Gas phase ion chemistry of titanium-oxofullerene with ligated solvents

We investigated the gas phase fragmentation events of highly symmetric fullerene-like (FN-like) titanium oxo-cluster anions, [H₁₂Ti₄₂O₆₀(OCH₃)₄₂(HOCH₃)₁₀(H₂O)₂]^2- (1) and [H₇Ti₄₂O₆₀(OCH₃)₄₂(HOCH₃)₁₀(H₂O)₃]^1- (2). These oxo-clusters contain a closed cage Ti₄₂O₆₀ core, protected by a specific number of methoxy, methanol, and water molecules acting as ligands. These dianionic and monoanionic species were generated in the gas phase by electrospray ionization of the H₆[Ti₄₂(μ³-O)₆₀(OⁱPr)₄₂(OH)₁₂] (TOF) cluster in methanol. Collision induced dissociation studies of 1 revealed that upon increasing the collision energy, the protecting ligands were stripped off first, and [Ti₄₁O₅₈]^2- was formed as the first fragment from the Ti₄₂O₆₀ core. Thereafter, systematic TiO₂ losses were observed giving rise to subsequent fragments like [Ti₄₀O₅₆]^2-, [Ti₃₉O₅₄]^2-, [Ti₃₈O₅₂]^2-, etc. Similar fragments were also observed for monoanionic species 2 as well. Systematic 23 TiO₂ losses were observed, which were followed by complete shattering of the cage. We also carried out computational studies using density functional theory (DFT) to investigate the structures and fragmentation mechanism. The fragmentation of TOF was comparable to the fragmentation of C₆₀ ions, where systematic C₂ losses were observed. We believe that this is a consequence of topological similarity. The present study provides valuable insights into the structural constitution of TOF clusters and stability of the parent as well as the resulting cage-fragments in the gas phase.

Metal-Ligand Interface in the Chemical Reactions of Ligand-Protected Noble Metal Clusters

We discuss the role of the metal-ligand (M-L) interfaces in the chemistry of ligand-protected, atomically precise noble metal clusters, a new and expanding family of nanosystems, in solution as well as in the gas phase. A few possible mechanisms by which the structure and dynamics of M-L interfaces could trigger intercluster exchange reactions are presented first. How interparticle chemistry can be a potential mechanism of Ostwald ripening, a well-known particle coarsening process, is also discussed. The reaction of Ag₅₉(2,5-DCBT)₃₂ (DCBT = dichlorobenzenethiol) with 2,4-DCBT leading to the formation of Ag₄₄(2,4-DCBT)₃₀ is presented, demonstrating the influence of the ligand structure in ligand-induced chemical transformations of clusters. We also discuss the structural isomerism of clusters such as Ag₄₄(SR)₃₀ (-SR = alkyl/aryl thiolate) in the gas phase wherein the occurrence of isomerism is attributed to the structural rearrangements in the M-L bonding network. Interfacial bonding between Au₂₅(SR)₁₈ clusters leading to the formation of cluster dimers and trimers is also discussed. Finally, we show that the desorption of phosphine and hydride ligands on a silver cluster, [Ag₁₈(TPP)₁₀H₁₆]²⁺ (TPP = triphenylphosphine) in the gas phase, leads to the formation of a naked silver cluster of precise nuclearity, such as Ag₁₇⁺. We demonstrate that the nature of the M-L interfaces, i.e., the oxidation state of metal atoms, structure of the ligand, M-L bonding network, and so forth, plays a key role in the chemical reactivity of clusters. The structure, dynamics, and chemical reactivity of nanosystems in general are to be explored together to obtain new insights into their emerging science.

A covalently linked dimer of [Ag25(DMBT)18]−

We report the first example of a covalently bound dimer of monolayer protected atomically precise silver nanocluster [Ag₂₅(DMBT)₁₈]⁻ (DMBT stands for 2,4-dimethylbenzenethiol).

Rapid isotopic exchange in nanoparticles

Rapid solution-state exchange dynamics in nanoscale pieces of matter is revealed, taking isotopically pure atomically precise clusters as examples. As two isotopically pure silver clusters made of ¹⁰⁷Ag and ¹⁰⁹Ag are mixed, an isotopically mixed cluster of the same entity results, similar to the formation of HDO, from H₂O and D₂O. This spontaneous process is driven by the entropy of mixing and involves events at multiple time scales.

Bent Keto Form of Curcumin, Preferential Stabilization of Enol by Piperine, and Isomers of Curcumin∩Cyclodextrin Complexes: Insights from Ion Mobility Mass Spectrometry

A detailed examination of collision cross sections (CCSs) coupled with computational methods has revealed new insights into some of the key questions centered around curcumin, one of the most intensively studied natural therapeutic agents. In this study, we have distinguished the structures and conformers of the well-known enol and the far more elusive keto form of curcumin by using ion mobility mass spectrometry (IM MS). The values of the theoretically predicted isomers were compared with the experimental CCS values to confirm their structures. We have identified a bent structure for the keto form and the degree of bending was estimated. Using IM MS, we have also shown that ESI MS reflects the solution phase structures and their relative populations, in this case. Piperine, a naturally occurring heterocyclic compound, is known to increase the bioavailability of curcumin. However, it is still not clearly understood which tautomeric form of curcumin is better stabilized by it. We have identified preferential stabilization of the enol form in the presence of piperine using IM MS. Cyclodextrins (CDs) are used as well-known carriers in the pharmaceutical industry for increasing the stability, solubility, bioavailability, and tolerability of curcumin. However, the crystal structures of supramolecular complexes of curcumin∩CD are unknown. We have determined the structures of different isomers of curcumin∩CD (α- and β-CD) complexes by comparing the CCSs of theoretically predicted structures with the experimentally obtained CCSs, which will further help in understanding the specific role of the structures involved in different biological activities.

