Decreasing formalin concentration improves quality of DNA extracted from formalin-fixed paraffin-embedded tissue specimens without compromising tissue morphology or immunohistochemical staining.

Genomic technologies are increasingly used clinically for both diagnosis and guiding cancer therapy. However, formalin fixation can compromise DNA quality. This study aimed to optimise tissue fixation using normal colon, liver and uterus (n=8 each) by varying neutral buffered formalin (NBF) concentration (1%-5% w/v) and fixation time (24-48 hours). Fixation using 4% NBF improved DNA quality (assessed by qPCR) compared with routine (4% unbuffered formal saline-fixed) specimens (p<0.01). Further improvements were achieved by reducing NBF concentration (p<0.00001), whereas fixation time had no effect (p=0.110). No adverse effects were detected by histopathological or QuPath morphometric analysis. Immunohistochemistry for multicytokeratin and α-smooth muscle actin revealed no changes in staining specificity or intensity in any tissue other than on liver multicytokeratin staining intensity, where the effect of fixation time was more significant (p=0.0004) than NBF concentration (p=0.048). Thus, reducing NBF concentration can maximise DNA quality without compromising tissue morphology or standard histopathological analyses.

Carbon dioxide-catalyzed peroxynitrite reactivity - The resilience of the radical mechanism after two decades of research.

Peroxynitrite, ONOO-, formed in tissues that are simultaneously generating NO• and O2•-, is widely regarded as a major contributor to oxidative stress. Many of the reactions involved are catalyzed by CO2 via formation of an unstable adduct, ONOOC(O)O-, that undergoes O-O bond homolysis to produce NO2• and CO3•- radicals, whose yields are equal at about 0.33 with respect to the ONOO- reactant. Since its inception two decades ago, this radical-based mechanism has been frequently but unsuccessfully challenged. The most recent among these [Serrano-Luginbuehl et al. Chem. Res. Toxicol.31:721-730; 2018] claims that ONOOC(O)O- is stable, predicts a yield of NO2•/CO3•- of less than 0.01 under physiological conditions and, contrary to widely accepted viewpoints, suggests that radical generation is inconsequential to peroxynitrite-induced oxidative damage. Here we review the experimental and theoretical evidence that support the radical model and show this recently proposed alternative mechanism to be incorrect.

Oxidative Release of Copper from Pharmacologic Copper Bis(thiosemicarbazonato) Compounds.

Intracellular delivery of therapeutic or analytic copper from copper bis-thiosemicabazonato complexes is generally described in terms of mechanisms involving one-electron reduction to the Cu(I) analogue by endogenous reductants, thereby rendering the metal ion labile and less strongly coordinating to the bis-thiosemicarbazone (btsc) ligand. However, electrochemical and spectroscopic studies described herein indicate that one-electron oxidation of CuII(btsc) and ZnIIATSM (btsc = diacetyl-bis(4-methylthiosemicarbazonato)) complexes occurs within the range of physiological oxidants, leading to the likelihood that unrecognized oxidative pathways for copper release also exist. Oxidations of CuII(btsc) by H2O2 catalyzed by either myeloperoxidase or horseradish peroxidase, by HOCl and taurine chloramine (which are chlorinating agents generated primarily in activated neutrophils from MPO-catalyzed reactions), and by peroxynitrite species (ONOOH, ONOOCO2-) that can form under certain conditions of oxidative stress are demonstrated. Unlike reduction, the oxidative reactions proceed by irreversible ligand oxidation, culminating in release of Cu(II). 2-Pyridylazoresorcinol complexation was used to demonstrate that Cu(II) release by reaction with peroxynitrite species involved rate-limiting homolysis of the peroxy O-O bond to generate secondary oxidizing radicals (NO2•, •OH, and CO3•-). Because the potentials for CuII(btsc) oxidation and reduction are ligand-dependent, varying by as much as 200 mV, it is clearly advantageous in designing therapeutic methodologies for specific treatments to identify the operative Cu-release pathway.

Outcomes of Geriatric Trauma Patients on Preinjury Anticoagulation: A Multicenter Study.

