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1.  Validity and Reliability of the European Heart Failure Self-care Behavior Scale Among Adults from the United States with Symptomatic Heart Failure 
Background
Heart failure (HF) self-care is an important component of disease management and the focus of many interventions.
Aim
The aim of this study was to evaluate the validity and reliability of the 9-item European HF Self-Care Behavior Scale (EHFScB-9) in a sample of 200 adults from the United States with symptomatic HF.
Methods
Psychometric tests included item and confirmatory factor analyses, convergent and discriminant validity, and internal consistency.
Results
Item-total correlations ranged from 0.25–0.65. Many fit indices for the EHFScB-9 and the 4-item consulting behaviors reached thresholds of acceptability. As expected, the EHFScB-9 was associated with other measures of HF self-care but not with quality-of-life. Coefficient α was 0.80 for the EHFScB-9 and and 0.85 for the consulting behaviors subscale.
Conclusion
The EHFScB-9 was a valid and reliable measure of HF self-care among English-speaking U.S. adults with symptomatic HF.
doi:10.1177/1474515112469316
PMCID: PMC4010092  PMID: 23263273
2.  Respiratory Function in Healthy Late Preterm Infants Delivered at 33-36 Weeks of Gestation 
The Journal of pediatrics  2012;162(3):464-469.
Objective
To compare pulmonary function testing including respiratory compliance (Crs) and time to peak tidal expiratory flow: expiratory time (Tptef:Te) at term corrected age in healthy infants born at 33-36 weeks of gestation versus healthy infants delivered at term.
Study design
We performed a prospective cohort study of late preterm infants born at 33-36 weeks without clinical respiratory disease (<12 hours of >0.21 FiO2) and studied at term corrected age. The comparison group was term infants matched for race and sex to the preterm infants and studied within 72 hours of delivery. Crs was measured with the single breath occlusion technique. A minimum of 50 flow-volume loops were collected to estimate Tptef:Te.
Results
Late preterm infants (n=31; mean gestational age 34.1 weeks, birth weight 2150 g) and 31 term infants were studied at term corrected age. The late preterm infants had decreased Crs (1.14 vs 1.32 mL/cm H2O/kg; p<0.02) and decreased Tptef:Te (0.308 vs 0.423; p<0.01) when compared with the term infants. Late preterm infants also had an increased respiratory resistance (0.064 vs 0.043 cm H2O/mL/sec; p<0.01).
Conclusions
Healthy late preterm infants (33-36 weeks of gestation) studied at term corrected age have altered pulmonary function when compared with healthy term infants.
doi:10.1016/j.jpeds.2012.09.042
PMCID: PMC3683449  PMID: 23140884
Expiratory flow ratio; late preterm infants; pulmonary function; respiratory compliance
3.  Oral Antimicrobial Use in Outpatient Cystic Fibrosis Pulmonary Exacerbation Management; a Single Center Experience 
Introduction
Cystic Fibrosis pulmonary disease is characterized by intermittent episodes of acute lung symptoms known as “pulmonary exacerbations”. While exacerbations are classically treated with parenteral antimicrobials, oral antibiotics are often used in “mild” cases.
Objectives
We determined how often management progressed to IV therapy. We also examined multiple courses of oral antimicrobials within one exacerbation and identified patient factors associated with unsuccessful treatment.
Methods
We performed a retrospective chart audit of oral antibiotic use in CF patients from March 2009 through March 2010, for “mild” CF exacerbations.
Results
Administration of a single versus multiple courses of oral antibiotics for treatment of “mild” CF exacerbation avoided progression to IV therapy 79.8% and 50.0% of the time, respectively. Overall, oral antibiotics circumvented the need for IV therapy 73.8% of the time. Using multi-variant analysis, we found multiple patient characteristics to be independent risk factors for oral antibiotic failure including a history of Pseudomonas infection (OR 2.13, CI 1.29 – 3.54), Cystic Fibrosis Related Diabetes (OR 1.85, CI 1.00 – 3.41), Allergic Bronchopulmonary Aspergillosis (OR 3.81, CI 1.38 – 10.56), low socioeconomic status (OR 1.67, CI 1.04 – 2.67), and calculated Baseline FEV1 < 75% of predicted prior to an acute exacerbation (OR 1.93, CI 1.20 – 3.08). Decline in FEV1 > 10%, weight for age, body mass index, distance from the CF center, and gender were not significant.