Atomically Precise Nanocluster Assemblies Encapsulating Plasmonic Gold Nanorods

The self-assembled structures of atomically precise, ligand-protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs) is presented. Unlike highly sophisticated DNA nanotechnology, this strategically simple hydrogen bonding-directed self-assembly of nanoclusters leads to octahedral nanocrystals encapsulating GNRs. Specifically, the p-mercaptobenzoic acid (pMBA)-protected atomically precise silver nanocluster, Na₄ [Ag₄₄ (pMBA)₃₀ ], and pMBA-functionalized GNRs were used. High-resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H-bonding, leading to octahedral symmetry. The use of water-dispersible gold nanoclusters, Au_≈250 (pMBA)_n and Au₁₀₂ (pMBA)₄₄ , also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles are a new category of precision hybrids with diverse possibilities.

Fullerene-Functionalized Monolayer-Protected Silver Clusters: [Ag29(BDT)12(C60) n]3- ( n = 1-9)

We report the formation of supramolecular adducts between monolayer-protected noble metal nanoclusters and fullerenes, specifically focusing on a well-known silver cluster, [Ag₂₉(BDT)₁₂]^3-, where BDT is 1,3-benzenedithiol. We demonstrate that C₆₀ molecules link with the cluster at specific locations and protect the fragile cluster core, enhancing the stability of the cluster. A combination of studies including UV-vis, high-resolution electrospray ionization mass spectrometry, collision-induced dissociation, and nuclear magnetic resonance spectroscopy revealed structural details of the fullerene-functionalized clusters, [Ag₂₉(BDT)₁₂(C₆₀) _n]^3- ( n = 1-9). Density functional theory (DFT) calculations and molecular docking simulations affirm compatibility between the cluster and C₆₀, resulting in its attachment at specific positions on the surface of the cluster, stabilized mainly by π-π and van der Waals interactions. The structures have also been confirmed from ion mobility mass spectrometry by comparing the experimental collision cross sections (CCSs) with the theoretical CCSs of the DFT-optimized structures. The gradual evolution of the structures with an increase in the number of fullerene attachments to the cluster has been investigated. Whereas the structure for n = 4 is tetrahedral, that of n = 8 is a distorted cube with a cluster at the center and fullerenes at the vertices. Another fullerene, C₇₀, also exhibited similar behavior. Modified clusters are expected to show interesting properties.

An Integration of Health Tracking Sensor Applications and eLearning Environments for Cloud-Based Health Promotion Campaigns

Rapidly evolving technologies like data analysis, smartphone and web-based applications, and the Internet of things have been increasingly used for healthy living, fitness and well-being. These technologies are being utilized by various research studies to reduce obesity. This paper demonstrates design and development of a dataflow protocol that integrates several applications. After registration of a user, activity, nutrition and other lifestyle data from participants are retrieved in a centralized cloud dedicated for health promotion. In addition, users are provided accounts in an e-Learning environment from which learning outcomes can be retrieved. Using the proposed system, health promotion campaigners have the ability to provide feedback to the participants using a dedicated messaging system. Participants authorize the system to use their activity data for the program participation. The implemented system and servicing protocol minimize personnel overhead of large-scale health promotion campaigns and are scalable to assist automated interventions, from automated data retrieval to automated messaging feedback. This paper describes end-to -end workflow of the proposed system. The case study tests are carried with Fitbit Flex2 activity trackers, Withings Scale, Verizon Android-based tablets, Moodle learning management system, and Articulate RISE for learning content development.

A targeted noise reduction observational study for reducing noise in a neonatal intensive unit

BACKGROUND

Excessive noise in neonatal intensive care units (NICUs) can interfere with infants' growth, development and healing.Local problem:Sound levels in our NICUs exceeded the recommended levels by the World Health Organization.

METHODS

We implemented a noise reduction strategy in an urban, tertiary academic medical center NICU that included baseline noise measurements. We conducted a survey involving staff and visitors regarding their opinions and perceptions of noise levels in the NICU. Ongoing feedback to staff after each measurement cycle was provided to improve awareness, engagement and adherence with noise reduction strategies. After widespread discussion with active clinician involvement, consensus building and iterative testing, changes were implemented including: lowering of equipment alarm sounds, designated 'quiet times' and implementing a customized education program for staff.

INTERVENTIONS

A multiphase noise reduction quality improvement (QI) intervention to reduce ambient sound levels in a patient care room in our NICUs by 3 dB (20%) over 18 months.

RESULTS

The noise in the NICU was reduced by 3 dB from baseline. Mean (s.d.) baseline, phase 2, 3 and 4 noise levels in the two NICUs were: LAeq: 57.0 (0.84), 56.8 (1.6), 55.3 (1.9) and 54.5 (2.6) dB, respectively (P<0.01). Adherence with the planned process measure of 'quiet times' was >90%.

CONCLUSIONS

Implementing a multipronged QI initiative resulted in significant noise level reduction in two multipod NICUs. It is feasible to reduce noise levels if QI interventions are coupled with active engagement of the clinical staff and following continuous process of improvement methods, measurements and protocols.