Outpatient anticoagulation in the geriatric trauma patient is a challenging clinical problem. The aim of this study is to determine clinical outcomes associated with class of preinjury anticoagulants (PA) used by this population. This is a multicenter retrospective cohort study among four Level II trauma centers. A total of 1642 patients were evaluated; 684 patients were on anticoagulation and 958 patients were not. Patients on PA were compared with those who were not. Drug classes were divided into thromboxane A2 inhibitors, vitamin K factor-dependent inhibitors, antithrombin III activation, platelet P2Y12 inhibitors, and thrombin inhibitors. Multivariate regression was used to adjust for age, gender, race, mechanism of injury, and Injury Severity Score. No single or combination of anticoagulation agents had a significant association with mortality; however, there were positive trends toward increased mortality were noted for all antiplatelet groups involving thromboxane A2 inhibitors and platelet P2Y12 inhibitors classes. The likelihood of complications was significantly higher with platelet P2Y12 inhibitors adjusted odds ratio (aOR) 2.39 [95% confidence interval (CI) 1.32, 4.3]. The likelihood of blood transfusion was increased with vitamin K inhibitors aOR 2.89 (95% CI 1.3, 6.5), P2Y12 inhibitors aOR 2.76 (95% CI 1.12, 6.76), and combined thromboxane A2 and P2Y12 inhibitors aOR 2.89 (95% CI 1.13, 7.46). P2Y12 inhibitors were also more likely associated with traumatic brain injury aOR 2.16 (95% CI 1.01, 4.6). All classes of PA were associated with solid organ injury. There were no significant differences in the use of antiplatelet agents between patients with major indications for PA and those without major indications. Geriatric trauma patients on outpatient anticoagulants have a higher likelihood of developing complications, packed red blood cell transfusions, traumatic brain injury, and solid organ injury. Attention should be paid to patients on platelet P2Y12 inhibitors, vitamin K inhibitors, and thromboxane A2 inhibitor agents combined with platelet P2Y12 inhibitors. Opportunities exist to address the use of antiplatelet agents among patients without major indications to improve patient outcomes.

Benchmarking statewide trauma mortality using Agency for Healthcare Research and Quality's patient safety indicators.

BACKGROUND: Improving clinical outcomes of trauma patients is a challenging problem at a statewide level, particularly if data from the state's registry are not publicly available. Promotion of optimal care throughout the state is not possible unless clinical benchmarks are available for comparison. Using publicly available administrative data from the State Department of Health and the Agency for Healthcare Research and Quality (AHRQ) patient safety indicators (PSIs), we sought to create a statewide method for benchmarking trauma mortality and at the same time also identifying a pattern of unique complications that have an independent influence on mortality. METHODS: Data for this study were obtained from State of Florida Agency for Health Care Administration. Adult trauma patients were identified as having International Classification of Disease ninth edition codes defined by the state. Multivariate logistic regression was used to create a predictive inpatient expected mortality model. The expected value of PSIs was created using the multivariate model and their beta coefficients provided by the AHRQ. Case-mix adjusted mortality results were reported as observed to expected (O/E) ratios to examine mortality, PSIs, failure to prevent complications, and failure to rescue from death. RESULTS: There were 50,596 trauma patients evaluated during the study period. The overall fit of the expected mortality model was very strong at a c-statistic of 0.93. Twelve of 25 trauma centers had O/E ratios <1 or better than expected. Nine statewide PSIs had failure to prevent O/E ratios higher than expected. Five statewide PSIs had failure to rescue O/E ratios higher than expected. The PSI that had the strongest influence on trauma mortality for the state was PSI no. 9 or perioperative hemorrhage or hematoma. Mortality could be further substratified by PSI complications at the hospital level. CONCLUSIONS: AHRQ PSIs can have an integral role in an adjusted benchmarking method that screens at risk trauma centers in the state for higher than expected mortality. Stratifying mortality based on failure to prevent PSIs may identify areas of needed improvement at a statewide level.

Mechanistic Insight into Peroxydisulfate Reactivity: Oxidation of the cis,cis-[Ru(bpy)2(OH2)]2O(4+) "Blue Dimer".

