demonstrate the measurement of anomalous differences at the iron edge for solutions of myoglobin and hemoglobin.

WAXS studies of the structural diversity of hemoglobin in solution

Specific ligation states of hemoglobin are, when crystallized, capable of taking on multiple quaternary structures. The relationship between these structures, captured in crystal lattices, and hemoglobin structure in solution remains uncertain. Wide-angle X-ray solution scattering (WAXS) is a sensitive probe of protein structure in solution that can distinguish among similar structures and has the potential to contribute to these issues. We used WAXS to assess the relationships among the structures of human and bovine hemoglobins in different liganded forms in solution. WAXS data readily distinguished among the various forms of hemoglobins. WAXS patterns confirm some of the relationships among hemoglobin structures that have been defined through crystallography and NMR and extend others. For instance, methemoglobin A in solution is, as expected, nearly indistinguishable from HbCO A. Interestingly, for bovine hemoglobin, the differences between deoxy-Hb, methemoglobin and HbCO are smaller than the corresponding differences in human hemoglobin. WAXS data were also used to assess the spatial extent of structural fluctuations of various hemoglobins in solution. Dynamics has been implicated in allosteric control of hemoglobin, and increased dynamics has been associated with lowered oxygen affinity. Consistent with that notion, WAXS patterns indicate that deoxy-Hb A exhibits substantially larger structural fluctuations than HbCO A. Comparisons between the observed WAXS patterns and those predicted on the basis of atomic coordinate sets suggest that the structures of Hb in different liganded forms exhibit clear differences from known crystal structures.

Fast-scanning high-flux microprobe for biological X-ray fluorescence microscopy and microXAS

There is a growing interest in the biomedical community in obtaining information concerning the distribution and local chemical environment of metals in tissues and cells. Recently, biological X-ray fluorescence microscopy (XFM) has emerged as the tool of choice to address these questions. A fast-scanning high-flux X-ray microprobe, built around a recently commissioned pair of 200 mm-long Rh-coated silicon Kirkpatrick-Baez mirrors, has been constructed at BioCAT beamline 18ID at the Advanced Photon Source. The new optical system delivers a flux of 1.3 x 10(12) photons s(-1) into a minimum focal spot size of approximately 3-5 microm FWHM. A set of Si drift detectors and bent Laue crystal analyzers may be used in combination with standard ionization chambers for X-ray fluorescence measurements. BioCAT's scanning software allows fast continuous scans to be performed while acquiring and storing full multichannel analyzer spectra per pixel on-the-fly with minimal overhead time (<20 ms per pixel). Together, the high-flux X-ray microbeam and the rapid-scanning capabilities of the BioCAT beamline allow the collection of XFM and micro X-ray absorption spectroscopy (microXAS) measurements from as many as 48 tissue sections per day. This paper reports the commissioning results of the new instrument with representative XFM and microXAS results from tissue samples.

Dynamic multi-phase partitioning of decamethylcyclopentasiloxane (D5) in river water

The behaviour of decamethylcyclopentasiloxane (D5) in river water was evaluated by measuring concentration changes in open beakers. Effective values for the partition coefficient between organic carbon and water (K(OC)) were derived by least-squares optimisation of a dynamic model which accounted for partitioning between the sorbed and dissolved phases of D5, and for losses via volatilisation and hydrolysis. Partial mass transfer coefficients for volatilisation were derived from model fits to controls containing deionised water. Effective values of log (K(OC)) were between 5.8 and 6.33 (mean 6.16). These figures are higher than some other experimentally-derived values but much lower than those estimated from the octanol: water partition coefficient using single-parameter linear free energy relationships (LFERs). A poly-parameter LFER gave a predicted log (K(OC)) of 5.5. Differences in partitioning are believed to be due to the nature of the organic matter present. The new value for effective K(OC) was employed in a simple model of D5 behaviour in rivers to ascertain the extent to which a higher affinity for organic carbon would depress volatility. The results suggest that despite the revised K(OC) value, volatilisation of D5 remains a significant removal mechanism in surface waters.

