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pH-Dependent Chiral Recognition of D- and L-Arginine Derived Polyamidoamino Acids by Self-assembled Sodium Deoxycholate. Polymers (Basel) 2020; 12:E900. [PMID: 32295002 PMCID: PMC7240376 DOI: 10.3390/polym12040900] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/09/2020] [Accepted: 04/10/2020] [Indexed: 01/27/2023] Open
Abstract
D- and L-arginine-based polyamidoamino acids, called D- and L-ARGO7, retain the chirality and acid/base properties of the parent -amino acids and show pH-dependent self-structuring in water. The ability of the ARGO7 chiral isomers to selectively interact with chiral biomolecules and/or surfaces was studied by choosing sodium deoxycholate (NaDC) as a model chiral biomolecule for its ability to self-assembly into globular micelles, showing enantio-selectivity. To this purpose, mixtures of NaDC with D-, L- or D,L-ARGO7, respectively, in water were analysed by circular dichroism (CD) spectroscopy and small-angle neutron scattering (SANS) at different levels of acidity expressed in terms of pD and concentrations. Differences in the CD spectra indicated chiral discrimination for NaDC/ARGO7 mixtures in the gel phase (pD 7.30) but not in the solution phase (pD 9.06). SANS measurements confirmed large scale structural perturbation induced by this chiral discrimination in the gel phase yet no modulation of the structure in the solution phase. Together, these techniques shed light on the mechanism by which ARGO7 stereoisomers modify the morphology of NaDC micelles as a function of pH. This work demonstrates chirality-dependent interactions that drive structural evolution and phase behaviour of NaDC, opening the way for designing novel smart drug delivery systems.
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Surfactant modulated interactions of hydrophobically modified ethoxylated urethane (HEUR) polymers with penetrable surfaces. J Colloid Interface Sci 2019; 552:9-16. [DOI: 10.1016/j.jcis.2019.05.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 11/15/2022]
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Surfactant modulated interaction of hydrophobically modified ethoxylated urethane (HEUR) polymers with impenetrable surfaces. J Colloid Interface Sci 2019; 539:126-134. [PMID: 30579216 DOI: 10.1016/j.jcis.2018.12.059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 12/08/2018] [Accepted: 12/15/2018] [Indexed: 11/27/2022]
Abstract
HYPOTHESIS The presence of surfactant modulates the surface-chemistry-specific interaction of hard colloidal particles (latex) with HEUR polymers, principally through introducing a preferential solution interaction rather than a competitive surface interaction; addition of surfactant leads to a preponderance of polymer/surfactant solution complexes rather than surface-bound complexes. EXPERIMENTS A range of model formulations comprising a hexyl end-capped urethane polymer (C6-L-(EO100-L)9-C6), sodium dodecylsulfate (SDS) and a series of polystyrene-butylacrylate latices (PS-BA-L) have been characterised in terms of rheology, particle surface area (solvent relaxation NMR), polymer conformation (small-angle neutron scattering) and solution composition to build up a detailed picture of the distribution of the HEUR in the presence of both surfactant and latex. FINDINGS There is very weak adsorption of C6-L-(EO100-L)9-C6 to only the most hydrophobic latex surface studied, an adsorption that is further weakened by the addition of low levels of surfactant. Macroscopic changes in the hydrophobic latex system may be interpreted in terms of bridging flocculation at low polymer concentrations. No adsorption of C6-L-(EO100-L)9-C6 is observed in the case of hydrophilic surfaces. In most cases, the observed behaviour of the ternary system (polymer/surfactant/particle) is highly reminiscent of the binary (polymer/surfactant) system at the appropriate composition, suggesting that the polymer/surfactant solution interaction is the dominant one.
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Studying the interaction of hydrophobically modified ethoxylated urethane (HEUR) polymers with sodium dodecylsulfate (SDS) in concentrated polymer solutions. J Colloid Interface Sci 2018; 529:588-598. [DOI: 10.1016/j.jcis.2018.06.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 06/17/2018] [Accepted: 06/19/2018] [Indexed: 11/25/2022]
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Circular dichroism studies of low molecular weight hydrogelators: The use of SRCD and addressing practical issues. Chirality 2018; 30:708-718. [PMID: 29645307 DOI: 10.1002/chir.22850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/08/2018] [Accepted: 02/14/2018] [Indexed: 11/08/2022]
Abstract
Circular dichroism (CD) spectroscopy has been used extensively for the investigation of the conformation and configuration of chiral molecules, but its use for evaluating the mode of self-assembly in soft materials has been limited. Herein, we report a protocol for the study of such materials by electronic CD spectroscopy using commercial/benchtop instruments and synchrotron radiation (SR) using the B23 beamline available at Diamond Light Source. The use of the B23 beamtime for SRCD was advantageous because of the unique enhanced spatial resolution achieved because of its highly collimated and small beamlight cross section (ca. 250 μm) and higher photon flux in the far UV region (175-250 nm) enhancing the signal-to-noise ratio relative to benchtop CD instruments. A set of low molecular weight (LMW) hydrogelators, comprising two Fmoc-protected enantiomeric monosaccharides and one Fmoc dipeptide (Fmoc-FF), were studied. The research focused on the optimization of sample preparation and handling, which then enabled the characterization of sample conformational homogeneity and thermal stability. CD spectroscopy, in combination with other spectroscopic techniques and microscopy, will allow a better insight into the self-assembly of chiral building blocks into higher order structural architectures.