Conclusion
Our observations suggest that one course of oral antimicrobials is frequently effective in outpatient CF pulmonary exacerbations but exacerbations requiring more than one course of oral antibiotics are likely to require IV therapy.
doi:10.1111/j.1752-699X.2011.00246.x
PMCID: PMC3934104  PMID: 21595857
Cystic Fibrosis; exacerbation; antibiotics; pneumonia
4.  Simple Estimation of Hidden Correlation in Repeated Measures 
Statistics in medicine  2011;30(29):3403-3415.
In medical and social studies, it is often desirable to assess the correlation between characteristics of interest that are not directly observable. In such cases, repeated measures are often available, but the correlation between the repeated measures is not the same as that between the true characteristics that are confounded with the measurement errors. The latter is called the hidden correlation. Previously, the problem has been treated by assuming prior knowledge about the measurement errors, or by using relatively complex statistical models, such as the mixed effects models, with no closed-form expression for the estimated hidden correlation. We propose a simple estimator of the hidden correlation that is very much like the Pearson correlation coefficient, with a closed-form expression, under assumptions much weaker than the mixed effects model. Simulation results show that the proposed simple estimator performs similarly as the restricted maximum likelihood (REML) estimator in mixed models, but is computationally much more efficient than REML. Simulation comparison with the Pearson correlation is also made. A real data example is considered.
doi:10.1002/sim.4366
PMCID: PMC3891926  PMID: 21997471
Correlation Coefficient; Hypothesis Testing; Repeated Measures
5.  Unprofessional behavior 
doi:10.1177/1715163513516070
PMCID: PMC3908624  PMID: 24494008
6.  Human Neural Stem Cells Induce Functional Myelination in Mice with Severe Dysmyelination 
Science translational medicine  2012;4(155):10.1126/scitranslmed.3004371.
Shiverer-immunodeficient (Shi-id) mice demonstrate defective myelination in the central nervous system (CNS) and significant ataxia by 2 to 3 weeks of life. Expanded, banked human neural stem cells (HuCNS-SCs) were transplanted into three sites in the brains of neonatal or juvenile Shi-id mice, which were asymptomatic or showed advanced hypomyelination, respectively. In both groups of mice, HuCNS-SCs engrafted and underwent preferential differentiation into oligodendrocytes. These oligodendrocytes generated compact myelin with normalized nodal organization, ultrastructure, and axon conduction velocities. Myelination was equivalent in neonatal and juvenile mice by quantitative histopathology and high-field ex vivo magnetic resonance imaging, which, through fractional anisotropy, revealed CNS myelination 5 to 7 weeks after HuCNS-SC transplantation. Transplanted HuCNS-SCs generated functional myelin in the CNS, even in animals with severe symptomatic hypomyelination, suggesting that this strategy may be useful for treating dysmyelinating diseases.
doi:10.1126/scitranslmed.3004371
PMCID: PMC3864816  PMID: 23052293
7.  Hemodynamic and Metabolic Correlates of Perinatal White Matter Injury Severity 
PLoS ONE  2013;8(12):e82940.
Background and Purpose
Although the spectrum of perinatal white matter injury (WMI) in preterm infants is shifting from cystic encephalomalacia to milder forms of WMI, the factors that contribute to this changing spectrum are unclear. We hypothesized that the variability in WMI quantified by immunohistochemical markers of inflammation could be correlated with the severity of impaired blood oxygen, glucose and lactate.
Methods
We employed a preterm fetal sheep model of in utero moderate hypoxemia and global severe but not complete cerebral ischemia that reproduces the spectrum of human WMI.
Since there is small but measurable residual brain blood flow during occlusion, we sought to determine if the metabolic state of the residual arterial blood was associated with severity of WMI. Near the conclusion of hypoxia-ischemia, we recorded cephalic arterial blood pressure, blood oxygen, glucose and lactate levels. To define the spectrum of WMI, an ordinal WMI rating scale was compared against an unbiased quantitative image analysis protocol that provided continuous histo-pathological outcome measures for astrogliosis and microgliosis derived from the entire white matter.
