A Multicenter Evaluation of a Point-of-Care Blood Glucose Meter System in Critically Ill Patients.

BACKGROUND: Our purpose was to evaluate the performance of the ACCU-CHEK® Inform II blood glucose monitoring system (Roche Diagnostics GmbH) compared with the perchloric acid hexokinase (PCA-HK) comparator method on the cobas® 6000 analyzer (Roche Diagnostics International Ltd) in critically ill patients. METHODS: Overall, 476 arterial (376 pediatric/adult, 100 neonate), 375 venous, and 100 neonatal heel-stick whole-blood samples were collected and evaluated from critical care settings at 10 US hospitals, including the emergency department, medical and surgical intensive care units (ICUs), and neonatal and pediatric ICUs. The ACCU-CHEK Inform II system was evaluated at 2 cutoff boundaries: boundary 1 was ≥95% of results within ±12 mg/dL of the reference (samples with blood glucose <75 mg/dL) or ±12% of the reference (glucose ≥75 mg/dL), and boundary 2 was ≥98% of results within ±15 mg/dL or ±15% of the reference. Clinical performance was assessed by evaluating sample data using Parkes error grid, Monte Carlo simulation, and sensitivity and specificity analyses to estimate clinical accuracy and implications for insulin dosing when using the ACCU-CHEK Inform II system. RESULTS: Proportions of results within evaluation boundaries 1 and 2, respectively, were 96% and 98% for venous samples, 94% and 97% for pediatric and adult arterial samples, 84% and 98% for neonatal arterial samples, and 96% and 100% for neonatal heel-stick samples. Clinical evaluation demonstrated high specificity and sensitivity, with low risk of potential insulin-dosing errors. CONCLUSIONS: The ACCU-CHEK Inform II system demonstrated clinically acceptable performance against the PCA-HK reference method for blood glucose monitoring in a diverse population of critically ill patients in US care settings.

Large spin differences in structurally related Fe6 molecular clusters and their magnetostructural explanation.

The syntheses, crystal structures, and magnetic characterizations of three new hexanuclear iron(III) compounds are reported. Known [Fe(6)O(2)(OH)(2)(O(2)CBu(t))(10)(hep)(2)] (1) is converted to new [Fe(6)O(2)(OH)(O(2)CBu(t))(9)(hep)(4)] (3) when treated with an excess of 2-(2-hydroxyethyl)-pyridine (hepH). Similarly, the new compound [Fe(6)O(2)(OH)(2)(O(2)CPh)(10)(hep)(2)] (2), obtained from the reaction of [Fe(3)O(O(2)CPh)(6)(H(2)O)(3)] with hepH, is converted to [Fe(6)O(2)(OH)(O(2)CPh)(9)(hep)(4)] (4) when treated with an excess of hepH. This can be reversed by recrystallization from MeCN. The cores of the four Fe(6) complexes all comprise two triangular [Fe(3)(mu(3)-O)(O(2)CR)(3)(hep)](+3) units connected at two of their apices by two sets of bridging ligands. However, 1 and 2 differ slightly from 3 and 4 in the precise way the two Fe(3) units are linked together. In 1 and 2, the two sets of bridging ligands are identical, consisting of one mu-hydroxo and two mu-carboxylate groups bridging each Fe(2) pair, i.e., a (mu-OH(-))(mu-O(2)CR(-))(2) set. In contrast, 3 and 4 have two different sets of bridging ligands, a (mu-OH(-))(mu-O(2)CR(-))(2) set as in 1 and 2, and a (mu-OR(-))(2)(mu-O(2)CR(-)) set, where RO(-) refers to the alkoxide arm of the hep(-) chelate. Variable-field and -temperature dc magnetization measurements establish that 1 and 2 have S = 5 ground states and significant and positive zero-field splitting parameters (D), whereas 3 and 4 have S = 0 ground states. This dramatic difference of 10 unpaired electrons in the ground state S values for near-isomeric compounds demonstrates an acute sensitivity of the magnetic properties to small structural changes. The factors leading to this have been quantitatively analyzed. The semiempirical method ZILSH, based on unrestricted molecular orbital calculations, was used to obtain initial estimates of the Fe(2) pairwise exchange interaction constants (J). These calculated values were then improved by fitting the experimental susceptibility versus T data, using a genetic algorithm approach. The final J values were then employed to rationalize the observed magnetic properties as a function of the core topologies and the presence of spin frustration effects. The large difference in ground state spin value was identified as resulting from a single structural difference between the two types of complexes, the different relative dispositions (cis vs trans) of two frustrated exchange pathways. In addition, use of the structural information and corresponding J values allowed a magnetostructural correlation to be established between the J values and both the Fe-O bond distances and the Fe-O-Fe angles at the bridging ligands.

