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1.
Soft Matter ; 20(4): 887-899, 2024 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-38175527

RESUMEN

The formation of pairs of particles or cells of different types in microfluidic channels can be desired or detrimental in healthcare applications. It is still unclear what role softness heterogeneity plays in the formation of these particle pairs. We use an in-house lattice-Boltzmann-immersed-boundary-finite-element solver to simulate a pair of particles with different softness flowing through a straight channel with a rectangular cross-section under initial conditions representative of a dilute suspension. We find that softness heterogeneity significantly affects the pair dynamics, determining whether a pair will form or not, and determining the lateral and inter-particle equilibrium behaviour in the pair. We also observe close matches between the transient deformation of particles in a linear pair and single particles in isolation. These results further our understanding of pair behaviour, providing a foundation for understanding particle train formation, and open up the potential to develop reduced-order models for particle pair formation based upon the behaviour of single particles.

2.
Brain Behav Immun ; 107: 165-178, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36243287

RESUMEN

Sepsis and systemic inflammation are often accompanied by severe encephalopathy, sleep disruption and delirium that strongly correlate with poor clinical outcomes including long-term cognitive deficits. The cardinal manifestations of delirium are fluctuating altered mental status and inattention, identified in critically ill patients by interactive bedside assessment. The lack of analogous assessments in mouse models or clear biomarkers is a challenge to preclinical studies of delirium. In this study, we utilized concurrent measures of telemetric EEG recordings and neurobehavioral tasks in mice to characterize inattention and persistent cognitive deficits following polymicrobial sepsis. During the 24-hour critical illness period for the mice, slow-wave EEG dominance, sleep disruption, and hypersensitivity to auditory stimuli in neurobehavioral tasks resembled clinical observations in delirious patients in which alterations in similar outcome measurements, although measured differently in mice and humans, are reported. Mice were tested for nest building ability 7 days after sepsis induction, when sickness behaviors and spontaneous activity had returned to baseline. Animals that showed persistent deficits determined by poor nest building at 7 days also exhibited molecular changes in hippocampal long-term potentiation compared to mice that returned to baseline cognitive performance. Together, these behavioral and electrophysiological biomarkers offer a robust mouse model with which to further probe molecular pathways underlying brain and behavioral changes during and after acute illness such as sepsis.


Asunto(s)
Potenciación a Largo Plazo , Humanos , Ratones , Animales
3.
J Org Chem ; 88(14): 9730-9736, 2023 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-37436366

RESUMEN

Bismacycles featuring a sulfone-bridged scaffold have recently been developed as versatile and convenient electrophilic arylating agents. Here, we report that the exocyclic aryl group, which is ultimately transferred to a nucleophilic coupling partner, can be functionalized through cross-coupling, heteroatom substitutions, oxidations and reductions, and protecting group manipulations. This "postsynthetic modification" approach provides concise and divergent access to complex aryl bismacycles. The utility of the functionalized bismacycles in electrophilic arylation of C-H and O-H bonds is demonstrated.

4.
Org Biomol Chem ; 21(41): 8294-8300, 2023 10 25.
Artículo en Inglés | MEDLINE | ID: mdl-37740307

RESUMEN

Lipoxins are an important class of pro-resolving mediators that play a crucial role in the resolution of inflammation. Thus, the synthesis of more chemically and metabolically stable synthetic lipoxin analogues is an area of significant interest. Whereas synthetic analogues of lipoxin A4 (LXA4) have been well studied, analogues of lipoxin B4 (LXB4) have been the focus of considerably less attention. Herein we report the asymmetric synthesis of a focused library of LXB4 mimetics in which the triene core of the molecule has been replaced with different aromatic and heteroaromatic rings. The synthesis of each of these analogues was achieved by a general strategy in which the key steps were a Suzuki cross coupling between a common upper chain fragment and an aromatic lower chain, followed by a stereoselective ketone reduction.