Interparticle Reactions: An Emerging Direction in Nanomaterials Chemistry

Nanoparticles exhibit a rich variety in terms of structure, composition, and properties. However, reactions between them remain largely unexplored. In this Account, we discuss an emerging aspect of nanomaterials chemistry, namely, interparticle reactions in solution phase, similar to reactions between molecules, involving atomically precise noble metal clusters. A brief historical account of the developments, starting from the bare, gas phase clusters, which led to the synthesis of atomically precise monolayer protected clusters in solution, is presented first. Then a reaction between two thiolate-protected, atomically precise noble metal clusters, [Au₂₅(PET)₁₈]^- and [Ag₄₄(FTP)₃₀]^4- (PET = 2-phenylethanethiol, FTP = 4-fluorothiophenol), is presented wherein these clusters spontaneously exchange metal atoms, ligands, and metal-ligand fragments between them under ambient conditions. The number of exchanged species could be controlled by varying the initial compositions of the reactant clusters. Next, a reaction of [Au₂₅(PET)₁₈]^- with its structural analogue [Ag₂₅(DMBT)₁₈]^- (DMBT = 2,4-dimethylbenzenethiol) is presented, which shows that atom-exchange reactions happen with structures conserved. We detected a transient dianionic adduct, [Ag₂₅Au₂₅(DMBT)₁₈(PET)₁₈]^2-, formed between the two clusters indicating that this adduct could be a possible intermediate of the reaction. A reaction involving a dithiolate-protected cluster, [Ag₂₉(BDT)₁₂]^3- (BDT = 1,3-benzenedithiol), is also presented wherein metal atom exchange alone occurs, but with no ligand and fragment exchanges. These examples demonstrate that the nature of the metal-thiolate interface, that is, its bonding network and dynamics, play crucial roles in dictating the type of exchange processes and overall rates. We also discuss a recently proposed structural model of these clusters, namely, the Borromean ring model, to understand the dynamics of the metal-ligand interfaces and to address the site specificity and selectivity in these reactions. In the subsequent sections, reactions involving atomically precise noble metal clusters and one- and two-dimensional nanosystems are presented. We show that highly protected, stable clusters such as [Au₂₅(PET)₁₈]^- undergo chemical transformation on graphenic surfaces to form a bigger cluster, Au₁₃₅(PET)₅₇. Finally, we present the transformation of tellurium nanowires (Te NWs) to Ag-Te-Ag dumbbell nanostructures through a reaction with an atomically precise silver cluster, Ag₃₂(SG)₁₉ (SG = glutathione thiolate). The starting materials and the products were characterized using high resolution electrospray ionization mass spectrometry, matrix assisted laser desorption ionization mass spectrometry, UV/vis absorption, luminescence spectroscopies, etc. We have analyzed principally mass spectrometric data to understand these reactions. In summary, we present the emergence of a new branch of chemistry involving the reactions of atomically precise cluster systems, which are prototypical nanoparticles. We demonstrate that such interparticle chemistry is not limited to metal clusters; it occurs across zero-, one-, and two-dimensional nanosystems leading to specific transformations. We conclude this Account with a discussion of the limitations in understanding of these reactions and future directions in this area of nanomaterials chemistry.

Au22Ir3(PET)18: An Unusual Alloy Cluster through Intercluster Reaction

An intercluster reaction between Au₂₅(PET)₁₈ and Ir₉(PET)₆ producing the alloy cluster, Au₂₂Ir₃(PET)₁₈ exclusively, is demonstrated where the ligand PET is 2-phenylethanethiol. Typical reactions of this kind between Au₂₅(PET)₁₈ and Ag₂₅(SR)₁₈, and other clusters reported previously, produce mixed cluster products. The cluster composition was confirmed by detailed high-resolution electrospray ionization mass spectrometry (ESI MS) and other spectroscopic techniques. This is the first example of Ir metal incorporation in a monolayer-protected noble metal cluster. The formation of a single product was confirmed by thin layer chromatography (TLC). Density functional theory (DFT) calculations suggest that the most favorable geometry of the Au₂₂Ir₃(PET)₁₈ cluster is one wherein the three Ir atoms are arranged triangularly with one Ir atom at the icosahedral core and the other two on the icosahedral shell. Significant contraction of the metal core was observed due to strong Ir-Ir interactions.

Manifestation of Geometric and Electronic Shell Structures of Metal Clusters in Intercluster Reactions

Monolayer protected clusters exhibit rich diversity in geometric and electronic structures. However, structure-reactivity relationships in these clusters are rarely explored. In this context, [Ag₄₄(SR)₃₀]^4-, where -SR is an alkyl/aryl thiolate, is an interesting system due to its geometrically and electronically closed-shell structures and distinct charge states. We demonstrate that these structural features of [Ag₄₄(SR)₃₀]^4- are distinctly manifested in its solution-state reaction with another cluster, [Au₂₅(SR)₁₈]^-. Through this reaction, an alloy cluster anion, [Au₁₂Ag₃₂(SR)₃₀]^4-, evolves spontaneously as revealed by high-resolution electrospray ionization mass spectrometry. Ultraviolet-visible absorption spectroscopy and density functional theory calculations indicate that [Au₁₂Ag₃₂(SR)₃₀]^4- is formed by the substitution of all of the Ag atoms in the innermost icosahedral shell of [Ag₄₄(SR)₃₀]^4- and the abundance is attributed to its higher stability due to closed geometric as well as electronic shell structure, similar to the reactant clusters. We further demonstrate that the substitution of metal atoms in the middle dodecahedral shell and the outermost mount sites are also possible, however such substitutions produce Au_xAg_44-x(SR)₃₀ alloy clusters with geometrically and electronically open shells. Depending on specific sites of substitution, an unexpected superatom-nonsuperatom transition occurs in the distribution of Au_xAg_44-x(SR)₃₀ alloy clusters formed in this reaction. Our results present a unique example of a structure-reactivity relationship in the metal atom substitution chemistry of monolayer protected clusters, wherein a systematic trend, reflecting the geometric and the electronic shell structures of the reactant as well as the product clusters, was observed.