One-electron oxidation of the µ-oxo dimer (cis,cis-[Ru(III)(bpy)2(OH2)]2O(4+), {3,3}) to {3,4} by S2O8(2-) can be described by three concurrent reaction pathways corresponding to the three protic forms of {3,3}. Free energy correlations of the rate constants, transient species dynamics determined by pulse radiolysis, and medium and temperature dependencies of the alkaline pathway all suggest that the rate-determining step in these reactions is a strongly nonadiabatic dissociative electron transfer within a precursor ion pair leading to the {3,4}|SO4(2-)|SO4(•-) ion triple. As deduced from the SO4(•-) scavenging experiments with 2-propanol, the SO4(•-) radical then either oxidizes {3,4} to {4,4} within the ion triple, effecting a net two-electron oxidation of {3,3}, or escapes in solution with ∼25% probability to react with additional {3,3} and {3,4}, that is, effecting sequential one-electron oxidations. The reaction model presented also invokes rapid {3,3} + {4,4} → 2{3,4} comproportionation, for which kcom ∼5 × 10(7) M(-1) s(-1) was independently measured. The model provides an explanation for the observation that, despite favorable energetics, no oxidation beyond the {3,4} state was detected. The indiscriminate nature of oxidation by SO4(•-) indicates that its fate must be quantitatively determined when using S2O8(2-) as an oxidant.

Imidazole catalyzes chlorination by unreactive primary chloramines.

Hypochlorous acid and simple chloramines (RNHCl) are stable biologically derived chlorinating agents. In general, the chlorination potential of HOCl is much greater than that of RNHCl, allowing it to oxidize or chlorinate a much wider variety of reaction partners. However, in this study we demonstrate by kinetic analysis that the reactivity of RNHCl can be dramatically promoted by imidazole and histidyl model compounds via intermediary formation of the corresponding imidazole chloramines. Two biologically relevant reactions were investigated--loss of imidazole-catalyzed chlorinating capacity and phenolic ring chlorination using fluorescein and the tyrosine analog, 4-hydroxyphenylacetic acid (HPA). HOCl reacted stoichiometrically with imidazole, N-acetylhistidine (NAH), or imidazoleacetic acid to generate the corresponding imidazole chloramines which subsequently decomposed. Chloramine (NH2Cl) also underwent a markedly accelerated loss in chlorinating capacity when NAH was present, although in this case N-α-acetylhistidine chloramine (NAHCl) did not accumulate, indicating that the catalytic intermediate must be highly reactive. Mixing HOCl with 1-methylimidazole (MeIm) led to very rapid loss in chlorinating capacity via formation of a highly reactive chlorinium ion (MeImCl(+)) intermediate; this behavior suggests that the reactive forms of the analogous imidazole chloramines are their conjugate acids, e.g., the imidazolechlorinium ion (HImCl(+)). HOCl-generated imidazole chloramine (ImCl) reacted rapidly with fluorescein in a specific acid-catalyzed second-order reaction to give 3'-monochloro and 3',5'-dichloro products. Equilibrium constants for the transchlorination reactions HOCl + HIm = H2O + ImCl and NH2Cl + HIm = NH3 + ImCl were estimated from the dependence of the rate constants on [HIm]/[HOCl] and literature data. Acid catalysis again suggests that the actual chlorinating agent is HImCl(+); consistent with this interpretation, MeIm markedly catalyzed fluorescein chlorination by HOCl. Time-dependent imidazole-catalyzed HPA chlorination by NH2Cl was also demonstrated by product analyses. Quantitative assessment of the data suggests that physiological levels of histidyl groups will react with primary chloramines to generate a flux of imidazole chloramine sufficient to catalyze biological chlorination via HImCl(+), particularly in environments that generate high concentrations of HOCl such as the neutrophil phagosome.

Geriatric outcomes for trauma patients in the state of Florida after the advent of a large trauma network.