Asunto(s)
Lipoxinas , Humanos , Lipoxinas/química , Inflamación
5.
Hippocampus ; 32(11-12): 797-807, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-36063105

RESUMEN

Understanding the role of dentate gyrus (DG) mossy cells (MCs) in learning and memory has rapidly evolved due to increasingly precise methods for targeting MCs and for in vivo recording and activity manipulation in rodents. These studies have shown MCs are highly active in vivo, strongly remap to contextual manipulation, and that their inhibition or hyperactivation impairs pattern separation and location or context discrimination. Less well understood is how MC activity is modulated by neurohormonal mechanisms, which might differentially control the participation of MCs in cognitive functions during discrete states, such as hunger or satiety. In this study, we demonstrate that glucagon-like peptide-1 (GLP-1), a neuropeptide produced in the gut and the brain that regulates food consumption and hippocampal-dependent mnemonic function, might regulate MC function through expression of its receptor, GLP-1R. RNA-seq demonstrated that most, though not all, Glp1r in hippocampal principal neurons is expressed in MCs, and in situ hybridization revealed strong expression of Glp1r in hilar neurons. Glp1r-ires-Cre mice crossed with Ai14D reporter mice followed by co-labeling for the MC marker GluR2/3 revealed that almost all MCs in the ventral DG expressed Glp1r and that almost all Glp1r-expressing hilar neurons were MCs. However, only ~60% of dorsal DG MCs expressed Glp1r, and Glp1r was also expressed in small hilar neurons that were not MCs. Consistent with this expression pattern, peripheral administration of the GLP-1R agonist exendin-4 (5 µg/kg) increased cFos expression in ventral but not dorsal DG hilar neurons. Finally, whole-cell patch-clamp recordings from ventral MCs showed that bath application of exendin-4 (200 nM) depolarized MCs and increased action potential firing. Taken together, this study adds to known MC activity modulators a neurohormonal mechanism that may preferentially affect ventral DG physiology and may potentially be targetable by several GLP-1R pharmacotherapies already in clinical use.


Asunto(s)
Receptor del Péptido 1 Similar al Glucagón , Fibras Musgosas del Hipocampo , Animales , Ratones , Receptor del Péptido 1 Similar al Glucagón/genética , Receptor del Péptido 1 Similar al Glucagón/metabolismo , Exenatida/farmacología , Exenatida/metabolismo , Fibras Musgosas del Hipocampo/fisiología , Péptido 1 Similar al Glucagón/metabolismo , Hipocampo/metabolismo , Giro Dentado/metabolismo
6.
J Am Chem Soc ; 143(26): 9729-9736, 2021 07 07.
Artículo en Inglés | MEDLINE | ID: mdl-34161076

RESUMEN

Bicyclo[1.1.1]pentylamines (BCPAs) are of growing importance to the pharmaceutical industry as sp3-rich bioisosteres of anilines and N-tert-butyl groups. Here we report a facile synthesis of 1,3-disubstituted BCPAs using a twofold radical functionalization strategy. Sulfonamidyl radicals, generated through fragmentation of α-iodoaziridines, undergo initial addition to [1.1.1]propellane to afford iodo-BCPAs; the newly formed C-I bond in these products is then functionalized via a silyl-mediated Giese reaction. This chemistry also translates smoothly to 1,3-disubstituted iodo-BCPs. A wide variety of radical acceptors and iodo-BCPAs are accommodated, providing straightforward access to an array of valuable aniline-like isosteres.

7.
Neurobiol Dis ; 154: 105343, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-33753293

RESUMEN

This study examines changes in synaptic transmission with progression of the chronic epileptic state. Male Sprague-Dawley rats (P40-45) were injected with either saline or pilocarpine. In rats injected with pilocarpine, status epilepticus ensued. Hippocampal slices were cut 20-60 days or 80-110 days post-treatment. Evoked and miniature EPSCs (mEPSCs) were recorded from CA1 pyramidal neurons using whole-cell voltage-clamp. Fiber volleys were also recorded from stratum radiatum. Evoked EPSCs from the pilocarpine-treated cohort showed enhanced amplitudes 20-60 days post-treatment compared to the saline-treated cohort, whereas mEPSCs recorded from the same age group showed no change in event frequency and a slight but significant decrease in mEPSC amplitude distribution. In contrast, comparing evoked EPSCs and mEPSCs recorded 80-110 days after treatment indicated reduced amplitudes from pilocarpine-treated animals compared to controls. mEPSC inter-event interval decreased. This could be explained by a partial depletion of the ready releasable pool of neurotransmitter vesicles in Schaffer collateral presynaptic terminals of the pilocarpine-treated rats. In both saline- and pilocarpine-treated cohorts, concomitant decreases in mEPSC amplitudes as time after treatment progressed suggest that age-related changes in CA1 circuitry may be partially responsible for changes in synaptic transmission that may influence the chronic epileptic state.