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3D printed microneedles for insulin skin delivery. Int J Pharm 2018; 544:425-432. [PMID: 29555437 DOI: 10.1016/j.ijpharm.2018.03.031] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 02/20/2018] [Accepted: 03/15/2018] [Indexed: 01/01/2023]
Abstract
In this study, polymeric microneedle patches were fabricated by stereolithography, a 3D printing technique, for the transdermal delivery of insulin. A biocompatible resin was photopolymerized to build pyramid and cone microneedle designs followed by inkjet print coating of insulin formulations. Trehalose, mannitol and xylitol were used as drug carriers with the aim to preserve insulin integrity and stability but also to facilitate rapid release rates. Circular dichroism and Raman analysis demonstrated that all carriers maintained the native form of insulin, with xylitol presenting the best performance. Franz cell release studies were used for in vitro determination of insulin release rates in porcine skin. Insulin was released rapidly within 30 min irrespectively of the microneedle design. 3D printing was proved an effective technology for the fabrication of biocompatible and scalable microneedle patches.
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Facet-Dependent Interactions of Islet Amyloid Polypeptide with Gold Nanoparticles: Implications for Fibril Formation and Peptide-Induced Lipid Membrane Disruption. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2017; 29:1550-1560. [PMID: 28260837 PMCID: PMC5333186 DOI: 10.1021/acs.chemmater.6b04144] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 01/25/2017] [Indexed: 05/03/2023]
Abstract
A comprehensive understanding of the mechanisms of interaction between proteins or peptides and nanomaterials is crucial for the development of nanomaterial-based diagnostics and therapeutics. In this work, we systematically explored the interactions between citrate-capped gold nanoparticles (AuNPs) and islet amyloid polypeptide (IAPP), a 37-amino acid peptide hormone co-secreted with insulin from the pancreatic islet. We utilized diffusion-ordered spectroscopy, isothermal titration calorimetry, localized surface plasmon resonance spectroscopy, gel electrophoresis, atomic force microscopy, transmission electron microscopy (TEM), and molecular dynamics (MD) simulations to systematically elucidate the underlying mechanism of the IAPP-AuNP interactions. Because of the presence of a metal-binding sequence motif in the hydrophilic peptide domain, IAPP strongly interacts with the Au surface in both the monomeric and fibrillar states. Circular dichroism showed that AuNPs triggered the IAPP conformational transition from random coil to ordered structures (α-helix and β-sheet), and TEM imaging suggested the acceleration of IAPP fibrillation in the presence of AuNPs. MD simulations revealed that the IAPP-AuNP interactions were initiated by the N-terminal domain (IAPP residues 1-19), which subsequently induced a facet-dependent conformational change in IAPP. On a Au(111) surface, IAPP was unfolded and adsorbed directly onto the Au surface, while for the Au(100) surface, it interacted predominantly with the citrate adlayer and retained some helical conformation. The observed affinity of AuNPs for IAPP was further applied to reduce the level of peptide-induced lipid membrane disruption.
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Hemorrhagic Herpes Simplex Virus Type 1 Nephritis: An Unusual Cause of Acute Allograft Dysfunction. Am J Transplant 2017; 17:287-291. [PMID: 27545820 DOI: 10.1111/ajt.14022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 08/16/2016] [Accepted: 08/17/2016] [Indexed: 01/25/2023]
Abstract
Interstitial nephritis due to viruses is well-described after solid organ transplantation. Viruses implicated include cytomegalovirus; BK polyomavirus; Epstein-Barr virus; and, less commonly, adenovirus. We describe a rare case of hemorrhagic allograft nephritis due to herpes simplex virus type 1 at 10 days after living donor kidney transplantation. The patient had a favorable outcome with intravenous acyclovir and reduction of immunosuppression.