BACKGROUND: Florida State has one of the largest geriatric populations in the United States. However, recent data show that up to the year 2010, geriatric trauma patients were least served by designated trauma centers (TCs). One existing TC and five provisional Level 2 TCs were combined to create a large-scale trauma network (TN). The new TCs were placed in those areas with the lowest ratios of TC to residents based on census data. The aim of this study was to measure the TN impact on the population of geriatric trauma patients. METHODS: Data from the Florida State Agency for Health Care Administration were used to determine mortality, length of stay, and complication rates for geriatric trauma patients (≥ 65 years). The potential effect of the TN was measured by comparing outcomes before and after the initiation of the TN. A total of 165,640 geriatric patients were evaluated. Multivariate regression methods were used to match and adjust for age, injury status (penetrating vs. nonpenetrating), sex, race, comorbidity, and injury severity (DRG International Classification of Diseases-9th Rev. Injury Severity Score). RESULTS: Since the advent of the TN, an additional 1,711 geriatric patients were treated compared with the previous period. The TN was responsible 86% of these new patients. There was a temporal association with a decrease in both mortality (adjusted odds ratio, 0.90; 95% confidence interval, 0.85-0.96) and length of stay (p < 0.0001) for geriatric patients since the advent of the TN. The improved access was associated with a significant decrease in mortality in the regions serviced by the TN. CONCLUSION: Geriatric patients make up a significant proportion of trauma patients within the TN. The temporal improvement in outcomes may be associated with the increased proportion of patients being treated in state-designated TCs as a result of the addition of the TN. LEVEL OF EVIDENCE: Epidemiologic study, level III.

Electron paramagnetic resonance analysis of a transient species formed during water oxidation catalyzed by the complex ion [(bpy)2Ru(OH2)]2O(4+).

The ruthenium "blue dimer" [(bpy)2Ru(OH2)]2O(4+)--the first well-defined molecular complex able to catalyze water oxidation at low overpotentials--has been the subject of numerous experimental and computational studies. However, elements of the reaction mechanism remain controversial. Of particular interest is the nature of the O-O bond-forming step. Herein, we report the first advanced electron paramagnetic resonance (EPR) spectroscopic studies of a high-valent intermediate that appears under conditions in which the catalyst is actively turning over. Results from previous studies have suggested that this intermediate is derived from [(bpy)2Ru(V)(O)]2O(4+), denoted {5,5}. Under photooxidizing conditions, the corresponding EPR signal disappears at a rate comparable to the turnover rate of the catalyst once the illumination source is removed. In the present work, the electronic and geometric structures of this species were explored using a variety of EPR techniques. Continuous wave (CW) EPR spectroscopy was used to probe the hyperfine coupling of the Ru ions, while corresponding ligand (14)N hyperfine couplings were characterized with electron spin echo envelope modulation (ESEEM) and hyperfine sublevel correlation spectroscopy (HYSCORE) methods. Finally, (1)H/(2)H ENDOR was performed to monitor any exchangeable protons. Our studies strongly suggest that the accumulating transient is an S = 1/2 species. This spin state formulation of the so-called {5,5} species is consistent with only a limited number of electronic structures, each of which is discussed. Notably, the observed large metal hyperfine coupling indicates that the orbital carrying the unpaired spin has significant ruthenyl-oxyl character, contrary to an earlier electronic structure description that had tentatively assigned the signal to formation of a bipyridine ligand radical.

Prospective evaluation of daily performance metrics to reduce emergency department length of stay for surgical consults.

BACKGROUND: As part of a quality improvement initiative to reduce Emergency Department (ED) length of stay (LOS) for surgical consult patients, we e-mailed performance metrics to key stakeholders on a daily basis. ED and Surgery leadership used these daily metrics to identify and remedy contributing factors for increased ED LOS in patients who received surgical consults. OBJECTIVE: To evaluate whether a quality improvement process driven by a daily performance metric e-mail would be associated with a change in ED LOS for surgical consult patients. METHODS: Prospective before-after study looking at ED LOS for surgical consult patients after an e-mail intervention at a tertiary academic teaching hospital. All consecutive adult ED patients between July 1, 2010 and October 1, 2010 who received a general surgical consult were enrolled. The primary outcome measure was ED LOS, and secondary outcome measure was time to consultation. RESULTS: There were 916 patients who had surgical consults placed during the study period; 459 patients presented before the intervention and 457 patients presented after the intervention. The median LOS decreased 54 min, from 463 min (interquartile range [IQR] 326-617) before the intervention to 409 min (IQR 294.5-528.5) after the intervention (p < 0.001). Time to consultation decreased 25 min, from a median of 160 min (IQR 87-265) to 135 min (IQR 70-239.5) (p = 0.002). There was no difference in age, severity, number of consults, or disposition. There was also no difference in median LOS for other consultation services or in previous years during the same time period. CONCLUSIONS: ED LOS and time to consultation were decreased for surgical consult patients after initiation of daily performance metric e-mails.