Asunto(s)
Región CA1 Hipocampal/fisiopatología , Progresión de la Enfermedad , Epilepsia/fisiopatología , Potenciales Postsinápticos Excitadores/fisiología , Estado Epiléptico/fisiopatología , Transmisión Sináptica/fisiología , Animales , Región CA1 Hipocampal/efectos de los fármacos , Enfermedad Crónica , Epilepsia/inducido químicamente , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Masculino , Agonistas Muscarínicos/toxicidad , Pilocarpina/toxicidad , Ratas , Ratas Sprague-Dawley , Estado Epiléptico/inducido químicamente , Transmisión Sináptica/efectos de los fármacos
8.
Exp Brain Res ; 239(10): 3045-3057, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34363514

RESUMEN

Previously, we reported that distal Schaffer collaterals undergo biphasic changes in excitability during high-frequency stimulation (HFS), with an early hyper-excitability period followed by an excitability depression period. The extracellular divalent cations calcium and magnesium can regulate membrane excitability in neuronal tissue. Therefore, we hypothesized that altering the concentrations of extracellular calcium and magnesium would alter the biphasic excitability changes. We tested this hypothesis by recording distal Schaffer collateral fiber volleys in stratum radiatum of hippocampal area CA1 during 100 Hz HFS in artificial cerebral spinal fluid (ACSF) containing normal and altered concentrations of extracellular divalent cations. Our normal ACSF contained 2.0 mM calcium and 2.0 mM magnesium. We examined four solutions with altered divalent cation concentrations: (1) high-calcium/low-magnesium (3.8 mM/0.2 mM), (2) low-calcium/high-magnesium (0.2 mM/3.8 mM), (3) high-calcium/normal-magnesium (3.8 mM/2.0 mM), or (4) normal-calcium/high-magnesium (2.0 mM/10.0 mM), and assessed the effects on Schaffer collateral responses. Increasing or decreasing extracellular calcium enhanced or reduced (respectively) the early hyper-excitable period whereas increasing extracellular magnesium reduced the later excitability depression. Because these results might be explained by altered calcium influx through voltage-gated calcium (CaV) channels, we tested CaV blockers (ω-agatoxin IVA, ω-conotoxin-GVIA, cadmium), but observed no effects on responses during HFS. Some of the effects of altered divalent cation concentration may be explained by altered membrane surface charge. Although this mechanism does not completely explain our findings, calcium influx through CaV channels is not required.


Asunto(s)
Hipocampo , Neuronas , Axones , Calcio , Cationes Bivalentes , Humanos , omega-Conotoxina GVIA
9.
J Neurophysiol ; 113(10): 3646-62, 2015 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-25855695

RESUMEN

Axon conduction fidelity is important for signal transmission and has been studied in various axons, including the Schaffer collateral axons of the hippocampus. Previously, we reported that high-frequency stimulation (HFS) depresses Schaffer collateral excitability when assessed by whole-cell recordings from CA3 pyramidal cells but induces biphasic excitability changes (increase followed by decrease) in extracellular recordings of CA1 fiber volleys. Here, we examined responses from proximal (whole-cell or field-potential recordings from CA3 pyramidal cell somata) and distal (field-potential recordings from CA1 stratum radiatum) portions of the Schaffer collaterals during HFS and burst stimulation in hippocampal slices. Whole-cell and dual-field-potential recordings using 10-100-Hz HFS revealed frequency-dependent changes like those previously described, with higher frequencies producing more drastic changes. Dual-field-potential recordings revealed substantial differences in the response to HFS between proximal and distal regions of the Schaffer collaterals, with proximal axons depressing more strongly and only distal axons showing an initial excitability increase. Because CA3 pyramidal neurons normally fire in short bursts rather than long high-frequency trains, we repeated the dual recordings using 100-1,000-ms interval burst stimulation. Burst stimulation produced changes similar to those during HFS, with shorter intervals causing more drastic changes and substantial differences observed between proximal and distal axons. We suggest that functional differences between proximal and distal Schaffer collaterals may allow selective filtering of nonphysiological activity while maximizing successful conduction of physiological activity throughout an extensive axonal arbor.