Cord blood lead level in an urban inner-city hospital

Lead levels were measured by inductively coupled plasma mass spectrometry (ICP-MS) in umbilical cord blood samples of 150 neonates in an urban inner-city hospital. The mean (SD) gestation and birth weight of our cohort were 38.8 (1.7) weeks and 3,217 (519) grams. There were 89% African-Americans, 53% males and 79% were born via vaginal delivery. Mean (SD) maternal age was 24.5 (5.8) years. History of drug abuse and smoking was reported in 8.7% and 10.7% respectively, with only 1 mother reporting a history of high lead level in childhood. Prenatal vitamin intake was reported in 99.3%. Cord blood lead level was available in 144 patients, with lead level of <1μg/dL seen in 141 (97.9%) and>1 in 3 (2.1%) patients. No patient had cord blood lead level of >2μg/dL. High lead levels during childhood in high-risk urban population, however, suggest the need for intensive efforts for prevention of environmental exposure to lead in early childhood.

ID: 80: IMPACT OF CYCLOOXYGENASE-2 DELETION ON ADIPOSE TISSUE INFLAMMATION AND SYSTEMIC METABOLIC HOMEOSTASIS IN OBESITY

Objective

Adipose tissue (AT) inflammation characterized by macrophage accumulation and secretion of inflammatory mediators is considered to play a critical role in the pathogenesis of obesity-linked metabolic disorders, in particular, insulin resistance. Although an intimate relationship exists between inflammation and metabolism, there is a lack of consistent therapeutic success in targeting inflammatory pathways to treat obesity-linked metabolic diseases suggesting that certain immunoregulatory genes can exert differential effects on metabolic regulation. The objective of this study is to determine the role of cyclooxygenase-2 (COX-2), an inducible inflammatory gene, abundantly upregulated in macrophages upon exposure to inflammatory stimuli, in modulating AT inflammation and systemic metabolic homeostasis in obesity.

Methods

Wild type (WT) and COX-2 knock-out (COX-2-/-) mice were fed a standard chow diet (CD) or a high fat (HF, 45% fat calories) diet for 13 wk. The expression of macrophage and inflammatory markers were determined in visceral AT and macrophage-rich stromal cells collected from visceral AT. In addition, various metabolic tests including insulin and glucose tolerance tests and energy expenditure measurements were performed to determine the impact of COX-2 deletion in modulating metabolic homeostasis.

Results

Consistent with its role in inducing an inflammatory response, deletion of COX-2 resulted in a decrease in markers of AT inflammation. For example, the markers of M1 pro-inflammatory macrophages were reduced and that of M2 anti-inflammatory macrophages were increased in the visceral AT of COX-2−/− compared to WT mice on a HF diet. Moreover, the mRNA expression of inflammatory genes such as MIP1α and TNFα was significantly lower (P<0.05) in COX-2−/− compared to WT mice. Although AT inflammation was reduced, COX-2 deletion led to impaired metabolic homeostasis. Notably, the total fat mass determined by EchoMRI was significantly higher (P<0.001) with a concomitant increase in visceral AT mass and plasma leptin levels (P<0.05) in COX-2−/− mice. In addition, the plasma total cholesterol was significantly higher (P<0.05) in COX-2−/− compared to WT mice on a HF diet. Moreover, COX-2−/− mice exhibit systemic insulin resistance and impaired glucose handling as analyzed by insulin and glucose tolerance tests. Further, the energy expenditure and locomotor activity determined using the metabolic cages were greatly reduced in COX-2−/− compared to WT mice.

Conclusion

Taken together, deletion of COX-2 attenuated AT inflammation but increased adiposity and impaired metabolic homeostasis in a state of nutrient excess. Although inflammation is intricately linked to metabolism, our study suggests that a considerable discordance exists between these two processes and that COX-2 derived eicosanoids can exert differential effects in modulating inflammatory and metabolic processes.

ID: 81: NANOFORMULATED COPPER/ZINC SUPEROXIDE DISMUTASE CAUSES MUSCLE METABOLIC ALTERATIONS AND IMPROVES SYSTEMIC INSULIN SENSITIVITY IN MICE

Oxidative stress mediates mitochondrial dysfunction and impairment of glucose metabolism in muscle thereby leading to systemic insulin resistance. In vivo studies have demonstrated that copper/zinc superoxide dismutase (Cu/ZnSOD)-deficient mice show oxidative damage in various organs including skeletal muscle. The objective of this study is to determine the role of nanoformulated Cu/ZnSOD (nanoSOD) in improving insulin sensitivity through effects inherent to muscle. Wild type mice were fed a standard chow diet for 10 weeks. A cohort of these mice received nanoSOD intraperitoneally at 1000 U/kg body weight once in two days for a period of 15 days. We noted that the fasting blood glucose level was significantly reduced in nanoSOD treated mice compared to control (P<0.05). Moreover, insulin tolerance test (ITT) revealed that nanoSOD treated mice showed improved glucose handling in response to insulin (0.75 U/kg body weight) compared to control mice. However, the response of these mice to acute glucose challenge as analyzed by glucose tolerance test was not different between groups. We next analyzed the muscle mRNA samples for genes involved in fatty acid metabolism. Interestingly, we noted that the expression of FASN and SREBP1, genes promoting fatty acid synthesis was significantly reduced in nanoSOD treated mice suggesting that de novo lipogenesis which can promote insulin resistance is reduced upon nanoSOD treatment. Further, the mRNA expression of PCX which promotes both gluconeogenesis and lipogenesis was significantly reduced (P<0.01) in nanoSOD treated mice compared to controls. Regarding genes regulating fatty acid metabolism, we noted that the expression of ACOX1, CPT1a, and CPT2, genes involved in mitochondrial fatty acid β-oxidation was reduced in nanoSOD treated mice. Interestingly, these metabolic changes were associated with reduced mRNA levels of inflammatory markers including TNFα, MMP12, and VCAM-1 in visceral adipose tissue in nanoSOD treated mice. However, in the liver, the mRNA level of genes involved in de novo lipogenesis and mitochondrial fatty acid β-oxidation was not altered upon nanoSOD treatment Taken together; our data demonstrate that nanoSOD improves systemic glucose handling which was associated with a reduction in de novo lipogenesis and fatty acid oxidation in muscle. Because fatty acid oversupply is a key mediator of muscle insulin resistance primarily via accumulation of fatty acid metabolites, our data suggest that changes in muscle fatty acid metabolism may play a role in mediating the effects of nanoSOD in improving systemic glucose handing and insulin resistance. .