Anomalous reactivity of ceric nitrate in ruthenium "blue dimer"-catalyzed water oxidation.

At high concentrations, nitrate ion alters the dynamics of ruthenium "blue dimer"-catalyzed water oxidation by Ce(IV) such that the oxidation rate is enhanced and a unique reaction intermediate accumulates. This intermediate is characterized by distinct EPR, optical, and resonance Raman (RR) spectra, with the appearance in the latter of a new oxygen isotope-sensitive band. Both Ce(IV) and nitrate are required to generate this intermediate, which suggests ceric-nitrate complexes as the causative agents. Use of (18)O-labeled and (15)N-labeled materials has established that (1) the new RR band is not an O-O stretching mode (for example, as might be associated with a peroxo species) but involves the O atom coordinated to a Ru center, and (2) the O(2) product does not contain an O atom derived from nitrate, eliminating several plausible pathways involving O-atom transfer to oxidized dimer. Although these results are surprising, similar phenomena have been reported for water oxidation catalyzed by monomeric Ru complexes. The dramatic effects observed for the "blue dimer" make it an ideal candidate for further study.

Cyclic transmembrane charge transport mediated by low-potential pyrylium ions.

We have investigated the capacity of a series of N-dialkylaminophenyl-substituted pyrylium and thiopyrylium ions to act as photosensitizers and redox mediators between reactants separated by bilayer membranes. These studies were prompted by earlier results indicating that simple trimethy- and triphenyl-substituted analogues could promote efficient photosensitized transmembrane redox between vectorially organized reactants by an electroneutral e(-)/OH(-) antiport mechanism. Unlike the dyes used in the earlier studies, the ions investigated herein absorb strongly throughout the visible absorption region and are therefore potentially useful in solar photoconversion processes. We demonstrate that these ions can carry out cyclic electron transport between phase-separated electron donors and occluded Co(bpy)(3)(3+) in several transversely organized vesicles. The quantum yields obtained were relatively low, but were independent of the membrane microviscosity, suggesting that transmembrane diffusion was not rate-limiting. Triphenylpyrylium and triphenylthiopyrylium ions were shown to be capable of acting as combined photosensitizers/redox relays, apparently by direct oxidation of either solvent (water) or buffer (acetate) ions from their triplet-excited state. These reactions did not require addition of separate photosensitizers and electron donors; as such, they represent a minimal photochemical scheme for effecting transmembrane charge separation. The low-potential visible-absorbing pyrylium ions were unable to function in this dual capacity, consistent with thermodynamic limitations. However, redox titrations established that the pyranyl radicals of these dyes should be capable of reducing H(+) to H(2) in weakly acidic solutions. Consistent with their strongly reducing nature, these dyes were shown to be capable of forming methyl viologen radical in photoinitiated transmembrane redox reactions.

The determination of occupational exposure to polycyclic aromatic hydrocarbons by the analysis of 1-hydroxypyrene in urine using a simple automated online column switching device and high-performance liquid chromatography.