Asunto(s)
Potenciales de Acción/fisiología , Fenómenos Biofísicos/fisiología , Hipocampo/citología , Fibras Nerviosas/fisiología , Red Nerviosa/fisiología , Neuronas/fisiología , Animales , Bicuculina/análogos & derivados , Bicuculina/farmacología , Maleato de Dizocilpina/farmacología , Estimulación Eléctrica , Antagonistas de Aminoácidos Excitadores/farmacología , Femenino , Antagonistas de Receptores de GABA-A/farmacología , Técnicas In Vitro , Fibras Nerviosas/efectos de los fármacos , Red Nerviosa/efectos de los fármacos , Neuronas/efectos de los fármacos , Técnicas de Placa-Clamp , Ácidos Fosfínicos/farmacología , Propanolaminas/farmacología , Quinoxalinas/farmacología , Ratas , Ratas Sprague-Dawley , Tiempo de Reacción/efectos de los fármacos
10.
Phys Rev Lett ; 114(13): 132002, 2015 Apr 03.
Artículo en Inglés | MEDLINE | ID: mdl-25884122

RESUMEN

For almost 50 years the structure of the Λ(1405) resonance has been a mystery. Even though it contains a heavy strange quark and has odd parity, its mass is lower than any other excited spin-1/2 baryon. Dalitz and co-workers speculated that it might be a molecular state of an antikaon bound to a nucleon. However, a standard quark-model structure is also admissible. Although the intervening years have seen considerable effort, there has been no convincing resolution. Here we present a new lattice QCD simulation showing that the strange magnetic form factor of the Λ(1405) vanishes, signaling the formation of an antikaon-nucleon molecule. Together with a Hamiltonian effective-field-theory model analysis of the lattice QCD energy levels, this strongly suggests that the structure is dominated by a bound antikaon-nucleon component. This result clarifies that not all states occurring in nature can be described within a simple quark model framework and points to the existence of exotic molecular meson-nucleon bound states.

11.
Surg Endosc ; 28(5): 1686-90, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24414455

RESUMEN

BACKGROUND: Conventional laparoscopic fundoplications (CLF) have been the gold standard for Nissen fundoplications (NFs) for two decades. The advent of a robotic approach for fundoplication procedures creates a potential alternative. Thus, we used a national database to examine perioperative outcomes with respect to open, laparoscopic, and robotic approaches. METHODS: The University Health System Consortium is an alliance of medical centers, numbering over 115 academic institutions and their 271 affiliated hospitals. We used International Classification of Diseases codes to elicit patients over the age of 18 years who received NF procedures. RESULTS: A total of 12,079 patients of similar demographic background received fundoplication procedures from October 2008 to June 2012. Of those, 2,168 were open fundoplications (OF), 9,572 were CLF, and 339 were robot-assisted laparoscopic fundoplications (RLF). CLF and RLF displayed no significance in mortality (0.1 vs. 0 %; p = 0.5489), morbidity (4.0 vs. 5.6 %; p = 0.1744), length of stay (2.8 ± 3.6 vs. 3.0 ± 3.5; p = 0.3242), and intensive care unit (ICU) cases (8.4 vs. 11.5 %; p = 0.051). However, CLF remained superior, with a lower 30-day re-admission rate (1.8 vs. 3.6 %; p < 0.05) and cost (US$7,968 ± 6,969 vs. US$10,644 ± 6,041; p < 0.05). When RLF was compared with OF, RLF had significantly improved morbidity (5.6 vs. 11 %; p < 0.05), length of stay (6.1 ± 7.2 vs. 3.0 ± 3.5 days; p < 0.05), less ICU admission (11.5 vs. 23.1 %; p <0.05) and less cost (US$10,644 ± 6,041 vs. US$12,766 ± 13,982; p < 0.05). CONCLUSIONS: Current data suggests that robot-assisted NF procedures have similar patient outcomes to conventional laparoscopic NF, with the exception of added cost and higher re-admission rate. While the higher costs are expected given the new technology, increasing re-admission rates are concerning and may represent the level of experience of the surgeon as well as the robotic learning curve.