Results
A spectrum of WMI was observed that ranged from diffuse non-necrotic lesions to more severe injury that comprised discrete foci of microscopic or macroscopic necrosis. Residual arterial pressure, oxygen content and blood glucose displayed a significant inverse association with WMI and lactate concentrations were directly related. Elevated glucose levels were the most significantly associated with less severe WMI.
Conclusions
Our results suggest that under conditions of hypoxemia and severe cephalic hypotension, WMI severity measured using unbiased immunohistochemical measurements correlated with several physiologic parameters, including glucose, which may be a useful marker of fetal response to hypoxia or provide protection against energy failure and more severe WMI.
doi:10.1371/journal.pone.0082940
PMCID: PMC3886849  PMID: 24416093
8.  Real-time prostate motion assessment: image-guidance and the temporal dependence of intra-fraction motion 
BMC Medical Physics  2013;13:4.
Background
The rapid adoption of image-guidance in prostate intensity-modulated radiotherapy (IMRT) results in longer treatment times, which may result in larger intrafraction motion, thereby negating the advantage of image-guidance. This study aims to qualify and quantify the contribution of image-guidance to the temporal dependence of intrafraction motion during prostate IMRT.
Methods
One-hundred and forty-three patients who underwent conventional IMRT (n=67) or intensity-modulated arc therapy (IMAT/RapidArc, n=76) for localized prostate cancer were evaluated. Intrafraction motion assessment was based on continuous RL (lateral), SI (longitudinal), and AP (vertical) positional detection of electromagnetic transponders at 10 Hz. Daily motion amplitudes were reported as session mean, median, and root-mean-square (RMS) displacements. Temporal effect was evaluated by categorizing treatment sessions into 4 different classes: IMRTc (transponder only localization), IMRTcc (transponder + CBCT localization), IMATc (transponder only localization), or IMATcc (transponder + CBCT localization).
Results
Mean/median session times were 4.15/3.99 min (IMATc), 12.74/12.19 min (IMATcc), 5.99/5.77 min (IMRTc), and 12.98/12.39 min (IMRTcc), with significant pair-wise difference (p<0.0001) between all category combinations except for IMRTcc vs. IMATcc (p>0.05). Median intrafraction motion difference between CBCT and non-CBCT categories strongly correlated with time for RMS (t-value=17.29; p<0.0001), SI (t-value=−4.25; p<0.0001), and AP (t-value=2.76; p<0.0066), with a weak correlation for RL (t-value=1.67; p=0.0971). Treatment time reduction with non-CBCT treatment categories showed reductions in the observed intrafraction motion: systematic error (Σ)<0.6 mm and random error (σ)<1.2 mm compared with ≤0.8 mm and <1.6 mm, respectively, for CBCT-involved treatment categories.
Conclusions
For treatment durations >4-6 minutes, and without any intrafraction motion mitigation protocol in place, patient repositioning is recommended, with at least the acquisition of the lateral component of an orthogonal image pair in the absence of volumetric imaging.
doi:10.1186/1756-6649-13-4
PMCID: PMC3849088  PMID: 24059584
Prostate cancer; Real-time motion tracking; Intrafraction variation; Treatment margin; Treatment time
9.  Healing Pathways: A Program for Women with Physical Disabilities and Depression 
Objective. The objective of this study was to test the efficacy of the Healing Pathways (HP) program in reducing clinically significantly depressive symptoms in women with physical disabilities (WPD). Healing Pathways is a peer-implemented group mental health treatment program targeting WPD who have clinically significant cooccurring depressive symptoms. Participants. Eighty women were randomized in this trial. Design. This study used a community-based participatory intervention research design. Using community-based recruiting methods, participants were recruited from Centers for Independent Living, local disability service organizations, via Craig's list as well as other community locations such as grocery stores and bus stops. Women participated in the HP program for 14 weeks. Results. The primary outcome variable for this study was reduction in depressive symptoms as measured by the Center for Epidemiologic Depression Scale (CES-D). We found that there was a significant interaction effect of treatment by time on depression scores, F(3,210) = 9.51, P < 0.0001, partial η2 = 0.101. Investigation of the predicted mean profile over time in the intervention group demonstrated that depression scores decreased greatly from baseline to the first posttest and remained stable in the two followups, whereas there was a little change in the mean profile over time in the control group. Conclusion. The HP program has demonstrated initial efficacy in reducing depressive symptoms in women with physical disabilities.
doi:10.1155/2013/649875
PMCID: PMC3659440  PMID: 23738072
10.  ARRESTED PRE-OLIGODENDROCYTE MATURATION CONTRIBUTES TO MYELINATION FAILURE IN PREMATURE INFANTS 
Annals of Neurology  2012;71(1):93-109.