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An in vitro evaluation of epigallocatechin gallate (eGCG) as a biocompatible inhibitor of ricin toxin. Biochim Biophys Acta Gen Subj 2016; 1860:1541-50. [DOI: 10.1016/j.bbagen.2016.03.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 03/10/2016] [Accepted: 03/20/2016] [Indexed: 10/22/2022]
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Monitoring real time polymorphic transformation of sulfanilamide by diffuse reflectance visible spectroscopy. J Pharm Anal 2016; 6:179-183. [PMID: 29403979 PMCID: PMC5762491 DOI: 10.1016/j.jpha.2015.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 12/17/2015] [Accepted: 12/18/2015] [Indexed: 11/30/2022] Open
Abstract
This study investigated the development of a novel approach to surface characterization of drug polymorphism and the extension of the capabilities of this method to perform ‘real time’ in situ measurements. This was achieved using diffuse reflectance visible (DRV) spectroscopy and dye deposition, using the pH sensitive dye, thymol blue (TB). Two polymorphs, SFN-β and SFN-γ, of the drug substance sulfanilamide (SFN) were examined. The interaction of adsorbed dye with polymorphs showed different behavior, and thus reported different DRV spectra. Consideration of the acid/base properties of the morphological forms of the drug molecule provided a rationalization of the mechanism of differential coloration by indicator dyes. The kinetics of the polymorphic transformation of SFN polymorphs was monitored using treatment with TB dye and DRV spectroscopy. The thermally-induced transformation fitted a first-order solid-state kinetic model (R2=0.992), giving a rate constant of 2.43×10−2 s−1.
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Hepatitis B core antibody-positive donors in cardiac transplantation: a single-center experience. Transpl Infect Dis 2014; 16:859-63. [PMID: 25154437 DOI: 10.1111/tid.12280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 05/03/2014] [Accepted: 06/01/2014] [Indexed: 01/15/2023]
Abstract
Hepatitis B virus (HBV) core antibody (HBcAb)-positive donors are increasingly utilized in solid organ transplantation. We report a single center's experience in cardiac transplantation with 18 HBcAb-positive donors. Available follow-up on recipients of cardiac allografts from HBcAb-positive donors, including 2 donors with low-level serum HBV DNA at the time of transplantation, demonstrated no documented donor-derived HBV transmission.
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Endemic fungal infections in solid organ and hematopoietic cell transplant recipients enrolled in the Transplant-Associated Infection Surveillance Network (TRANSNET). Transpl Infect Dis 2014; 16:213-24. [PMID: 24589027 DOI: 10.1111/tid.12186] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 06/03/2013] [Accepted: 08/03/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND Invasive fungal infections are a major cause of morbidity and mortality among solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients, but few data have been reported on the epidemiology of endemic fungal infections in these populations. METHODS Fifteen institutions belonging to the Transplant-Associated Infection Surveillance Network prospectively enrolled SOT and HCT recipients with histoplasmosis, blastomycosis, or coccidioidomycosis occurring between March 2001 and March 2006. RESULTS A total of 70 patients (64 SOT recipients and 6 HCT recipients) had infection with an endemic mycosis, including 52 with histoplasmosis, 9 with blastomycosis, and 9 with coccidioidomycosis. The 12-month cumulative incidence rate among SOT recipients for histoplasmosis was 0.102%. Occurrence of infection was bimodal; 28 (40%) infections occurred in the first 6 months post transplantation, and 24 (34%) occurred between 2 and 11 years post transplantation. Three patients were documented to have acquired infection from the donor organ. Seven SOT recipients with histoplasmosis and 3 with coccidioidomycosis died (16%); no HCT recipient died. CONCLUSIONS This 5-year multicenter prospective surveillance study found that endemic mycoses occur uncommonly in SOT and HCT recipients, and that the period at risk extends for years after transplantation.
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Improved solid-phase synthesis and study of arylopeptoids with conformation-directing side chains. Tetrahedron 2012. [DOI: 10.1016/j.tet.2011.12.049] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Evaluation of a digital microfluidic real-time PCR platform to detect DNA of Candida albicans in blood. Eur J Clin Microbiol Infect Dis 2012; 31:2237-45. [PMID: 22327343 DOI: 10.1007/s10096-012-1561-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Accepted: 01/18/2012] [Indexed: 11/24/2022]
Abstract
Species of Candida frequently cause life-threatening infections in neonates, transplant and intensive care unit (ICU) patients, and others with compromised host defenses. The successful management of systemic candidiasis depends upon early, rapid diagnosis. Blood cultures are the standard diagnostic method, but identification requires days and less than half of the patients are positive. These limitations may be eliminated by using real-time polymerase chain reaction (PCR) to detect Candida DNA in the blood specimens of patients at risk. Here, we optimized a PCR protocol to detect 5-10 yeasts in low volumes of simulated and clinical specimens. We also used a mouse model of systemic candidiasis and determined that candidemia is optimally detectable during the first few days after infection. However, PCR tests are often costly, labor-intensive, and inconvenient for routine use. To address these obstacles, we evaluated the innovative microfluidic real-time PCR platform (Advanced Liquid Logic, Inc.), which has the potential for full automation and rapid turnaround. Eleven and nine of 16 specimens from individual patients with culture-proven candidemia tested positive for C. albicans DNA by conventional and microfluidic real-time PCR, respectively, for a combined sensitivity of 94%. The microfluidic platform offers a significant technical advance in the detection of microbial DNA in clinical specimens.