Possible isomers in ligand protected Ag11cluster ions identified by ion mobility mass spectrometry and fragmented by surface induced dissociation

Isomeric glutathione protected silver clusters have been detected using ion mobility mass spectrometry. This cluster has been fragmented by conventional collision induced dissociation and newly introduced surface induced dissociation.

[Au25(SR)18]22−: a noble metal cluster dimer in the gas phase

Dimeric and trimeric Au₂₅(SR)₁₈ have been detected experimentally by electrospray ionization mass spectrometry (ESI MS) and separated by ion mobility (IM).

Short-term outcomes after perinatal hypoxic ischemic encephalopathy: a report from the Children's Hospitals Neonatal Consortium HIE focus group

OBJECTIVE

To characterize infants affected with perinatal hypoxic ischemic encephalopathy (HIE) who were referred to regional neonatal intensive care units (NICUs) and their related short-term outcomes.

STUDY DESIGN

This is a descriptive study evaluating the data collected prospectively in the Children's Hospital Neonatal Database, comprised of 27 regional NICUs within their associated children's hospitals. A consecutive sample of 945 referred infants born ⩾36 weeks' gestation with perinatal HIE in the first 3 days of life over approximately 3 years (2010-July 2013) were included. Maternal and infant characteristics are described. Short-term outcomes were evaluated including medical comorbidities, mortality and status of survivors at discharge.

RESULT

High relative frequencies of maternal predisposing conditions, cesarean and operative vaginal deliveries were observed. Low Apgar scores, profound metabolic acidosis, extensive resuscitation in the delivery room, clinical and electroencephalographic (EEG) seizures, abnormal EEG background and brain imaging directly correlated with the severity of HIE. Therapeutic hypothermia was provided to 85% of infants, 15% of whom were classified as having mild HIE. Electrographic seizures were observed in 26% of the infants. Rates of complications and morbidities were similar to those reported in prior clinical trials and overall mortality was 15%.

CONCLUSION

Within this large contemporary cohort of newborns with perinatal HIE, the application of therapeutic hypothermia and associated neurodiagnostic studies appear to have expanded relative to reported clinical trials. Although seizure incidence and mortality were lower compared with those reported in the trials, it is unclear whether this represented improved outcomes or therapeutic drift with the treatment of milder disease.

Supramolecular functionalization and concomitant enhancement in properties of Au(25) clusters

We present a versatile approach for tuning the surface functionality of an atomically precise 25 atom gold cluster using specific host-guest interactions between β-cyclodextrin (CD) and the ligand anchored on the cluster. The supramolecular interaction between the Au25 cluster protected by 4-(t-butyl)benzyl mercaptan, labeled Au25SBB18, and CD yielding Au25SBB18∩CDn (n = 1, 2, 3, and 4) has been probed experimentally using various spectroscopic techniques and was further analyzed by density functional theory calculations and molecular modeling. The viability of our method in modifying the properties of differently functionalized Au25 clusters is demonstrated. Besides modifying their optoelectronic properties, the CD moieties present on the cluster surface provide enhanced stability and optical responses which are crucial in view of the potential applications of these systems. Here, the CD molecules act as an umbrella which protects the fragile cluster core from the direct interaction with many destabilizing agents such as metal ions, ligands, and so on. Apart from the inherent biocompatibility of the CD-protected Au clusters, additional capabilities acquired by the supramolecular functionalization make such modified clusters preferred materials for applications, including those in biology.

Probing molecular solids with low-energy ions

Ion/surface collisions in the ultralow- to low-energy (1-100-eV) window represent an excellent technique for investigation of the properties of condensed molecular solids at low temperatures. For example, this technique has revealed the unique physical and chemical processes that occur on the surface of ice, versus the liquid and vapor phases of water. Such instrument-dependent research, which is usually performed with spectroscopy and mass spectrometry, has led to new directions in studies of molecular materials. In this review, we discuss some interesting results and highlight recent developments in the area. We hope that access to the study of molecular solids with extreme surface specificity, as described here, will encourage investigators to explore new areas of research, some of which are outlined in this review.

Impact of 'targeted' fluconazole prophylaxis for preterm neonates: efficacy of a highly selective approach?

OBJECTIVE

The objective of this study was to evaluate the efficacy of targeted intermittent fluconazole prophylaxis (FP) to high-risk preterm (PT) infants.