An analytical method using a liquid chromatograph combined with a simple online column switching sample pre-treatment system was developed for the determination of 1-hydroxypyrene (1-HP) in urine. This compound is the metabolite of pyrene and is used to assess the exposure of workers to polycyclic aromatic hydrocarbons (PAHs). After enzymatic hydrolysis, a urine sample was directly injected into a high-performance liquid chromatograph (HPLC) where it automatically underwent a sample cleanup using a column switching device. The procedure is simpler than previous methods because it uses only one switching valve, one extraction column and one HPLC pump. The analyte was retained on a short extraction column and after interferences were eluted to waste, was subsequently switched onto the analytical column. This allowed a short analysis time of 15 min. The calibration graph was found to be linear within the concentration range of 0.5 to 20 µg/L with a coefficient of determination exceeding r(2) = 0.99. Recoveries were found to be greater than 96% in the range 1 to 10 µg/L with intermediate precision of 2.5 to 5.8% relative standard deviation. This online method was verified by a comparison with an existing manual method by the analysis of 81 urine samples from workers exposed to PAHs and showed that the test results from both methods were in agreement with a probability obtained from the paired Student's t-test of P > 0.76. The proposed online method was found to be simple, fast and suited to routine analyses of 1-HP in urine for the assessment of occupational exposure to PAHs.

What really happens in the neutrophil phagosome?

Current viewpoints concerning the bactericidal mechanisms of neutrophils are reviewed from a perspective that emphasizes challenges presented by the inability to duplicate ex vivo the intracellular milieu. Among the challenges considered are the influences of confinement upon substrate availability and reaction dynamics, direct and indirect synergistic interactions between individual toxins, and bacterial responses to stressors. Approaches to gauging relative contributions of various oxidative and nonoxidative toxins within neutrophils using bacteria and bacterial mimics as intrinsic probes are also discussed.

Determination of quartz in bulk materials from workplace environments using X-ray diffractometry and the absorption diffraction method.

A method is described for the determination of crystalline quartz in bulk materials from workplace environments as part of occupational hygiene investigations using X-ray powder diffractometry. The absorption-diffraction model was used for quantification with mass absorption coefficients for samples being experimentally determined using an absorption cell placed in front of the diffracted beam anti-scatter slit. The method was found to be reliable for samples containing from 0.5 to 100 wt.% crystalline quartz, where mass absorption coefficients did not exceed 120 cm(2)g(-1). Repeatability studies found that mass absorption coefficient determinations and crystalline quartz determinations were both generally within 1-2% relative standard deviation. The method was assessed for accuracy and found to be within 2% absolute when a National Institute of Standards and Technology (NIST) quartz certified reference material (SRM1879a) was analysed. The technique was compared to an internal standard procedure and a paired students t test showed that there was no significant statistical difference between the two methods at the 95% confidence level where the t value was found to be 0.40 (p>0.05=0.69) and the t critical value being t(crit,0.05,29)=2.05. The method was suitable for a variety of matrixes including those containing amorphous material and could be routinely applied to most samples of occupational interest.

Perspectives on intraoperative teaching: divergence and convergence between learner and teacher.

OBJECTIVE: While current emphases on operative teaching focus on "virtual" education, residents and faculty engage most intimately in the operating room. The utilization of intraoperative teaching techniques, drawn from adult education principles, is understudied. DESIGN: A survey with both quantitative and qualitative elements was administered to surgical residents and their faculty. Thirty-eight analogous questions regarding teaching techniques, populating four general domains, were rated for frequency of application. Respondents were asked to rank best teaching practices and identify other effective educational approaches using open-ended questions. SETTING: University-based general surgical residency (5 institutions). PARTICIPANTS: General surgical residents and their faculty. RESULTS: 46 residents (77%) and 37 faculty (63%; mean 17 yrs experience) completed the survey. There was significant disagreement between residents and faculty in how frequently 32 of the 38 teaching techniques were applied (all p < 0.032). Faculty rated the technique "I set and communicate high standards" as the most frequently applied strategy, while residents rated "The faculty demonstrate technical consistency" the highest. The least employed approach, acknowledged by both groups, was "The faculty ask how they might improve their teaching." There were few differences between perceptions and preferences of junior vs. senior learners, and junior vs. senior faculty. Resident and faculty appreciation of most-effective teaching approaches was similar. Qualitative analysis of the open-ended questions yielded themes which resonate with both learners and teachers: communication processes, time pressures, optimization of the work/teaching environment, teacher engagement, patience/tolerance, autonomy, feedback, learner preparedness, and patient advocacy. CONCLUSIONS: The perceptions of residents and faculty regarding the frequency of using effective approaches for operative teaching are disparate. While faculty appear to value adult learning principles and perceive that they are employed regularly, residents have a discrepant viewpoint. However, themes that were identified by both residents and faculty through qualitative analysis provide the foundation for educational process improvements.