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Effect of capping groups at the N- and C-termini on the conformational preference of α,β-peptoids. Org Biomol Chem 2012; 10:1108-22. [DOI: 10.1039/c1ob06386c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Cyclic α,β-peptoid octamers with differing side chain patterns: synthesis and conformational investigation. Amino Acids 2011; 41:663-72. [DOI: 10.1007/s00726-011-0887-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 03/08/2011] [Indexed: 11/28/2022]
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Abstract
Two patients developed renal mucormycosis following transplantation of kidneys from the same donor, a near-drowning victim in a motor vehicle crash. Genotypically, indistinguishable strains of Apophysomyces elegans were recovered from both recipients. We investigated the source of the infection including review of medical records, environmental sampling at possible locations of contamination and query for additional cases at other centers. Histopathology of the explanted kidneys revealed extensive vascular invasion by aseptate, fungal hyphae with relative sparing of the renal capsules suggesting a vascular route of contamination. Disseminated infection in the donor could not be definitively established. A. elegans was not recovered from the same lots of reagents used for organ recovery or environmental samples and no other organ transplant-related cases were identified. This investigation suggests either isolated contamination of the organs during recovery or undiagnosed disseminated donor infection following a near-drowning event. Although no changes to current organ recovery or transplant procedures are recommended, public health officials and transplant physicians should consider the possibility of mucormycosis transmitted via organs in the future, particularly for near-drowning events. Attention to aseptic technique during organ recovery and processing is re-emphasized.
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Systemic Concentrations of Endogenous and Exogenous FSH in Anoestrous Ewes Superstimulated with Folltropin®-V. Reprod Domest Anim 2009; 44:353-8. [PMID: 19055560 DOI: 10.1111/j.1439-0531.2008.01124.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Vibrational spectroscopy and DFT calculations of the di-amino acid peptide l-aspartyl-l-glutamic acid in the zwitterionic state. Phys Chem Chem Phys 2009; 11:6389-400. [DOI: 10.1039/b903131f] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Remediation of a chlorinated aromatic hydrocarbon in water by photoelectrocatalysis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2009; 157:72-76. [PMID: 18789564 DOI: 10.1016/j.envpol.2008.07.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 07/29/2008] [Indexed: 05/26/2023]
Abstract
Photoelectrocatalysis driven by visible light offers a new and potentially powerful technology for the remediation of water contaminated by organo-xenobiotics. In this study, the performance of a visible light-driven photoelectrocatalytic (PEC) batch reactor, applying a tungsten trioxide (WO(3)) photoelectrode, to degrade the model pollutant 2,4-dichlorophenol (2,4-DCP) was monitored both by toxicological assessment (biosensing) and chemical analysis. The bacterial biosensor used to assess the presence of toxicity of the parent molecule and its breakdown products was a multicopy plasmid lux-marked E. coli HB101 pUCD607. The bacterial biosensor traced the removal of 2,4-DCP, and in some case, its toxicity response suggests the identification of transient toxic intermediates. The loss of the parent molecule, 2,4-DCP determined by HPLC, corresponded to the recorded photocurrents. Photoelectrocatalysis offers considerable potential for the remediation of chlorinated hydrocarbons, and that the biosensor based toxicity results identified likely compatibility of this technology with conventional, biological wastewater treatment.
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Spectroscopic studies of oligomers containing 2,5-trans furanoid sugar amino acids. Chirality 2008; 20:969-72. [PMID: 18311778 DOI: 10.1002/chir.20538] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Sugar amino acids and their oligomers, known as carbopeptoids, are commonly studied as foldamers. However, study of their conformational preference is often challenging when the adopted conformations are extended and/or disordered. This study is the first to explore the disordered nature of such carbopeptoids by utilizing a family of 2,5-trans carbopeptoids. An array of spectroscopic techniques has been used to investigate the conformational preference of these carbopeptoids. However, using this data alone it has not been possible to assign conformational preference as an ordered extended conformation or as a disordered family of closely related conformations. Computational methods need to be employed to achieve reliable interpretation of the spectroscopic data.