STUDY DESIGN

Observational pre-post cohort study (n=524). Targeted FP (3  mg  kg(-1)) was administered to PT infants (birth weights <1500  g and <6 weeks of age) who received broad-spectrum antibiotics for more than 2 days and had at least one additional risk factor for invasive candidiasis during the antibiotic administration period.

RESULT

Invasive candidiasis decreased significantly from 15.3 to 6.2% during the FP period. Duration of parenteral nutrition (15.5 vs 19.2 days), central line (12.7 vs 15.8 days) and necrotizing enterocolitis rates (7 vs 9.5%) were significantly higher in the FP period. FP was administered to 89 (31.3%) infants; the median (range) number of doses was four (1 to 24) and duration was 7 (1 to 38) days.

CONCLUSION

In the current study, targeted intermittent FP to a selected population of PT infants was efficacious in reducing the rate of invasive candidiasis, compared with historical controls.

Safety and efficacy of Trans-warmer mattress for preterm neonates: results of a randomized controlled trial

OBJECTIVE

To compare the admission temperatures, incidence of hypothermia and discharge outcomes of preterm neonates managed with Trans-warmer mattress (TWM) initiated in the delivery room (DR) and controls.

STUDY DESIGN

A prospective quasi-randomized controlled trial was performed between January and November 2009 on preterm neonates <32 weeks gestation. Infants in the intervention group were resuscitated and transported to neonatal intensive care unit (NICU) on a TWM, in addition to other measures recommended by the Neonatal Resuscitation Program.

RESULT

The mean (s.d.) gestational age 28.7 (3) vs 28.7 (2.4) weeks and birth weight 1151 (407) vs 1175 (413) g) were comparable in the intervention (n=53) and control (n=49) groups. Temperature of the DR, maternal temperature, 5 min Apgar score, mode of delivery, cord pH and need for resuscitation were similar in both groups. Temperature of neonates in the DR (36.3 vs 36.0 °C) was also similar. Admission temperature in the NICU was significantly higher 36.2 °C (0.8) vs 35.7 °C (0.8) and incidence of hypothermia (temperatures <36 °C) lower in the intervention group (34 vs 57%, P<0.05). TWM use was not associated with any adverse effects. On logistic regression, low birth weight, lack of use of TWM and low DR temperature were independently associated with admission hypothermia.

CONCLUSION

In this quasi-randomized controlled trial, the admission temperatures of preterm neonates on whom TWM was used were significantly higher compared to controls with a reduction in the incidence of hypothermia. A TWM initiated in the DR may be a simple efficacious method of reducing hypothermia in preterm neonates.

Echocardiographic measures of ventricular function and pulmonary artery size: prognostic markers of congenital diaphragmatic hernia?

OBJECTIVE

To compare echocardiographic measures of biventricular function and pulmonary artery size in infants with congenital diaphragmatic hernia (CDH) and normal controls, and examine their correlation, if any, with outcomes in CDH.

STUDY DESIGN

We included consecutive neonates (<1 month old) with CDH and term controls without structural heart defects. Clinical and outcomes data were recorded and echocardiograms evaluated for right ventricular (RV) and left ventricular (LV) myocardial performance index (MPI), cardiac output index (CI) and McGoon index, among others. Statistical analyses (SPSS version 17, SPSS, Chicago, IL, USA) included between-group comparisons, using analysis of variance and χ(2)-test and binary regression, with significance set at P<0.05.

RESULT

Infants with CDH (n=34) were comparable with controls (n=35) in their age, weight, gestational age and gender. CDH was left sided in 24 (70%) neonates. Extracorporeal membrane oxygenation (ECMO) was required in 15 (45%) neonates; 18 (53%) infants survived. MPIs, CI and eccentricity index in systole were significantly worse in the CDH group, compared with controls and among CDH infants who died, compared with survivors. Infants with CDH who died or needed ECMO had significantly impaired MPIs and CI than survivors. On regression analyses, LV CI and MPIs were independently associated with mortality.

CONCLUSION

Infants with CDH had significantly impaired ventricular function and pulmonary hypertension, compared with controls. In the CDH group, LV dysfunction was associated with death and adverse outcomes. Further studies incorporating echocardiographic indices as prognostic markers of CDH are warranted.

Impact of balloon atrial septostomy in neonates with transposition of great arteries

OBJECTIVE

To examine the impact of balloon atrial septostomy (BAS) on cardio-respiratory status, need for prostaglandin E(1) (PGE(1)) and postoperative outcomes in infants with transposition of great arteries (TGA).

STUDY DESIGN

Single-center retrospective review of consecutive neonates with dTGA.

RESULT

BAS was performed in 42 (70%) infants and resulted in a significant increase in minimum (61 to 76%) and maximum (80 to 90%) oxygen (O(2)) saturations and a drop in FiO(2). BAS was 'successful,' that is, PGE(1) was discontinued in 16 (38%) infants. Three infants died; four infants developed strokes, all of whom had undergone BAS. The duration of hospitalization, ventilation and O(2) need did not differ between infants without BAS, 'successful' BAS and unsuccessful BAS. PGE(1) duration correlated with duration of hospitalization, ventilation, O(2) need and peak respiratory severity score (P<0.03).

CONCLUSION

We speculate that limiting BAS for clinical hypoxemia and aggressive weaning of PGE(1) following BAS would improve outcomes.