Objective
The major form of MRI-defined white matter injury (WMI) comprises diffuse lesions where the burden of small necrotic foci (microscopic necrosis) is poorly defined. We hypothesized that myelination failure associated with diffuse WMI involves an aberrant injury response linked to arrested pre-oligodendrocyte (preOL) maturation in reactive astrocyte-rich lesions.
Methods
A retrospective autopsy series (1983–2000) was selected for cases with diffuse WMI and analyzed relative to prospectively-collected contemporary cases (2003–2010). Controls were age and region-matched to address regional variation in preOL maturation. Successive oligodendrocyte stages were analyzed with lineage-specific markers. Microscopic necrosis was quantified with microglial markers. Axon injury markers defined the burden of axonopathy. Extracellular matrix remodelling was defined by detection of hyaluronic acid (HA), an inhibitor of preOL maturation, and the HA receptor, CD44.
Results
In the contemporary case series, diffuse WMI was accompanied by a significant reduction in the burden of microscopic necrosis and axonopathy. Diffuse astrogliosis extended into the lesion surround with elevated HA and astrocyte-expressed CD44. The total population of OL lineage stages was significantly increased in lesions. This increase coincided with significant expansion of the preOL pool.
Interpretation
Although these data confirm that microscopic necrosis occurs in contemporary cases, the markedly decreased burden supports that it does not contribute substantially to myelination failure. The primary mechanism of myelination failure involves a disrupted cellular response whereby preOLs fail to differentiate in diffuse astrogliotic lesions. Pre-oligodendrocyte maturation arrest converts chronic WMI to a more immature state related to the burden of astrogliosis.
doi:10.1002/ana.22627
PMCID: PMC3270934  PMID: 22275256
11.  Apex to Base Left Ventricular Twist Mechanics Computed From High Frame Rate Two-Dimensional and Three-Dimensional Echocardiography: A Comparison Study 
Background
The aim of this study was to compare two-dimensional (2D) and three-dimensional (3D) methods for computing left ventricular (LV) rotation.
Methods
A two-axis linear/rotary system was designed using rotary motors controlled through a digital interface, and 10 freshly harvested pig hearts were studied. Each heart was mounted on the rotary actuator with the base being rotated at different known degrees of rotation (10°, 15°, 20°, and 25°) and was passively driven by a pump with calibrated stoke volume (50 mL) at a constant rate (60 beats/min) simultaneously. Cardiac motion was scanned to acquire 2D short-axis views using a GE Vivid 7 system for assessing rotation, and 3D apical full-volume loops were acquired using a Toshiba Applio Artida ultrasound system. Full-volume 3D image loops were analyzed online with Toshiba Wall Motion Tracking software, and short-axis 2D images were analyzed offline for LV rotation in GE EchoPAC PC at corresponding LV levels.
Results
At each state, both 2D and 3D echocardiography detected the changes in LV rotation but overestimated the rotation degrees. The biases for overestimation from 3D imaging were smaller compared with 2D imaging at each LV level. Both methods, when compared with each other, showed a linear correlation (r = 0.84, P < .0001). Bland-Altman comparison showed 99% of data points within range, with a constant bias between both methods (adjusted values of 3D = 1.892 + 0.964 × 3D).
Conclusions
Although 3D echocardiography showed smaller bias, the results between 2D and 3D echocardiography were comparable.
doi:10.1016/j.echo.2011.09.001
PMCID: PMC3321829  PMID: 21995883
LV twist; Validation study; 3D echocardiography
12.  Histopathological Correlates of MRI-Defined Chronic Perinatal White Matter Injury 
Annals of neurology  2011;70(3):493-507.