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DFT calculations of the structures and vibrational spectra of the [Fe(bpy)3]2+ and [Ru(bpy)3]2+ complexes. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2008.05.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Survival after lung transplantation of cystic fibrosis patients infected with Burkholderia cepacia complex. Am J Transplant 2008; 8:1025-30. [PMID: 18318775 DOI: 10.1111/j.1600-6143.2008.02186.x] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Within the Burkholderia cepacia complex (Bcc), B. cenocepacia portends increased mortality compared with other species. We investigated the impact of Bcc infection on mortality and re-infection following lung transplant (LT). Species designation for isolates from Bcc-infected patients was determined using 16S rDNA and recA gene analyses. Of 75 cystic fibrosis patients undergoing LT from September 1992 to August 2002, 59 had no Bcc and 16 had Bcc (including 7 B. cenocepacia) isolated in the year before LT. Of the latter, 87.5% had Bcc recovered after transplantation, and all retained their pretransplant strains. Survival was 97%, 92%, 76% and 63% for noninfected patients; 89%, 89%, 67% and 56% for patients infected with Bcc species other than B. cenocepacia; and 71%, 29%, 29% and 29% for patients with B. cenocepacia (p = 0.014) at 1 month, 1 year, 3 years and 5 years, respectively. Patients infected with B. cenocepacia before transplant were six times more likely to die within 1 year of transplant than those infected with other Bcc species (p = 0.04) and eight times than noninfected patients (p < 0.00005). Following LT, infection with Bcc species other than B. cenocepacia does not significantly impact 5-year survival whereas infection with B. cenocepacia pretransplant is associated with decreased survival.
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Multicenter retrospective development and validation of a clinical prediction rule for nosocomial invasive candidiasis in the intensive care setting. Eur J Clin Microbiol Infect Dis 2008; 26:271-6. [PMID: 17333081 DOI: 10.1007/s10096-007-0270-z] [Citation(s) in RCA: 285] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The study presented here was performed in order to create a rule that identifies subjects at high risk for invasive candidiasis in the intensive care setting. Retrospective review and statistical modelling were carried out on 2,890 patients who stayed at least 4 days in nine hospitals in the USA and Brazil; the overall incidence of invasive candidiasis in this group was 3% (88 cases). The best performing rule was as follows: Any systemic antibiotic (days 1-3) OR presence of a central venous catheter (days 1-3) AND at least TWO of the following-total parenteral nutrition (days 1-3), any dialysis (days 1-3), any major surgery (days -7-0), pancreatitis (days -7-0), any use of steroids (days -7-3), or use of other immunosuppressive agents (days -7-0). The rate of invasive candidiasis among patients meeting the rule was 9.9%, capturing 34% of cases in the units, with the following performance: relative risk 4.36, sensitivity 0.34, specificity 0.90, positive predictive value 0.01, and negative predictive value 0.97. The rule may identify patients at high risk of invasive candidiasis.
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Ovarian Responses, Hormonal Profiles and Embryo Yields in Anoestrous Ewes Superovulated with Folltropin®-V after Pretreatment with Medroxyprogesterone Acetate-releasing Vaginal Sponges and a Single Dose of Oestradiol-17β. Reprod Domest Anim 2007; 43:299-307. [DOI: 10.1111/j.1439-0531.2007.00894.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
Clostridium difficile-associated diarrhea (CDAD) has a wide spectrum of disease severity. Studies have implicated immunosuppressants as a risk factor for severe disease. We hypothesized that solid organ transplant (SOT) patients with CDAD would be at greater risk for severe disease because of their profound immunosuppression. Adult SOT patients with CDAD seen at Duke University Medical Center between 1999 and 2003 were compared with a reference group of non-transplant patients with CDAD. The primary outcome was the development of complicated colitis defined as death, intensive care unit admission, or urgent colectomy within 30 days of diagnosis. A secondary outcome was relapse within 60 days. Eighty transplant and 86 non-transplant cases were reviewed. There was no significant difference in the development of complicated colitis (13.8% vs. 7.0%) or relapse rates (6.2% vs. 7.0%) between the 2 groups. In the entire sample, 18.5% of patients receiving corticosteroids unrelated to transplantation relapsed as compared with 4.5% not receiving corticosteroids (risk ratio 4.3, P=0.02). In conclusion, no significant difference was found in severity of CDAD between SOT patients and non-transplant patients. Exposure to corticosteroids was significantly associated with an increased risk of relapse and may warrant a longer treatment course.