Refractory neonatal candidemia and high-dose micafungin pharmacotherapy

OBJECTIVE

Preterm neonates with candidemia frequently have persistently positive blood cultures, despite the use of conventional antifungal therapy. Our institutional treatment protocol for invasive candidiasis incorporates lipid complex amphotericin B as initial therapy with the sequential addition of fluconazole and high-dose micafungin (10 mg kg(-1)) every 48 to 72 h, if cultures from a sterile site remain positive. Our study objectives were to compare the clinical profiles and outcomes of preterm neonates with candidemia that responded to or were refractory to conventional antifungals. We further evaluate the clinical efficacy of high-dose micafungin pharmacotherapy of refractory candidemia.

STUDY DESIGN

A chart review was performed on preterm infants (n=29) with invasive candidiasis and demographic, microbiologic and outcome data abstracted. Proportions and continuous variables were compared between the groups using Fisher's exact two-tailed test and t-test.

RESULT

The refractory (n=19) candidemia and early responder (n=10) groups had comparable mean (+/-s.d.) gestation, 27(+/-3.1) vs 27.8 (+/-2.7) weeks. The refractory group was administered antibiotics for a longer duration, 14.5 (+/-10.3) vs 7.1 (+/-5) days, had a preponderance of non-albicans infections, 11 (57.9%) vs 1 (10%) and were on enteral feeds > 20 ml kg(-1) day(-1) significantly less often (21 vs 70%). Mortality was significantly higher (53 vs 20%) and fungal clearance rates lower (63.1 vs 90%), with a longer duration to clearance in the group with refractory candidemia. Mean aspartate aminotransferase (AST) showed a statistically significant increase following micafungin treatment, although clinical significance remains unclear.

CONCLUSION

Candidemia refractory to conventional antifungals is associated with prolonged antibiotic use, lack of enteral nutritive feeds and non-albicans infection. Despite high-dose micafungin pharmacotherapy in combination with conventional antifungals, infants with refractory candidemia had high mortality and poor fungal clearance.

Translation regulatory factor RBM3 is a proto-oncogene that prevents mitotic catastrophe

RNA-binding proteins play a key role in post-transcriptional regulation of mRNA stability and translation. We have identified that RBM3, a translation regulatory protein, is significantly upregulated in human tumors, including a stage-dependent increase in colorectal tumors. Forced RBM3 overexpression in NIH3T3 mouse fibroblasts and SW480 human colon epithelial cells increases cell proliferation and development of compact multicellular spheroids in soft agar suggesting the ability to induce anchorage-independent growth. In contrast, downregulating RBM3 in HCT116 colon cancer cells with specific siRNA decreases cell growth in culture, which was partially overcome when treated with prostaglandin E(2), a product of cyclooxygenase (COX)-2 enzyme activity. Knockdown also resulted in the growth arrest of tumor xenografts. We have also identified that RBM3 knockdown increases caspase-mediated apoptosis coupled with nuclear cyclin B1, and phosphorylated Cdc25c, Chk1 and Chk2 kinases, implying that under conditions of RBM3 downregulation, cells undergo mitotic catastrophe. RBM3 enhances COX-2, IL-8 and VEGF mRNA stability and translation. Conversely, RBM3 knockdown results in loss in the translation of these transcripts. These data demonstrate that the RNA stabilizing and translation regulatory protein RBM3 is a novel proto-oncogene that induces transformation when overexpressed and is essential for cells to progress through mitosis.

New type of charged defect in amorphous chalcogenides

We report on density-functional-based tight-binding simulations of a series of amorphous arsenic sulfide models. In addition to the charged coordination defects previously proposed to exist in chalcogenide glasses, a novel defect pair, [As(4)](-)-[S(3)](+), consisting of a fourfold coordinated arsenic site in a seesaw configuration and a threefold coordinated sulfur site in a near-planar trigonal configuration, was found in several models. The valence-alternation pairs [S(3)](+)-S-1 are converted into [As(4)](-)-[S(3)](+) pairs under HOMO-to-LUMO electronic excitation. This structural transformation is accompanied by a decrease in the size of the HOMO-LUMO band gap, which suggests that such transformations could contribute to photodarkening in these materials.

Origin of the boson peak in systems with lattice disorder

The origin of the boson peak in models with force-constant disorder has been established by calculations using the coherent potential approximation. The analytical results obtained are supported by precise numerical solutions. The boson peak in the disordered system is associated with the lowest van Hove singularity in the spectrum of the reference crystalline system, pushed down in frequency by disorder-induced level-repelling and hybridization effects.

Cell cycle basis for the onset and progression of c-Myc-induced, TGFalpha-enhanced mouse mammary gland carcinogenesis

Using single and double transgenic mouse models, we investigated how c-Myc modulates the mammary epithelial cell cycle to induce cancer and how TGFalpha enhanced the process. In c-myc transgenic mice, c-myc expression was high in the hyperplastic mammary epithelium and in the majority of tumor areas. However, the tumors displayed focal areas of low expression of c-myc but high rates of proliferation. In contrast to E2F1 and cyclin A2, which were induced and co-localized with c-myc expression, induction of cyclins D1 and E occurred only in these tumor foci. Overexpression of cyclin D1 also occurred in the hyperplastic epithelium of tgfalpha-single and tgfalpha/c-myc-double transgenic mice. In tgfalpha/c-myc tumors, cells positive for cyclins D1 and E were randomly spread, without showing a reciprocal relationship to c-myc expression. In contrast to c-myc tumors, most tgfalpha/c-myc tumors showed undetectable levels of retinoblastoma protein (pRB), and the loss of pRB occurred in some cases at the mRNA level. These results suggest that E2F1 and cyclin A2 may be induced by c-Myc to mediate the onset of mammary cancer, whereas overexpression of cyclins D1 and E may occur later to facilitate tumor progression. TGFalpha may play its synergistic role, at least in part, by inducing cyclin D1 and facilitating the loss of pRB.

