Structure of N,4-dinitroaniline and its complex with sulfolane at 85 K; on the proton donor-acceptor affinity of the primary nitramine (HNNO2) group.

The NNO2 group of the title compound is significantly less twisted with respect to the aromatic ring in comparison to a typical secondary nitramine. The amide nitrogen is trigonally hybridized. The nitramino group is almost planar. The C-C-N-N torsion angles vary between ca 13 and 42 degrees, whereas the twist along the N-N bond is much smaller and amounts to between ca 1 and 15 degrees. Those twist angles are governed by a crystal packing and are much larger in the case of crystals of pure N,4-dinitroaniline in comparison to that of its complex with sulfolane. The deviations of the internal angles of the aromatic ring from 120 degrees do not exceed 3 degrees. The presence of the nitro group increases the C-C-C valence angle of ca 2.0-2.6 degrees, whereas an analogous effect associated with the nitramino group is much smaller (ca 0.3-1.3 degrees), pointing to its weak electron-withdrawing properties. The nitramino group displays no tendency to conjugate with an electron-demanding substituent across the ring. It participates in hydrogen bonding only as a hydrogen-bonding donor. It does not act as a proton acceptor, despite the fact that nitramine rearrangement is catalysed by acids.

Macrocyclic metalloenediynes of Cu(II) and Zn(II): a thermal reactivity comparison.

The syntheses of tetradentate enediyne macrocycles with 24 (tact1:1)-, 26 (tact1:2)-, and 28 (tact2:2)-membered rings are described, along with their thermal reactivities and those of the corresponding Cu(II) (Cu(tact1:1), Cu(tact1:2)) and Zn(II) (Zn(tact1:1), Zn(tact1:2)) complexes. These enediyne macrocyclic ligands are not benzannulated and thus exhibit thermal Bergman cyclization temperatures near 200 degrees C by differential scanning calorimetry (DSC). Moreover, the synthetic route allows incorporation of additional carbon atoms into the macrocycles which increases their conformational flexibilities and lowers their Bergman cyclization temperatures. Specifically, as the size of the macrocycle increases, the temperatures at which these compounds undergo Bergman cyclization decrease by approximately 5 degrees C per additional carbon atom, leading to an overall decrease across the series of 19 degrees C. Incorporation of Cu(II) and Zn(II) into these macrocycles further reduces their cyclization temperatures relative to those of the free ligands. More uniquely, for Cu(tact1:1) and Zn(tact1:1), the observed cyclization temperatures vary by 27 degrees C with the Zn(II) complex lying to higher temperature (Cu(tact1:1) = 121 degrees C, (Zn(tact1:1) = 148 degrees C). As the macrocycle size is increased, the decrease in the Bergman cyclization temperatures observed for the free ligands does not systematically hold for the Cu(II) and Zn(II) derivatives. Rather, the Cu(II) complex exhibits the expected 9 degrees C decrease in the cyclization temperature (Cu(tact1:2) = 112 degrees C), whereas the temperature for the Zn(II) analogue increases by 15 degrees C (Zn(tact1:2) = 163 degrees C). From the X-ray crystal structure of the free ligand and the geometric structural preferences of the electronic configurations of Cu(II) and Zn(II), the higher cyclization temperatures for the Zn(II) complex with the larger ring size can be explained by a distortion of the macrocycle toward a more tetrahedral metal center geometry.

Support of clinician image-related workflow by a user-edited, web-based patient list manager.

Clinician efficiency can be enhanced by worklists that compile useful data for rapid access at the time of need. The authors report development of a web-based, user-edited "Patient List Manager" for the Clinical Image Management System (CIMS). The CIMS List Manager interfaces with the CIMS Archive to provide the user with available studies. It has tools that let the user build personal lists from the available studies. Listed studies are moved from the archive to the cache for rapid access at the time of need. Users can build/edit the list through a browser (without viewing pictures) or from within the image viewer. In this way, the List Manager distributes list building into knowledgeable hands. This is particularly valuable at the current time when health system patient registries are not mature enough to reliably support building build anticipatory patient lists.