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Abstract
OBJECTIVE The purpose of this study was to examine the frequency of normal cerebrospinal fluid (CSF) parameters in Candida meningitis and the proportion of candidemia associated with Candida meningitis. STUDY DESIGN We evaluated the initial lumbar puncture results from infants discharged from 150 Neonatal Intensive Care Units between 1997 and 2004. Candida meningitis was diagnosed by a positive CSF culture or positive Gram stain for yeast. We calculated two-tailed P-values using non-parametric testing, Mann-Whitney, Kruskal-Wallis or Fisher's exact tests where appropriate. RESULTS Twenty infants had culture-positive Candida meningitis. Normal CSF parameters were found in 43% (3/7) of the infants with Candida meningitis and only 37% (7/19) of them had positive blood cultures for Candida. CONCLUSION Normal CSF parameters do not exclude the diagnosis of neonatal Candida meningitis. The majority of infants in this cohort with Candida meningitis did not have evidence of candidemia at the time of diagnosis.
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Non-comparative evaluation of the safety of aerosolized amphotericin B lipid complex in patients undergoing allogeneic hematopoietic stem cell transplantation. Transpl Infect Dis 2006; 8:13-20. [PMID: 16623816 DOI: 10.1111/j.1399-3062.2006.00125.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Allogeneic hematopoietic stem cell transplant (HSCT) recipients are at increased risk for invasive fungal infections (IFIs) over prolonged periods of time. Aerosolized amphotericin B lipid complex (ABLC) has shown promise in lung transplant recipients as a convenient means of delivering protective drug to the upper airways avoiding systemic toxicities. The safety and tolerability of aerosolized ABLC in 40 subjects undergoing allogeneic HSCT was prospectively investigated in an open-labeled, non-comparative study. Subjects received aerosolized ABLC treatment once daily for 4 days, then once weekly for 13 weeks; fluconazole was administered daily as standard of care through post-transplant day 100. Pulmonary mechanics were measured before and after each dose of inhaled ABLC; adverse events (AEs) and the development of IFI were also monitored. Cough, nausea, taste disturbance, or vomiting followed 2.2% of 458 total inhaled ABLC administrations; 5.2% of inhaled ABLC administrations were associated with >or=20% decrease in pulmonary function measurements (forced expiratory volume in 1 second or forced vital capacity) and none required treatment with bronchodilators or withdrawal from study. Four mild AEs were considered possibly or probably related to study treatment; no deaths or withdrawals from treatment were attributed to study drug. Of 3 proven IFIs occurring during the study period, only 1, a catheter-related case of disseminated fusariosis, occurred while the subject was receiving study medication. Aerosolized ABLC was well tolerated in allogeneic HSCT recipients. With only 1 of 40 subjects developing IFI while receiving treatment, the combination of fluconazole and inhaled ABLC warrants further study as antifungal prophylaxis following allogeneic HSCT.
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Electrochromic and photoelectrochemical characteristics of nanostructured WO3 films prepared by a sol–gel method. CR CHIM 2006. [DOI: 10.1016/j.crci.2005.02.044] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Multicenter evaluation of a Candida albicans peptide nucleic acid fluorescent in situ hybridization probe for characterization of yeast isolates from blood cultures. J Clin Microbiol 2005; 43:2909-12. [PMID: 15956416 PMCID: PMC1151928 DOI: 10.1128/jcm.43.6.2909-2912.2005] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We evaluated aliquots from 244 clinical blood culture bottles that demonstrated yeasts on Gram stain using a Candida albicans peptide nucleic acid (PNA) fluorescent in situ hybridization (FISH) probe. The sensitivity, specificity, positive predictive value, and negative predictive value of the C. albicans PNA FISH test in this study were 99%, 100%, 100%, and 99.3%, respectively.
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Photoelectrochemical Oxidation of Water at Transparent Ferric Oxide Film Electrodes. J Phys Chem B 2005; 109:13685-92. [PMID: 16852715 DOI: 10.1021/jp051546g] [Citation(s) in RCA: 246] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The fabrication of thin-film Fe(2)O(3) photoanodes from the spray pyrolysis of Fe(III)-containing solutions is reported along with their structural characterization and application to the photoelectrolysis of water. These films combine good performance, measured in terms of photocurrent density, with excellent mechanical stability. A full investigation into the effects that modifications of the spray-pyrolysis method, such as the addition of dopants or structure-directing agents and changes in precursor species or carrier solvent, have on the performance of the photoanodes has been realized. The largest photocurrents were obtained from photoanodes prepared from ferric chloride precursor solutions, simultaneously doped with Ti(4+) (5%) and Al(3+) (1%). Doping with Zn(2+) also shows promise, cathodically shifting the onset potential by approximately 0.22 V.