Polynuclear manganese complexes with the dicarboxylate ligand m-phenylenedipropionate: a hexanuclear mixed-valence (3Mn(III), 3Mn(IV)) complex.

The dicarboxylate group m-phenylenedipropionate (mpdp(2)(-)) has been used for the synthesis of four new Mn compounds of different nuclearities and oxidation states: [Mn(2)O(mpdp)(bpy)(2)(H(2)O)(MeCN)](ClO(4))(2) (3), [Mn(3)O(mpdp)(3)(py)(3)](ClO(4)) (4), [Mn(3)O(mpdp)(3)(py)(3)] (5), and [Mn(6)O(7)(mpdp)(3)(bpy)(3)](ClO(4)) (6). Compound 3 (2Mn(III)) contains a [Mn(2)(micro-O)](4+) core, whereas 5 (Mn(II), 2Mn(III)) and 4 (3Mn(III)) contain the [Mn(3)(micro(3)-O)](6+,7+) core, respectively. In all three compounds, the mpdp(2)(-) ligand is flexible enough to adopt the sites occupied by two monocarboxylates in structurally related compounds, without noticeable distortion of the cores. Variable-temperature magnetic susceptibility studies establish that 3 and 5 have ground-state spin values of S = 0 and S = 1/2, respectively. Compound 6 is a highly unusual 3Mn(III), 3Mn(IV) trapped-valent compound, and it is also a new structural type, with six Mn atoms disposed in a distorted trigonal antiprismatic topology. Its electronic structure has been explored by variable-temperature measurements of its dc magnetic susceptibility, magnetization vs field response, and EPR spectrum. The magnetic data indicate that it possesses an S = 3/2 ground state with an axial zero-field splitting parameter of D = -0.79 cm(-)(1), and this conclusion is supported by the EPR data. The combined results demonstrate the ligating flexibility of the mpdp(2)(-) ligand and its usefulness in the synthesis of a variety of Mn(x) species.

Methanolysis and phenolysis routes to Fe6, Fe8, and Fe1) complexes and their magnetic properties: a new type of Fe8 ferric wheel.

Alcoholysis of preformed tetranuclear and hexanuclear iron(III) clusters has been employed for the synthesis of four higher-nuclearity clusters. Treatment of [Fe(4)O(2)(O(2)CMe)(7)(bpy)(2)](ClO(4)) with phenol affords the hexanuclear cluster [Fe(6)O(3)(O(2)CMe)(9)(OPh)(2)(bpy)(2)](ClO(4)) (1). Reaction of [Fe(6)O(2)(OH)(2)(O(2)CR)(10)(hep)(2)] (R = Bu(t) or Ph) with PhOH affords the new "ferric wheel" complexes [Fe(8)(OH)(4)(OPh)(8)(O(2)CR)(12)] [R = Bu(t) (2) or Ph (3)]. Complexes 2 and 3 exhibit the same structure, which is an unprecedented type for Fe(III). In contrast, treatment of [Fe(6)O(2)(OH)(2)(O(2)CBu(t))(10)(hep)(2)] with MeOH leads to the formation of [Fe(10)(OMe)(20)(O(2)CBu(t))(10)] (4), which exhibits the more common type of ferric wheel seen in analogous complexes with other carboxylate groups. Solid-state variable-temperature magnetic susceptibility measurements indicate spin-singlet ground states for complexes 2 and 4. The recently developed semiempirical method ZILSH was used to estimate the pairwise exchange parameters (J(AB)) and the average spin couplings S(A)[empty set].S(B)[empty set] between the Fe(III) centers, providing a clear depiction of the overall magnetic behavior of the molecules. All exchange interactions between adjacent Fe(III) atoms are antiferromagnetic.

A phenolysis route to a new type of octanuclear iron(III) wheel: [Fe8(OH)4(OPh)8(O2CBut)12].

Alcoholysis of [Fe6O2(OH)2(O2CBut)10(hep)2] (1) affords ferric wheels of different nuclearities: methanol yields [Fe10(OMe)20(O2CBut)10], whereas phenol gives the structurally unprecedented wheel [Fe8(OH)4(OPh)8(O2CBut)12], and the first to contain phenoxide.