The Digital Imaging and Communications in Medicine (DICOM) archive is a dynamic component of a clinician image-related workflow solution.

The authors investigated clinician transactions against the Digital Imaging and Communications in Medicine (DICOM) archive within a clinical image management system (CIMS) in support of patient care. A Neurosurgical Oncology practice was audited for image utilization. There were 400 requests for 233 image studies during 297 sessions. Fifty percent were for current studies, and 50% were for historical studies. Current studies alone were requested in 37% of the sessions, current plus historical in 31%, and historical alone in 32% of the sessions. Seventy percent of studies were within 8 weeks old and were rapidly available from the CIMS disk cache without an archive image transaction. Conversely, 30% were older than 8 weeks, requiring a clinician transaction against the archive for image retrieval. Approximately 25% of studies were older than 3 months and 10% older than 6 months. Clinician image needs are complex and any CIMS solution must include a DICOM archive that can support clinician-based transactions.

UDFT and MCSCF descriptions of the photochemical Bergman cyclization of enediynes.

Several singlet and triplet potential energy surfaces (PES) for the Bergman cyclization of cis-1,5-hexadiyne-3-ene (1a) have been computed by UDFT, CI, CASCI, CASSCF, and CASMP2 methods. It is found that the first six excited states of 1a can be qualitatively described as linear combinations of the configurations of weakly interacting ethylene and acetylene units. Although the symmetry relaxation from C2nu to C2 makes cyclization of the 13B state Woodward-Hoffmann allowed, it also increases the probability of competing cis-trans isomerization. Hydrogen atom abstraction is another plausible pathway because the terminal alkyne carbons possess a large radical character. In view of the competing processes, we conclude that the Bergman cyclization along the 13B path is unlikely despite its exothermicity (Delta = -42 kcal/mol). Calculations on cyclic analogues of 1a lead to similar conclusions. A less exothermic, but more plausible pathway for photochemical cyclization lies on the 2(1)A PES (Delta = -18 kcal/mol). Compared to the 1(1)A(1) and 1(3)B states, the 2(1)A state has less in-plane electron repulsion which may facilitate cyclization. The resulting p-benzyne intermediate has an unusual electronic structure combining singlet carbene and open-shell diradical features. Deactivation of the 2(1)A state of 1a is a competing pathway.

1-methyl-4-nitraminopyridinium nitrate and 4-nitraminopyridinium methanesulfonate.

In the title compounds, C6H8N3O2+*NO3- and C5H6N3O2+*-CH3SO3-, respectively, the cations are almost planar; the twist of the nitramino group about the C-N and N-N bonds does not exceed 10 degrees. The deviations from coplanarity are accounted for by intermolecular N-H...O interactions. The coplanarity of the NHNO2 group and the phenyl ring leads to the deformation of the nitramino group. The C-N-N angle and one C-C-N angle at the junction of the phenyl ring and the nitramino group are increased from 120 degrees by ca 6 degrees, whereas the other junction C-C-N angle is decreased by ca 5 degrees. Within the nitro group, the O-N-O angle is increased by ca 5 degrees and one O-N-N angle is decreased by ca 5 degrees, whereas the other O-N-N angle remains almost unchanged. The cations are connected to the anions by relatively strong N-H...O hydrogen bonds [shortest H.O separations 1.77 (2)-1.81 (3) A] and much weaker C-H...O hydrogen bonds [H...O separations 2.30 (2)-2.63 (3) A].

The contribution of ligand flexibility to metal center geometry modulated thermal cyclization of conjugated pyridine and quinoline metalloenediynes of copper(I) and copper(II).