Asunto(s)
Fundoplicación/economía , Reflujo Gastroesofágico/cirugía , Costos de la Atención en Salud/estadística & datos numéricos , Laparoscopía/economía , Laparotomía/economía , Robótica/economía , Adolescente , Anciano , Costos y Análisis de Costo , Bases de Datos Factuales , Femenino , Fundoplicación/métodos , Reflujo Gastroesofágico/economía , Humanos , Laparoscopía/métodos , Laparotomía/métodos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Robótica/métodos , Estados Unidos , Adulto Joven
12.
Res Sq ; 2024 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-38947034

RESUMEN

Objective and design: Here, we evaluated whether a synthetic lipoxin mimetic, designated AT-01-KG, would improve the course of influenza A infection in a murine model. Treatment: Mice were infected with influenza A/H1N1 and treated with AT-01-KG (1.7 mg/kg/day, i.p.) at day 3 post-infection. Methods: Mortality rate was assessed up to day 21 and inflammatory parameters were assessed at days 5 and 7. Results: AT-01-KG attenuated mortality, reducing leukocyte infiltration and lung damage at day 5 and day 7 post-infection. AT-01-KG is a Formyl Peptide Receptor 2 (designated FPR2/3 in mice) agonist, and the protective responses were not observed in FPR2/3 -/- animals. In mice treated with LXA4 (50mg/kg/day, i.p., days 3-6 post-infection), at day 7, macrophage reprogramming was observed, as seen by a decrease in classically activated macrophages and an increase in alternatively activated macrophages in the lungs. Furthermore, the number of apoptotic cells and cells undergoing efferocytosis was increased in the lavage of treated mice. Treatment also modulated the adaptive immune response, increasing the number of anti-inflammatory T cells (Th2) and regulatory T (Tregs) cells in the lungs of the treated mice. Conclusions: Therefore, treatment with a lipoxin A4 analog was beneficial in a model of influenza A infection in mice. The drug decreased inflammation and promoted resolution and beneficial immune responses, suggesting it may be useful in patients with severe influenza.

13.
Anal Chem ; 85(23): 11284-90, 2013 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-24171553

RESUMEN

A novel differentially pumped dual linear quadrupole ion trap (DLQIT) mass spectrometer was designed and built to facilitate tandem MS experiments free from interfering reactions. The instrument consists of two differentially pumped Thermo Scientific linear quadrupole ion trap (LQIT) systems that have been connected via an ion transfer octupole encased in a machined manifold. Tandem MS experiments can be performed in the front trap and then the resulting product ions can be transferred via axial ejection into the back trap for further, independent tandem MS experiments in a differentially pumped area. This approach allows the examination of consecutive collision-activated dissociation (CAD) and ion-molecule reactions without unwanted side reactions that often occur when CAD and ion-molecule reactions are examined in the same space. Hence, it greatly facilitates investigations of ion structures. In addition, the overall lower pressure of the DLQIT, as compared to commercial LQIT instruments, results in a reduction of unwanted side reactions with atmospheric contaminants, such as water and oxygen, in CAD and ion-molecule experiments.


Asunto(s)
Aceleradores de Partículas , Espectrometría de Masas en Tándem/métodos , Intercambio Iónico , Espectrometría de Masas/métodos
14.
Dermatitis ; 34(6): 532-535, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37819753

RESUMEN

Background: Identification of athletic shoes for patients with contact allergy is difficult. Company reports of allergen content are often incorrect. Objectives: To determine whether chemical analysis of 4 athletic shoes, previously reported to be free of the most common contact allergens, contain quantifiable allergen levels. Methods: Samples from the uppers and insoles of 4 shoes believed to be free of common allergens were assessed by mass spectrometry. A total of 4 rubber accelerators and 2 adhesives were directly quantified and additional 7 rubber accelerators were assessed using semiquantitative measures. Results: Aside from carbamates (assayed as 59 ppm zinc in insoles) in SeaVee's Sixty-Six sneakers, para-tertiarybutylphenol formaldehyde resin (PTBFR) (assayed as 7.6 ppm paratertiary butylphenol or 4-tertiary butylphenol [4TBP] in uppers) in Allbirds Tree Runners and rosin (assayed as 628 ppm sodium abietate in uppers) and carbamates (24 ppm zinc in uppers) in Saucony Jazz sneakers, these shoes had low levels of all allergens assayed in this study. Tom's Carlo sneakers contained rosin (127 ppm sodium abietate in insoles), PTBFR (6.5 ppm 4TBP in uppers), and carbamates (112 ppm sodium abietate in insoles) but had low levels of all other assayed allergens. Conclusions: Although identifying allergen-free shoes is challenging, the results of this analysis will help patch testing physicians recommend athletic shoes to patients with specific allergies.