"Covalent hydration" reactions in model monomeric Ru 2,2'-bipyridine complexes: thermodynamic favorability as a function of metal oxidation and overall spin states.

Density functional theory (DFT) has been used to investigate the plausibility of water addition to the simple mononuclear ruthenium complexes, [(NH(3))(3)(bpy)Ru═O](2+/3+) and [(NH(3))(3)(bpy)RuOH](3+), in which the OH fragment adds to the 2,2'-bipyridine (bpy) ligand. Activation of bpy toward water addition has frequently been postulated within the literature, although there exists little definitive experimental evidence for this type of "covalent hydration". In this study, we examine the energetic dependence of the reaction upon metal oxidation state, overall spin state of the complex, as well as selectivity for various positions on the bipyridine ring. The thermodynamic favorability is found to be highly dependent upon all three parameters, with free energies of reaction that span favorable and unfavorable regimes. Aqueous addition to [(NH(3))(3)(bpy)Ru═O](3+) was found to be highly favorable for the S = 1/2 state, while reduction of the formal oxidation state on the metal center makes the reaction highly unfavorable. Examination of both facial and meridional isomers reveals that when bipyridine occupies the position trans to the ruthenyl oxo atom, reactivity toward OH addition decreases and the site preferences are altered. The electronic structure and spectroscopic signatures (EPR parameters and simulated spectra) have been determined to aid in recognition of "covalent hydration" in experimental systems. EPR parameters are found to uniquely characterize the position of the OH addition to the bpy as well as the overall spin state of the system.

Mathematical modeling to define optimum operating room staffing for pediatric patients in trauma centers.

BACKGROUND: Adult trauma centers (TCs) in the United States may be verified with an on-call operating room team if the performance improvement program shows no adverse outcome. Using queuing and simulation methodology, this study attempts to add a volume guideline for injured children. METHODS: Data from 63 verified TCs identified demographic factors including specific information regarding the first pediatric trauma-related operation done between 11 pm and 7 am each month for 1 year. RESULTS: The annual pediatric admits correlated with the number of operations (383) done from 11 pm to 7 am (P < .001). The probability of operation within 30 minutes of arrival varies with the number of admits and the percent of penetrating vs blunt injuries. This likely number of operations from 11 pm to 7 am beginning within 30 minutes of patient arrival would be 3.45, 4.21, and 4.95 for TCs admitting 150, 250, and 350 injured children per year, respectively. The probability that 2 rooms would be occupied simultaneously is 0.074 and 0.109 for centers with 160 and 260 pediatric trauma admissions, respectively. CONCLUSION: Trauma centers performing less than 6 pediatric trauma operations per year from 11 pm to 7 am could conserve resources by using an on-call operating room team.

Management of the most severely injured spleen: a multicenter study of the Research Consortium of New England Centers for Trauma (ReCONECT).

OBJECTIVE: To determine the rate and predictors of failure of nonoperative management (NOM) in grade IV and V blunt splenic injuries (BSI). DESIGN: Retrospective case series. SETTING: Fourteen trauma centers in New England. PATIENTS: A total of 388 adult patients with a grade IV or V BSI who were admitted between January 1, 2001, and August 31, 2008. MAIN OUTCOME MEASURES: Failure of NOM (f-NOM). RESULTS: A total of 164 patients (42%) were operated on immediately. Of the remaining 224 who were offered a trial of NOM, the treatment failed in 85 patients (38%). At the end, 64% of patients required surgery. Multivariate analysis identified 2 independent predictors of f-NOM: grade V BSI and the presence of a brain injury. The likelihood of f-NOM was 32% if no predictor was present, 56% if 1 was present, and 100% if both were present. The mortality of patients for whom NOM failed was almost 7-fold higher than those with successful NOM (4.7% vs 0.7%; P = .07). CONCLUSIONS: Nearly two-thirds of patients with grade IV or V BSI require surgery. A grade V BSI and brain injury predict failure of NOM. This data must be taken into account when generalizations are made about the overall high success rates of NOM, which do not represent severe BSI.