We report the syntheses, reactivities, and structure evaluations of a series of Cu(I) and Cu(II) metalloenediynes of conjugated 1,6-bis(pyridine-3)hex-3-ene-1,5-diyne (PyED, 7) and 1,6-bis(quinoline-3)hex-3-ene-1,5-diyne (QnED, 8) enediyne ligands, as well as their benzoenediyne analogues. Differential scanning calorimetry demonstrates that the [Cu(PyED)(2)](NO(3))(2) (11) exhibits a Bergman cyclization temperature (156 degrees C) which is dramatically reduced from that of the corresponding [Cu(PyED)(2)](PF(6)) (19) analogue (326 degrees C), indicating that large differences in the reactivities of these metalloenediynes can be accessed by variations in metal oxidation state. The distorted, 4-coordinate dichloride compound Cu(PyED)(Cl)(2) (15) exhibits a cyclization temperature (265 degrees C) between those of 11 and 19, suggesting that variation in geometry of the copper center is responsible for the wide range of reactivities. Similar results are obtained for the benzoenediyne and quinoline analogues. The structures of the Cu(II) systems have also been evaluated by a combination of electronic absorption and EPR spectroscopies which reveal tetragonal, 6-coordinate structures for the bis(enediyne) complexes, and tetrahedrally distorted 4-coordinate Cu(enediyne)Cl(2) species. For the bis(quinoline) enediyne derivatives 12 and 14 the larger g-anisotropy (g( parallel) = 2.27-2.28; g( perpendicular) = 2.06-2.07) indicates strong oxygen coordination from counterion. Molecular mechanics/dynamics calculations reveal that the geometries of these metal centers force the alkyne termini to a wide range of distances (3.85-4.20 A), thereby accounting for the variability in Bergman cyclization temperatures. Overall, the results show that ligand rigidity plays a prominent role in the conformational response of the enediyne to metal center geometry, which results in enhanced variations in the Bergman cyclization temperatures between complexes of different geometries.

Aminoguanidinium(2+) aminoguanidinium(1+) hexachloroantimonate(III) at 295 and 92 K.

The crystal and molecular structure of the title compound, (CH(7)N(4))(CH(8)N(4))[SbCl(6)], has been determined at 295 and 92 K. It is composed of isolated [SbCl(6)](3-) octahedra and aminoguanidinium mono- and dications. One of four of the crystallographically inequivalent aminoguanidinium cations is disordered at both temperatures. Two crystallographically inequivalent [SbCl(6)](3-) octahedra were found to possess three significantly longer Sb-Cl bonds than three other octahedra. The shorter bonds are in the range 2.456 (2)-2.577 (2) A, whereas the longer ones are between 2.705 (2) and 2.931 (2) A. Each short Sb-Cl bond is located trans to a long bond. It is argued that this deformation is caused by N-H.Cl hydrogen bonds.

Two trans-4-aminoazoxybenzenes.

Two isomeric trans-4-aminoazoxybenzenes, trans-1-(4-aminophenyl)-2-phenyldiazene 2-oxide (alpha, C(12)H(11)N(3)O) and trans-2-(4-aminophenyl)-1-phenyldiazene 2-oxide (beta, C(12)H(11)N(3)O), have been characterized by X-ray diffraction. The alpha isomer is almost planar, having torsion angles along the C(aryl)-N bonds of only 4.9 (2) and 8.0 (2) degrees. The relatively short C(aryl)-N bond to the non-oxidized site of the azoxy group [1.401 (2) A], together with the significant quinoid deformation of the respective phenyl ring, is evidence of conjugation between the aromatic sextet and the pi-electron system of the azoxy group. The geometry of the beta isomer is different. The non-substituted phenyl ring is twisted with respect to the NNO plane by ca 50 degrees, whereas the substituted ring is almost coplanar with the NNO plane. The non-oxidized N atom in the beta isomer has increased sp(3) character, which leads to a decrease in the N-N-C bond angle to 116.8 (2) degrees, in contrast with 120.9 (1) degrees for the alpha isomer. The deformation of the C-C-C angles (1-2 degrees ) in the phenyl rings at the substitution positions is evidence of the different character of the oxidized and non-oxidized N atoms of the azoxy group. In the crystal structures, molecules of both isomers are arranged in chains connected by weak N-H.O (alpha and beta) and N-H.N (beta) hydrogen bonds.