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Chemical Interactions in the Surface-Enhanced Resonance Raman Scattering of Ruthenium Polypyridyl Complexes. J Phys Chem B 2005; 109:3310-8. [PMID: 16851358 DOI: 10.1021/jp0485690] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Surface-enhanced resonance Raman scattering (SERRS) from the alpha-diimine complexes [Ru(bpm)(3)](2+) and [Ru(bpz)(3)](2+) is reported for the first time at a roughened silver electrode. In both cases, a possible adsorbate orientation has been proposed involving binding through nitrogen lone pair electrons to the silver surface, based on changes in band positions upon adsorption. The SERRS spectra of [Ru(bpm)(3)](2+) were found to change slightly with a change in applied potential. The relative intensity of the nu(C6C6') band was found to be dependent on both excitation wavelength and applied potential. This was ascribed to an active charge transfer (CT) mechanism operating synergistically with the electromagnetic mechanism. No such CT activity was observed in [Ru(bpz)(3)](2+). It is tentatively suggested that this behavior may arise from the different modes of adsorption of the two complexes.
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A SERRS spectroscopic investigation of nickel(ii) porphyrin complexes adsorbed at electrochemical interfaces. Phys Chem Chem Phys 2004. [DOI: 10.1039/b401817f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ab Initio Calculations and Normal Coordinate Analysis of Ruthenium Tris-α-diimine Complexes. Inorg Chem 2003; 43:342-50. [PMID: 14704086 DOI: 10.1021/ic034721l] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
For the first time, a full scaled quantum chemical normal coordinate analysis has been performed on [Ru(LL')(3)](2+) complexes, where LL' = 2,2'-bipyrazine (bpz) or 2,2'-bipyrimidine (bpm). Geometric structures were fully optimized using density functional theory and an effective core potential basis set. The infrared and Raman spectra were calculated using the optimized geometries. The results of the calculations provide a highly satisfactory fit to the experimental infrared and Raman spectra, and the potential energy distributions allow a detailed understanding of the vibrational bands therein.
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Ab Initio Calculations of the Structures and Vibrational Spectra of Ethene Complexes. J Phys Chem A 2003. [DOI: 10.1021/jp0357020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
The dramatic increase in nosocomial invasive mycoses over the past two decades has led to increased interest in the area of antifungal development. Unfortunately, the infusion of new diagnostic technology into the clinical mycology laboratory has lagged behind. Although newer, automated, continuous-monitoring blood culture systems are as sensitive as the older, manual "gold standard" system, the recovery of fungi from blood, as well as other clinical specimens, remains an insensitive marker for invasive fungal infection. Antigen assays for the rapid diagnosis of invasive fungal infections are in development, and galactomannan and glucan are two such promising antigens. Glucan may be present in the blood of patients with infection secondary to a wide variety of fungal pathogens, including Candida, Aspergillus, Fusarium, Saccharomyces, Trichosporon and Acremonium species. Early data suggest galactomannan may be present in the blood in detectable levels very early in the course of invasive aspergillosis. The galactomannan assay currently undergoing evaluations may actually be positive prior to the clinical suspicion for infection and may be useful in monitoring therapeutic response as well; however, the etiology of false-positive results following cytotoxic chemotherapy still has to be elucidated. PCR assays are also being developed in the research laboratory, however, the PCR assays will require a significant amount of adaptation and validation before they are ready for clinical care. Well-planned studies to evaluate the performance characteristics as well as appropriate clinical and cost-effective application of these new tests are needed.
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Heterobimetallic gold-iridium, silver-iridium, and gold-ruthenium bis(.mu.-hydrido) complexes. X-ray crystal and molecular structures of [AuRu(H)2(dppm)2(PPh3)]PF6 and [Ir(H)2(bpy)(PPh3)2]PF6. Inorg Chem 2002. [DOI: 10.1021/ic00268a019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Synthesis and characterization of cationic gold-rhodium phosphite cluster complexes. X-ray crystal and molecular structure of {Au4Rh(H)2[P(O-iso-C3H7)3]2(PPh3)4}PF6. Inorg Chem 2002. [DOI: 10.1021/ic00332a005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Heterobimetallic gold-osmium and gold-ruthenium hydrido complexes. X-ray crystal and molecular structures of [Au2Os(H)3(PPh3)5]PF6 and [AuRu(H)2(CO)(PPh3)4]PF6. Inorg Chem 2002. [DOI: 10.1021/ic00292a011] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mixed-metal gold phosphine cluster complexes and their reactivity toward triphenylphosphine. Inorg Chem 2002. [DOI: 10.1021/ic00262a040] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hospital management of tuberculosis in a region with a low incidence of tuberculosis and a high prevalence of nontuberculous mycobacteria. Infect Control Hosp Epidemiol 2001; 22:715-7. [PMID: 11842993 DOI: 10.1086/501851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We prospectively assessed the management of patients with suspected tuberculosis (TB) in an area with a high prevalence of nontuberculous mycobacteria (NTM) and a low incidence of TB. Clinicians' assessments were sensitive for TB but had poor predictive value. The acid-fast smear was a weak predictor of TB, owing to a high rate of isolation of NTM.