The BioCAT undulator beamline 18ID: a facility for biological non-crystalline diffraction and X-ray absorption spectroscopy at the Advanced Photon Source

The 18ID undulator beamline of the Biophysics Collaborative Access Team at the Advanced Photon Source, Argonne, IL, USA, is a high-performance instrument designed for, and dedicated to, the study of partially ordered and disordered biological materials using the techniques of small-angle X-ray scattering, fiber diffraction, and X-ray absorption spectroscopy. The beamline and associated instrumentation are described in detail and examples of the representative experimental results are presented.

Hyperglycaemia is associated with fungaemia and an increased mortality rate in severely burned children

Background

Hyperglycaemia may have detrimental effects on immunity. The purpose of this study was to assess any relationship between hyperglycaemia and clinical outcome following injury.

Methods

The records of children with burns covering 60 per cent or more of the body surface admitted after 1996 were reviewed. Patients were categorized as having poor glucose control if 40 per cent or more of all plasma glucose determinations were 7·8 mmol l−1 or greater and were compared with patients with adequate glucose control (less than 40 per cent of glucose values 7·8 mmol l−1 or greater).

Results

Despite similar age, burn size and caloric intake, the extent and severity of hyperglycaemia was significantly greater in the 33 patients categorized as having poor glucose control than in the 25 patients with adequate glucose control. Patients with hyperglycaemia had a significantly higher proportion of blood cultures positive for yeast (mean(s.d.) 3·7(10·0) versus 0·1(0·7) per cent; P &lt; 0·05, Student's t test). Nine of 33 patients with persistent hyperglycaemia died, compared with only one of 25 with adequate glucose control (P ≤ 0·05, Fisher's exact test).

Conclusion

This association between hyperglycaemia, fungaemia and subsequent death in severely burned children may be related to a hyperglycaemia-induced deterioration in immune function. This suggests that aggressive manoeuvres to normalize plasma glucose may be warranted.

Superiority of oral ketamine as an analgesic and sedative for wound care procedures in the pediatric patient with burns

The management of pain and anxiety in pediatric patients with burns includes the challenge of striking a balance between inadequate versus excessive medication. Ketamine provides effective sedative, analgesic, and amnestic properties for children and has been used intravenously with good results. With its recent availability as an elixir, we speculated that ketamine given orally may provide effective analgesia and sedation during wound care procedures with a wide safety margin. To test this hypothesis, 19 pediatric patients with burns undergoing a wound care procedure were randomized to receive either ketamine oral suspension or 300 mg acetaminophen with codeine phosphate and diphenhydramine, our prior standard for analgesia and sedation. Intensity of pain was determined with use of a color slide algometer and demonstrated more than 400% reduction in pain with the use of ketamine (p < 0.05). The Ramsey scale was used to quantitate sedation and demonstrated that ketamine improved sedation by 360% (p < 0.05). These results substantiate improved analgesia and sedation with oral ketamine as compared to a commonly used narcotic and sedative in facilitating wound care procedures in pediatric patients with burns. These findings suggest that expanded use of ketamine oral suspension may be.

Unna's boot dressings facilitate outpatient skin grafting of hands

Present day economics have challenged health care providers to minimize the length of hospitalization without sacrificing quality of care. Within this context, the purpose of this study was to determine whether supporting the hand and wrist with an Unna's boot dressing (Medicopaste bandage; Graham-Field, Inc., Hauppauge, N.Y.) and splint, and covering the skin graft donor site with calcium alginate (Kaltostat; Calgon Vestal, St. Louis, Mo.), would allow successful outpatient skin grafting of burns to the upper extremity. Twelve patients with burns underwent debridement and split-thickness skin grafting on a total of 16 upper extremities with this method. Only patients who were otherwise healthy, had adequate home environments, and had burns limited to distal to the elbow were included for this initial trial. All skin graft donor sites were obtained from either the upper thigh or buttocks. Patients were discharged to home after 4 to 6 hours of observation and given amoxicillin for 5 days after surgery. Patients returned to the burn unit on the fifth postgrafting day for removal of the Unna's boot dressing, initiation of occupational therapy to the hands, and reapplication of a new calcium alginate dressing if needed. This and subsequent follow-up visits revealed a 95% or more take on all skin grafts, without any infectious complications. These results demonstrate the efficacy of Unna's boot support and calcium alginate dressings of donor sites in limited skin graft procedures. Furthermore, these results suggest that more extensive surgical debridements and skin graftings may be successfully shifted to outpatient procedures with use of these adjuvants.