Objective
Although MRI is the optimal imaging modality to define cerebral white-matter injury (WMI) in preterm survivors, the histopathological features of MRI-defined chronic lesions are poorly defined. We hypothesized that chronic WMI is related to a combination of delayed oligodendrocyte (OL) lineage cell death and arrested maturation of pre-oligodendrocytes (preOLs). We determined whether ex vivo MRI can distinguish distinct microglial and astroglial responses related to WMI progression and arrested preOL differentiation.
Methods
We employed a preterm fetal sheep model of global cerebral ischemia where acute WMI results in selective preOL degeneration. We developed novel algorithms to register histopathologically defined lesions with contrast- and diffusion-weighted high-field ex vivo MRI data.
Results
Despite mild delayed preOL degeneration, preOL density recovered to control levels by 7 days after ischemia and was ~2 fold greater at 14 days. However, pre-myelinating OLs were significantly diminished at 7 and 14 days. WMI evolved to mostly gliotic lesions where arrested preOL differentiation was directly proportional to the magnitude of astrogliosis. A reduction in cerebral WM volume was accompanied by four classes of MRI-defined lesions. Each lesion type displayed unique astroglial and microglial responses that corresponded to distinct forms of necrotic or non-necrotic injury. High-field MRI defined two novel hypo-intense signal abnormalities on T2-weighted images that coincided with microscopic necrosis or identified astrogliosis with high sensitivity and specificity.
Interpretation
These studies support the potential of high-field MRI for early identification of microscopic necrosis and gliosis with preOL maturation arrest, a common form of WMI in preterm survivors.
doi:10.1002/ana.22501
PMCID: PMC3170499  PMID: 21796666
13.  Missed opportunity 
doi:10.3821/145.2.cpj51
PMCID: PMC3567543  PMID: 23509490
14.  Distinct Cytokine Patterns Identified from Multiplex Profiles of Murine DSS and TNBS-Induced Colitis 
Inflammatory bowel diseases  2009;15(3):341-352.
The cytokine network in inflammatory bowel disease (IBD) is a complex, dynamic system that plays an important role in regulating mucosal innate and adaptive immune responses. While several studies have been done to evaluate immunomodulatory profiles in murine IBD, they have been limited to a relatively small number of cytokines that do not take into account its dependency of the interplay of multiple factors, and therefore the diagnostic potential of their cytokine profiles have been inconclusive. Herein we demonstrate a novel approach of comprehensive serum multiplex cytokine profiling to describe the modulation of 16 Th1, Th2, Th17 cytokines and chemokines in both acute and chronic murine models of DSS and TNBS-induced colitis. Distinctive disease-specific cytokine profiles were identified with significant correlations to disease activity and duration of disease. TNBS colitis exhibits heightened Th1-Th17 response (increased IL-12 and IL-17) as the disease becomes chronic. In contrast, DSS colitis switches from a Th1-Th17-mediated acute inflammation (increased TNFα, IL6, IL-17 and KC) to a predominant Th2-mediated inflammatory response (increase in IL-4 and IL-10 and concomitant decrease in TNFα, IL6, IL-17 and KC) in the chronic state. Profiles of multiple cytokines seen systemically were also validated locally in colonic mucosa. Moreover, advanced multivariate analyses identified discriminatory cytokine profiles that can be sufficiently used to distinguish unaffected controls from diseases, and one disease type from another. IL-6 and IL-12 stratified gender-associated disease activity in chronic colitis. Our studies provide insight into disease immunopathogenesis and illustrate the significant potential of utilizing multiplex cytokine profiles and bioinformatics as diagnostic tools in IBD.
doi:10.1002/ibd.20753
PMCID: PMC2643312  PMID: 18942757
Cytokines; Multiplex ELISA; DSS Colitis; TNBS Colitis; Inflammatory Bowel Disease
15.  Meta-analysis and Imputation Identifies a 109 kb Risk Haplotype Spanning TNFAIP3 Associated with Lupus Nephritis and Hematologic Manifestations 
Genes and immunity  2009;10(5):470-477.