1-Nitroindoline.

In the title compound, C(8)H(8)N(2)O(2), the nitramino group is planar and only slightly twisted with respect to the indoline rings. The bridgehead N--C bond is slightly shorter than in typical secondary aromatic nitramines. The N--N bond has some double-bond character. The molecules are connected by weak C--H...O hydrogen bonds, forming chains parallel to the z direction.

2,3-Dihydro-3-methyl-2-nitrimino-1,3-thiazole.

The title compound ¿alternatively, 3-methyl-2-[oxido(oxo)hydrazono]-2,3-dihydro-1,3-thiazole¿, C(4)H(5)N(3)O(2)S, was obtained by methylation of N-(2-thiazolyl)nitramine. The molecule lies on a mirror plane and the thiazole ring is planar, regular in shape and aromatic. The S atom participates in the aromatic sextet via an electron pair on the 3p(z) orbital. In the crystal, the molecules are arranged in parallel layers, bound to each other by weak C-H.O and C-H.N hydrogen bonds and by S.O dipolar interactions, with an interlayer separation of 3.23 A.

Characterization of the Ni(III) intermediate in the reaction of (1,4,8,11-tetraazacyclotetradecane)nickel(II) perchlorate with KHSO5: implications to the mechanism of oxidative DNA modification.

We report the detection and characterization of the Ni(III) intermediates generated by reaction of (1,4,8,11-tetraazacyclotetradecane)nickel(II) perchlorate with KHSO5. Four Ni(III) intermediates can be trapped or detected through variation in Cl- or KHSO5 concentrations. Upon oxidation of [Ni(cyclam)]2+ by 2.5 equiv of KHSO5, deprotonation of the cyclam ligand generates two red Ni(III) species with lambda max = 530 nm and g perpendicular = 2.20 and g parallel = 2.02 or g perpendicular = 2.16 and g parallel = 2.01 for the axial 4-coordinate or 6-coordinate dichloride species, respectively. These forms decay to Ni(II) products via complex ligand oxidation mechanisms. The Ni(III) dichloride species can be reprotonated and subsequently binds to DNA via an outer-sphere interaction as evidenced by the inverted sign of the CD signal near 400 nm. Cumulatively, the results indicate that the Ni(III) center is coordinately saturated under excess chloride conditions but is still able to interact with DNA substrates. This suggests alternative mechanistic pathways for DNA modification by reaction of [Ni(cyclam)]2+ with KHSO5 and possibly other Ni(II) complexes as well.

Modeling spontaneous minute volume in coronary artery bypass graft patients.

This article presented a mathematical method by which the future trajectory of patient SMV may be predicted in the postoperative weaning period. The method outlined enables critical-care staff to predict the SMV trajectory up to 30 minutes into the future. Having this capability enables physicians, respiratory therapists, and nurses to more efficiently guide patient treatment and schedule rounds within the ICU.

Variables and designs in psychiatric/mental health nursing research articles published from 1982 to 1992.

Research designs and variables of interest were classified in 194 mental health psychiatric articles published between 1982 and 1992. Common variables only could be identified in 100 articles and independent and dependent variables were identified in the remaining 94 articles. The majority of research designs were descriptive. The variables pertained to diverse interests from nurse and patient perspectives, specifically including patients' behavioural responses to illness, care and caregivers. These variables were then compared by the writers to the current research foci as identified in the recent literature. As listed, these are: biological psychiatry; working with the chronically and persistently mentally ill; shifting of care to the community; working with consumers; and outcome research. There is some link between research published between 1982 and 1992 and current trends in design and a few variables of interest. However, current researchers in mental health psychiatric nursing need to change foci and their relationships with other disciplines to ensure relevancy in their research programmes.

A systematic review of the psychiatric/mental health nursing research literature 1982-1992.