Increased DNA-binding activity of cis-1,1-cyclobutanedicarboxylatodiammineplatinum(II) (carboplatin) in the presence of nucleophiles and human breast cancer MCF-7 cell cytoplasmic extracts: activation theory revisited

The molecular mechanism of carboplatin [cis-1,1-cyclobutanedicarboxylatodiammineplatinum(II)] activation is still unresolved. We studied the binding of carboplatin to calf thymus DNA in the presence of thiourea, glutathione, and human breast cancer MCF-7 cell cytoplasmic extracts by measurement of DNA-dependent ethidium bromide fluorescence and atomic absorption spectroscopy. After a 96-hr period of reaction, the decrease in the DNA-dependent fluorescence yield of ethidium bromide due to the formation of platinum (Pt)-DNA adducts increased significantly in the presence of thiourea (6-fold) and glutathione (3- to 4-fold) as compared to the controls in the absence of the nucleophiles. There was also a marked elevation in the levels of platinum incorporated into DNA, measured by atomic absorption spectroscopy (2- to 3-fold and 5- to 7-fold for thiourea and glutathione, respectively). More remarkably, the Pt-DNA adducts formed in the presence of cytoplasmic extracts of MCF-7 human breast cancer cells also showed similar results in a dose-related fashion. Carboplatin, therefore, displayed a characteristic increase in DNA binding/damaging in the presence of the very same S-containing nucleophiles that showed the expected quenching effects in the case of cisplatin [cis-diamminedichloroplatinum (II)]. We propose a nucleophile-facilitated release of the active species of carboplatin prior to binding with DNA.

Helix-coil transitions in DNA by novel Pt(II) complexes: a pH melting study

Recent reports have shown that pH could also be used as a melting factor to monitor helix-coil transitions in DNA; the results being comparable to those obtained by Tm studies. The rapidity with which the method can be performed to obtain similar transition curves, and elimination of the evaporation factor (at high temperatures as seen in Tm studies) is one of the advantages offered by this technique. With regard to its suitability in studying DNA-drug interactions, the addition of platinum (II) complexes changed the Pm (pH of melting) in a predictable manner thereby confirming the destabilization of bases in DNA. In the present study, melting profiles of calf thymus DNA modified by certain chloro substituted platinum complexes have been generated using pH as a denaturing factor. These novel platinum complexes have been recently shown to have potential tumour inhibiting properties too. Diammine diaqua platinum (active form of the anti tumour drug cisplatin) was coupled to beta poly-L-malate (a bioresorbable polymer synthesized by a myxomycete), L-malate and L-succinate. At a constant Pt:P ratio (0.2), the extent of damage to DNA by these complexes in comparison to cisplatin was cisPt>SuccPt>MalPt>PMA-Pt>carboplatin. Given the similarity of the side groups of these platinum compounds with that of carboplatin (a successful second generation analog of cisplatin), interesting variations have been obtained in the DNA melting profiles, the implications of which have been discussed in the present study.

Myc/p53 interactions in transgenic mouse mammary development, tumorigenesis and chromosomal instability

We have examined defects in mammary development and tumorigenesis in a transgenic model expressing the c-myc gene under the MMTV-LTR promoter. The stochastic tumors which arise from hyperplastic ductal and lobular lesions in this model are characterized by high rates both of apoptosis and of chromosomal instability. Since the p53 gene product is thought to be central in the maintenance of genomic integrity, in part due to its ability to induce apoptosis in cells harboring DNA damage, we examined its expression and possible mutation. Initially, we observed that unmutated p53 is strongly expressed in premalignant mammary glands and in mammary tumors derived from the MMTV-c-myc strain. We then mated the MMTV-myc strain to a p53-deficient strain as a means of examining the effect of this lesion on mammary development and tumorigenesis in the context of c-myc overexpression. A lack of both p53 alleles in the presence of c-myc overexpression resulted in a dramatic hyerplastic alteration in mammary gland development. Specifically, in female bitransgenic MMTV-c-myc/p53 null mice (MMTV-myc/p53(-/-)), lobular hyperplasias were observed at almost every ductal end bud as early as 32 days of age. In contrast, only mild ductal and lobular hyperplasias were seen in MMTV-myc mice that contained both p53 alleles (MMTV-myc/p53(+/+)); an intermediate phenotype occurred in mice with a single intact (MMTV-myc/p53(+/-)) p53 allele. Mammary carcinomas arose with a high frequency in MMTV-myc/p53(+/-) mice; the tumors were comparable in frequency, histology and apoptotic index to the tumors in MMTV-myc/p53(+/+) mice. Also, as previously observed (Elson et al., 1995), lymphomas arose with extremely short latency in MMTV-myc/p53(-/-) mice, precluding study of the fate of their hyperplastic mammary lesions in situ. The frequency of p53 mutations in MMTV-myc/p53(+/+) and MMTV-myc/p53(+/-) mammary tumors and in cell lines derived from these tumors was examined by direct sequencing. No point mutations or deletions in p53 were observed in mammary tumors or cell lines from either genotype. Finally, a detailed chromosomal analysis using multicolor spectral karyotyping (SKY) revealed that there were multiple chromosomal alterations in the c-myc-overexpressing cells that contained either one or two unmutated p53 alleles. Variable ploidy changes, a common translocation of chromosome 11, and other chromosomal aberrations were observed. Our data thus support an interaction between c-Myc and p53 in mammary development, but suggest that loss of p53 is required neither for c-myc-dependent tumorigenesis nor for c-myc-dependent chromosomal instability.