TNFAIP3 encodes the ubiquitin modifying enzyme, A20, a key regulator of inflammatory signaling pathways. We previously reported association between TNFAIP3 variants and systemic lupus erythematosus (SLE). In order to further localize the risk variant(s), we performed a meta-analysis using genetic data available from two Caucasian case/control datasets (1453 total cases, 3381 total controls) and 713 SLE trio families. The best result was found at rs5029939 (P = 1.67 × 10−14, OR = 2.09, 95% CI 1.68–2.60). We then imputed SNPs from the CEU Phase II HapMap using genotypes from 431 SLE cases and 2155 controls. Imputation identified eleven SNPs in addition to three observed SNPs, which together, defined a 109 kb SLE risk segment surrounding TNFAIP3. When evaluating whether the rs5029939 risk allele was associated with SLE clinical manifestations, we observed that heterozygous carriers of the TNFAIP3 risk allele at rs5029939 have a two-fold increased risk of developing renal or hematologic manifestations compared to homozygous non-risk subjects. In summary, our study strengthens the genetic evidence that variants in the region of TNFAIP3 influence risk for SLE, particularly in patients with renal and hematologic manifestations, and narrows the risk effect to a 109 kb DNA segment that spans the TNFAIP3 gene.
doi:10.1038/gene.2009.31
PMCID: PMC2714405  PMID: 19387456
systemic lupus erythematosus; TNFAIP3; imputation; meta-analysis
16.  Protection from Endotoxic Shock by EVK-203, a Novel Alkylpolyamine Sequestrant of Lipopolysaccharide 
Bioorganic & medicinal chemistry  2007;15(17):5694-5709.
Lipopolysaccharides (LPS), play a key role in the pathogenesis of septic shock, a major cause of mortality in the critically ill patient. The only therapeutic option aimed at limiting downstream systemic inflammatory processes by targeting lipopolysaccharide is Toraymyxin™, an extracorporeal hemoperfusion device using solid phase-immobilized polymyxin B (PMB). While PMB is known to effectively sequester LPS, its severe systemic toxicity proscribes its parenteral use, and hemoperfusion may not be feasible in patients in shock. In our continuing efforts to develop small-molecule mimics which display the LPS-sequestering properties, but not the toxicity of PMB, a series of mono- and bis-substituted dialkylpolyamines were synthesized and evaluated. We show that EVK-203, analkylpolyamine compound specifically binds to, and neutralizes, the activity of LPS, and affords complete protection in a murine model of endotoxic shock. EVK-203 is without any apparent toxicity when administered to mice at multiples of therapeutic doses for several days. The specific endotoxinsequestering property along with a very favorable therapeutic index renders this compound an ideal candidate for preclinical development.
doi:10.1016/j.bmc.2007.06.015
PMCID: PMC2039869  PMID: 17583517
Endotoxin; Lipopolysaccharide; Sepsis; Septic Shock; Alkylpolyamine; Lipopolyamine
17.  Renal Cortical Deterioration in Children With Spinal Dysraphism: Analysis of Risk Factors 
The Journal of Spinal Cord Medicine  2007;30(Suppl 1):S30-S34.
Background/Objective:
Because hydronephrosis and reflux are reversible, we believe cortical loss represents true renal deterioration in children with spinal dysraphism. Our goal was to better define risk factors for cortical loss.
Methods:
After institutional review board approval, we reviewed the medical records of 272 children with spinal dysraphism. The following factors were evaluated: age, sex, renal and bladder imaging, urodynamic parameters, medications, catheterization program, continence, infections, and surgical history. Renal cortical loss was defined by scarring or a differential function greater than 15% using a nuclear scan. Univariate and multivariate logistic regression models were fitted to test the associations of specific variables with cortical loss.
Results:
Renal cortical loss was found in 41% of children with high-grade reflux vs 2% of children without reflux. Univariate analysis showed only high-grade reflux and female sex to be independent risk factors. Controlling for age and sex, reflux and initiation of catheterization after 1 year of age are significant risk factors. High bladder pressure and hydronephrosis in the absence of reflux were not associated with cortical loss. Multivariate analysis showed that girls with reflux have a 55-fold increased risk of cortical loss.
Conclusion:
By limiting the definition of renal deterioration to cortical loss, we identified relevant risk factors: reflux, female sex, and delayed initiation of clean intermittent catheterization. We have also discounted other suspected risk factors: hydronephrosis and elevated bladder pressure. Rather than continuing our focus on hydronephrosis and urodynamics, we believe more research and management debate should be afforded to females with reflux.