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Abstract
Lung transplantation is associated with a high incidence of infection which directly impacts the morbidity and mortality associated with the procedure. In addition, these infections may also have immunologic consequences that play a role in the evolution of lung injury syndromes, resulting in earlier loss of graft than otherwise would be expected to occur. Although bacteria are responsible for the majority of infections following lung transplantation, fungal infections are associated with the highest mortality. This paper is an overview of the major infectious complications encountered in the lung transplant population. The epidemiology, prophylaxis, and treatment of infections following lung transplantation are critical areas for continued research.
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Abstract
Viral infections are a leading cause of posttransplantation morbidity and mortality. A number of recent developments have altered our understanding and management of these disorders. The pathogenetic roles of several viruses, including human herpesviruses 6 and 8, have been newly established. Molecular-based diagnostic tests now make more rapid diagnosis possible. The licensing of new potent antiviral agents offers a wider choice of drugs for viral prophylaxis and treatment. The use of more potent immunosuppressive agents is responsible in part for the increasing incidence of some viral infections, but this varies among drugs, and individual viruses differ in their sensitivity to immunosuppressive agents. This review summarizes the natural history, diagnosis, prevention, and treatment of many common viral infections after renal transplantation.
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Significance of blood stream infection after lung transplantation: analysis in 176 consecutive patients. Transplantation 2000; 69:2360-6. [PMID: 10868641 DOI: 10.1097/00007890-200006150-00025] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Although infection is a leading cause of death after lung transplantation, very little is known about the incidence, epidemiology, and clinical significance of bloodstream infections in lung transplant recipients. METHODS All blood cultures were reviewed in 176 consecutive lung transplant recipients over a 6-year period. Data were obtained from a prospectively collected microbiological database. RESULTS Bloodstream infection (BSI) occurred in 25% (44/176) of all lung transplant recipients over the 6-year study period. Staphylococcus aureus, Pseudomonas aeruginosa, and Candida species were the most common bloodstream isolates after lung transplantation. The epidemiology of posttransplant BSI, however, varied considerably between early and late posttransplant time periods and also differed between cystic fibrosis (CF) and non-CF patients. BSI infection after transplantation was associated with significantly worse survival by Kaplan-Meir analysis (P value log rank test=0.0001). In a multivariable logistic regression model, posttransplant BSI was a significant predictor of posttransplant death (odds ratio 5.62, CI 2.41-13.11, P=0.001), independent of other pre- and posttransplant factors. CONCLUSIONS Bloodstream infection represents a serious complication after lung transplantation, occurring more frequently than previously recognized, and independently contributing to posttransplant mortality.
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Abstract
Medical advances have led to increased numbers of immunocompromised patients living longer. Coinciding with this increase in the immunocompromised patient population is an increase in the number of clinically significant fungal infections. Unfortunately, widespread use of the limited numbers of antifungal agents to treat these infections has led to the development of drug resistance. Thus, in an attempt to sort out the mechanisms of resistance for each of the systemically useful antifungal agents, a comprehensive review of the literature has been carried out. The most common mechanisms for the development of resistance involve changes in the enzymatic pathways which serve as the drug targets. For instance, changes in enzymes responsible for the biosynthesis of ergosterol, the target of azole activity, lead to azole resistance. Another common mechanism used by fungi to avoid drug toxicity includes reduced intracellular accumulation of the drug through both decreased permeability and energy-dependent efflux pumps. Using our current understanding of the mechanisms of drug resistance as a template, several strategies to overcome resistance have been identified. These include improvement of host immune function, the use of adjuvant surgery, the development of new drug delivery systems for currently available drugs and the development of new classes of antifungal agents. Also, clinical trials to establish appropriate drug doses and duration of therapy are needed, as well as the benefits of antifungal prophylaxis explored and the use of combination therapies entertained. The war against drug resistant fungi has been identified as we approach the year 2000. With careful and cogent investigations, we do have the tools to fight back against these opportunists. Of all the strategies reviewed, however, in our opinion, the development of new antifungal drugs is likely to have the most significant future impact on our management of drug resistance in fungal infections.
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Ricin-cytotoxin conjugate administration reveals a physiologically relevant role for oxytocin in the control of gonadotropin secretion. Ann N Y Acad Sci 1992; 652:411-22. [PMID: 1626840 DOI: 10.1111/j.1749-6632.1992.tb34371.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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