Hyaluronic acid impedes reepithelialization of skin graft donor sites

Prior studies have suggested that hyaluronic acid (HA), a naturally occurring glycosaminoglycan, may accelerate the healing of superficial burn wounds. To objectively assess whether exogenous HA could accelerate the rate of healing and limit scar formation in superficial wounds, 11 patients with burn injuries who were undergoing skin grafting were given two separate skin graft donor sites of similar size and depth (1" x 1" x 0.016"). In a randomized, double-blind fashion, one of these partial-thickness wounds had repeated application with 1.5% HA; 100% glycerin, which served as a control of similar viscosity, was applied to the other wound. On alternating days, photographs were taken and then analyzed with computerized digital planimetry to objectively quantitate the rate of reepithelialization. In contrary to our hypothesis, HA significantly delayed wound healing compared to the glycerin control (time to > 95% reepithelialization: 10.3 +/- 2 days HA vs. 9.1 +/- 1.6 days control; mean +/- SD). Furthermore, no difference in the resultant scar at 6 weeks and at 3 months after wounding was evident. These results demonstrate that HA retards healing of partial thickness wounds in adults.

Thoracoscopic splanchnicectomy: technique and case report

Division of the greater and lesser splanchnic nerves using a thoracoscopic approach is presented. Splanchnicectomy has been described by several surgeons as a means of palliating chronic pancreatic pain caused by either alcohol-related chronic pancreatitis or pancreatic cancer. Thoracoscopy represents a minimally invasive approach to the splanchnic nerves. Current three-chip cameras enable a sixfold to eightfold magnification of intrathoracic structures, and the nerves are easily identified. The role of this operation in the thoracic surgeon's armamentarium awaits larger series of patients with longer follow-up.

Evaluation of calcium alginate for skin graft donor sites

Choosing the most appropriate wound dressing is of importance in optimizing healing and minimizing pain. Recent reports have suggested an improvement in wound healing with calcium alginate. To clinically evaluate this new dressing, 12 paired wounds were covered with either calcium alginate or scarlet red in seven patients with burns undergoing skin grafting. The rate of reepithelialization was assessed by optical planimetry for the calcium alginate and by time for sloughing of the scarlet red. This comparison failed to demonstrate objectively any difference in the rate of wound healing between these dressings; however, calcium alginate did significantly reduce the pain severity and was favored by the nursing personnel because of its ease of care. Thus calcium alginate does appear to have clinical advantages as a dressing for skin graft donor sites.

Comparison of complications during rehabilitation between conservative and early surgical management in thermal burns involving the feet of children and adolescents

To evaluate the long-term sequelae of early surgical management compared with conservative therapy, a retrospective review from January 1976 to December 1984 was undertaken. Through inspection of burn diagrams, 395 patients were identified with burns involving the foot. From 1976 through 1980, 109 patients were managed in a conservative fashion with topical antimicrobial therapy and delayed debridement and grafting; 36 of these patients with severe burns were managed with skeletal suspension. Between 1981 and 1984, 136 patients were treated with earlier surgical debridement and grafting; during this period, skeletal suspension was rarely used. No statistical difference was found in mortality, amputations, incidence of open wounds, development of contractures, or number of patients requiring reconstructive procedures between conservative and early excision therapy except in those children treated with skeletal suspension. Thus in burns involving the feet in children, early excision and grafting does not alter the resultant morbidity compared with conservative burn management.