PMCID: PMC2031976  PMID: 17874684
Spinal dysraphism; Kidney; Vesicoureteral reflux; Bladder; Urodynamics; Hydronephrosis; Spina bifida; Catheterization; Outcomes research; Myelodysplasia
18.  Bound To Shock: Protection from Lethal Endotoxemic Shock by a Novel, Nontoxic, Alkylpolyamine Lipopolysaccharide Sequestrant▿  
Lipopolysaccharide (LPS), or endotoxin, a structural component of gram-negative bacterial outer membranes, plays a key role in the pathogenesis of septic shock, a syndrome of severe systemic inflammation which leads to multiple-system organ failure. Despite advances in antimicrobial chemotherapy, sepsis continues to be the commonest cause of death in the critically ill patient. This is attributable to the lack of therapeutic options that aim at limiting the exposure to the toxin and the prevention of subsequent downstream inflammatory processes. Polymyxin B (PMB), a peptide antibiotic, is a prototype small molecule that binds and neutralizes LPS toxicity. However, the antibiotic is too toxic for systemic use as an LPS sequestrant. Based on a nuclear magnetic resonance-derived model of polymyxin B-LPS complex, we had earlier identified the pharmacophore necessary for optimal recognition and neutralization of the toxin. Iterative cycles of pharmacophore-based ligand design and evaluation have yielded a synthetically easily accessible N1,mono-alkyl-mono-homologated spermine derivative, DS-96. We have found that DS-96 binds LPS and neutralizes its toxicity with a potency indistinguishable from that of PMB in a wide range of in vitro assays, affords complete protection in a murine model of LPS-induced lethality, and is apparently nontoxic in vertebrate animal models.
doi:10.1128/AAC.00200-07
PMCID: PMC1932507  PMID: 17548488
19.  Structural Correlation Between Lipophilicity and Lipopolysaccharide-sequestering activity in Spermine-Sulfonamide Analogs 
Lipopolysaccharides (LPS), otherwise termed ‘endotoxins’, are outer-membrane constituents of Gram-negative bacteria, and play a key role in the pathogenesis of ‘Septic Shock’, a major cause of mortality in the critically ill patient. We had previously defined the pharmacophore necessary for small molecules to specifically bind and neutralize this complex carbohydrate. A series of aryl and aliphatic spermine-sulfonamide analogs were synthesized and tested in a series of binding and cell-based assays in order to probe the effect of lipophilicity on sequestration ability. A strong correlation was indeed found, supporting the hypothesis that endotoxin-neutralizing ability involves a lipophilic or membrane attachment event. The research discussed herein may be useful for the design of additional carbohydrate recognizing molecules and endotoxin-neutralizing drugs.
doi:10.1016/j.bmcl.2006.09.026
PMCID: PMC1991285  PMID: 17010608
20.  Structural Correlates of Antibacterial and Membrane-Permeabilizing Activities in Acylpolyamines 
A homologous series of mono- and bis-acyl polyamines with varying acyl chain lengths originally synthesized for the purpose of sequestering lipopolysaccharide were evaluated for antimicrobial activity to test the hypothesis that these bis-cationic amphipathic compounds may also bind to and permeabilize intact gram-negative bacterial membranes. Some compounds were found to possess significant antimicrobial activity, mediated via permeabilization of bacterial membranes. Structure-activity relationship studies revealed a strong dependence of the acyl chain length on antimicrobial potency and permeabilization activity. Homologated spermine, bis-acylated with C8 or C9 chains, was found to profoundly sensitize Escherichia coli to hydrophobic antibiotics such as rifampin. Nonspecific cytotoxicity is a potential drawback of these membranophilic compounds. However, the surface activity of these cationic amphipaths is strongly attenuated under physiological conditions via binding to serum albumin. Significant antibacterial activity is still retained in the presence of physiological concentrations of human serum albumin, suggesting that these compounds may serve as leads in the development of novel adjuncts to conventional antimicrobial chemotherapy.
doi:10.1128/AAC.50.3.852-861.2006
PMCID: PMC1426419  PMID: 16495242
21.  Science and journalism: Never the two shall meet? 
doi:10.1503/cmaj.1060006
PMCID: PMC1421465  PMID: 16606965

Results 1-21 (21)