The purpose of this study was to assess the quality of quantitative psychiatric/mental health nursing research articles published in English between 1982 and 1992, worldwide. Criteria for selection of articles included nurse authorship or co-authorship, use of a quantitative design and pertinence to an aspect of the nursing process with psychiatric/mental health patients. One hundred and ninety-four articles met these criteria. The quality of each article was assessed by two nurse experts using Duffy's Research Appraisal Checklist (RAC). Forty-six point nine per cent of the articles were rated as superior, 50% as average and 3.1% as below average. Other findings identified journals that published research articles, countries in which research was completed, applicability of funding and qualifications of the authors. The major implications of this study are that nurses can be directed to superior articles; more publication of research by nurse authors is warranted, research is being completed with little financial support, highly rated research publications tend to get funding and editorial policies affect the quality of publication.

Toxicity of allyl alcohol in primary cultures of freshly isolated and cryopreserved hepatocytes maintained on hydrated collagen gels.

The toxicity of allyl alcohol was compared in freshly isolated and cryopreserved hepatocytes that were either placed in suspension or maintained on hydrated collagen gels in a sandwich configuration. The purpose of this study was to evaluate whether the two types of cells displayed the same sensitivity to allyl alcohol when maintained in vitro over relatively prolonged periods of time. The important differentiated functions of urea synthesis, secretion of albumin, and metabolism of ethoxycoumarin, a model drug substrate, were used as end points of toxicity. Cryopreserved hepatocytes incubated in physiological buffer shortly after removal from liquid nitrogen were more sensitive to allyl alcohol than freshly isolated hepatocytes. In contrast, cryopreserved and freshly isolated hepatocytes maintained on hydrated collagen gels responded identically to allyl alcohol. Thus, the increased sensitivity of cryopreserved hepatocytes in suspension to allyl alcohol is a transient phenomenon that disappears after the cells have been allowed to recover on hydrated collagen gels. Dissipation of the mitochondrial membrane potential by allyl alcohol, as indexed by rhodamine 123 fluorescence, was also the same in freshly isolated and cryopreserved hepatocytes maintained on hydrated collagen matrices. This loss of mitochondrial membrane potential caused by allyl alcohol preceded inhibition of albumin and urea biosynthesis. Collectively, the results indicate that cryopreserved cells maintained on hydrated collagen gels provide a useful system to define the actions of certain hepatotoxic agents over relatively prolonged periods of time in vitro.

Actions of selected hepatotoxicants on freshly isolated and cryopreserved rat hepatocytes.

The present study compares the actions of the hepatotoxic agents allyl alcohol, acetaminophen, and carbon tetrachloride on energy metabolism in freshly isolated and cryopreserved rat hepatocytes. After 30 min incubation of freshly isolated hepatocytes at 37 degrees C to allow metabolic equilibration, hepatocytes were supplemented with cryoprotectants and cooled in a stepwise manner to liquid nitrogen temperature. Hepatocytes stored in liquid nitrogen for 2 weeks to 6 months were thawed and centrifuged through Percoll to remove damaged cells. Despite similarities in energy status as indexed by ATP content and the rate of urea synthesis in freshly isolated and cryopreserved hepatocytes, cryopreserved hepatocytes were more sensitive to hepatotoxicants. All three hepatotoxicants caused ATP and rates of urea synthesis to decline to a greater extent in cryopreserved than in freshly isolated hepatocytes. Rates of oxygen uptake were higher in cryopreserved cells than in freshly isolated hepatocytes and declined in cryopreserved cells but not in freshly isolated cells during the initial period of incubation. Rates of mitochondrial respiration stimulated with site-specific substrates were comparable in freshly isolated and cryopreserved cells permeabilized with digitonin. Allyl alcohol and acetaminophen inhibited site-specific respiration to the same extent in both groups of cells. Collectively, these results suggest that increased sensitivity to hepatotoxic agents and elevated oxygen consumption in cryopreserved hepatocytes recovered after storage in liquid nitrogen are related to higher demand for energy in these cells rather than to permanent injury caused by cryopreservation and irreversible uncoupling of oxidative phosphorylation.