Treatment of intestinal ischemia with oxygenated intraluminal perfluorocarbons

Liquid perfluorocarbons are biologically inert compounds capable of dissolving up to 40 percent oxygen by volume. This remarkable and reversible oxygen solubility has encouraged investigations into therapeutic application in situations where tissue oxygen delivery is impaired. One such setting is intestinal ischemia. Identically prepared devascularized segments of rat intestine were treated with either intraluminal oxygenated perfluorocarbon (perfluorotributylamine) or physiologic saline solution. After timed sacrifice, blinded quantitative histologic evaluation for ischemic injury was performed. The perfluorotributylamine treatment groups had histologic scores indicative of less severe injury between 1 and 4 hours. These scores achieved statistical significance (p less than 0.05). We conclude that intraluminal oxygenated perfluorocarbons have a significant protective effect in this model of intestinal ischemia. This quantitative analysis is unique and is an important aspect of the preclinical evaluation of the perfluorocarbon preparations.

Determinants of mortality in pediatric patients with greater than 70% full-thickness total body surface area thermal injury treated by early total excision and grafting

Recent advancements in burn care have improved the survival rates of victims with severe burn injuries. The total mortality rate in a series of 1,057 pediatric patients admitted to Shriners Burns Institute Galveston Unit between 1982 and 1986 was 2.7%. The burn size resulting in a 50% death rate was 95% of the total body surface area (TBSA). In this study 19 survivors and 13 nonsurvivors with greater than 70% full-thickness TBSA burn injuries were compared. All survivors were adequately resuscitated upon arrival 11% sustained an inhalation injury. Forty-six per cent of the nonsurvivors sustained an inhalation injury; 31% were not initially adequately resuscitated. The presence of preadmission shock and inhalation injury were early determinants of mortality with secondary renal, pulmonary, or cardiovascular collapse being the later predictors of mortality in these massively burned pediatric patients.

Comparative effects of dopamine, naloxone, and prostacyclin in the resuscitation of fecal-Escherichia coli peritonitis-induced septic shock in neonatal swine

To explain the high neonatal mortality from peritonitis-induced septic shock despite current resuscitation practices, the efficacy of dopamine, naloxone, and prostacyclin was evaluated in an experimental neonatal model. Hemodynamics were monitored and survival was measured in anesthetized neonatal swine, which were subjected to fatal fecal-Escherichia coli peritonitis-induced septic shock. All the animals received fluid resuscitation, antibiotics, and bicarbonate to correct acidosis. Pharmacologic resuscitation began when cardiac output dropped below baseline in the experimental groups. Although significant differences were observed between groups in cardiac output, mean arterial and mean pulmonary arterial pressures, left ventricular stroke work, stroke volume, and pulmonary vascular resistance indices (P less than 0.02), and each animal exhibited favorable hemodynamic responses during the first several hours of dopamine and naloxone infusion, these drugs failed to prolong survival. Also, 5 of the 9 naloxone-treated pigs (56%), died with histologically proven intestinal ischemia (P less than 0.02). Thus, dopamine, naloxone, and prostacyclin (at doses commonly recommended for the treatment of septic shock) fail to positively influence the fatal course of this condition, and the use of naloxone in this model is associated with profound intestinal ischemia.

The use of 5-(125I)iodo-2'-deoxyuridine for monitoring DNA synthesis in organ culture

5-[125I]iodo-2'-deoxyuridine (125IUdR) has been shown to be effective in monitoring DNA synthesis in murine tumour and human benign prostatic hyperplasia explants maintained in organ culture for 2 days, thus making possible the rapid screening of antitumour drugs. Uptake was linear for at least 24 hours in the case of the murine tumour and for 6 hours in the case of the prostate. Hydroxyurea almost completely blocked uptake by the murine tumour at doses above 10(-4) mole. Fluorodeoxyuridine (10(-6) mole) markedly increased the uptake of 125IUdR into the human prostate explants. Fixation of the murine tumour explants in alcoholic Bouin after culture did not alter the radioactive uptake and so routine histological examination of the tissue can be carried out after counting, which is a major advantage over [3H]thymidine.