Asunto(s)
Dermatitis Alérgica por Contacto , Deportes , Humanos , Alérgenos/efectos adversos , Alérgenos/análisis , Zapatos , Goma , Cromatografía de Gases y Espectrometría de Masas , Dermatitis Alérgica por Contacto/diagnóstico , Dermatitis Alérgica por Contacto/etiología , Carbamatos , Pruebas del Parche/métodos , Espectrometría de Masas , Sodio , Zinc
15.
Microsyst Nanoeng ; 9: 100, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37519826

RESUMEN

The study of flow and particle dynamics in microfluidic cross-slot channels is of high relevance for lab-on-a-chip applications. In this work, we investigate the dynamics of a rigid spherical particle in a cross-slot junction for a channel height-to-width ratio of 0.6 and at a Reynolds number of 120 for which a steady vortex exists in the junction area. Using an in-house immersed-boundary-lattice-Boltzmann code, we analyse the effect of the entry position of the particle in the junction and the particle size on the dynamics and trajectory shape of the particle. We find that the dynamics of the particle depend strongly on its lateral entry position in the junction and weakly on its vertical entry position; particles that enter close to the centre show trajectory oscillations. Larger particles have longer residence times in the junction and tend to oscillate less due to their confinement. Our work contributes to the understanding of particle dynamics in intersecting flows and enables the design of optimised geometries for cytometry and particle manipulation.

16.
Microbiol Spectr ; : e0051723, 2023 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-36975811

RESUMEN

Colonization with nontoxigenic Clostridioides difficile strain M3 (NTCD-M3) has been demonstrated in susceptible hamsters and humans when administered after vancomycin treatment. NTCD-M3 has also been shown to decrease risk of recurrent C. difficile infection (CDI) in patients following vancomycin treatment for CDI. As there are no data for NTCD-M3 colonization after fidaxomicin treatment, we studied the efficacy of NTCD-M3 colonization and determined fecal antibiotic levels in a well-studied hamster model of CDI. Ten of 10 hamsters became colonized with NTCD-M3 after 5 days of treatment with fidaxomicin when NTCD-M3 was administered daily for 7 days after treatment discontinuation. The findings were nearly identical to 10 vancomycin-treated hamsters also given NTCD-M3. High fecal levels of OP-1118, the major fidaxomicin metabolite, and vancomycin were noted during treatment with the respective agents and modest levels noted 3 days after treatment discontinuation at the time when most of the hamsters became colonized. These findings support the ongoing development of NTCD-M3 for the prevention of recurrent CDI. IMPORTANCE NTCD-M3 is a novel live biotherapeutic, that has been shown in a Phase 2 clinical trial to prevent recurrence of C. difficile infection (CDI) when administered shortly after antibiotic treatment of the initial CDI episode. Fidaxomicin was not, however, in widespread use at the time this study was conducted. A large multi-center Phase 3 clinical trial is now currently in the planning stage, and it is anticipated that many patients eligible for this study will be treated with fidaxomicin. Since efficacy in the hamster model of CDI has predicted success in patients with CDI, we studied the ability of NTCD-M3 to colonize hamsters after treatment with either fidaxomicin or vancomycin.

17.
J Neurophysiol ; 108(7): 1965-76, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22773781

RESUMEN

Long-term potentiation (LTP) is often induced experimentally by continuous high-frequency afferent stimulation (HFS), typically at 100 Hz for 1 s. Induction of LTP requires postsynaptic depolarization and voltage-dependent calcium influx. Induction is more effective if the same number of stimuli are given as a series of short bursts rather than as continuous HFS, in part because excitatory postsynaptic potentials (EPSPs) become strongly depressed during HFS, reducing postsynaptic depolarization. In this study, we examined mechanisms of EPSP depression during HFS in area CA1 of rat hippocampal brain slices. We tested for presynaptic terminal vesicle depletion by examining minimal stimulation-evoked excitatory postsynaptic currents (EPSCs) during 100-Hz HFS. While transmission failures increased, consistent with vesicle depletion, EPSC latencies also increased during HFS, suggesting a decrease in afferent excitability. Extracellular recordings of Schaffer collateral fiber volleys confirmed a decrease in afferent excitability, with decreased fiber volley amplitudes and increased latencies during HFS. To determine the mechanism responsible for fiber volley changes, we recorded antidromic action potentials in single CA3 pyramidal neurons evoked by stimulating Schaffer collateral axons. During HFS, individual action potentials decreased in amplitude and increased in latency, and these changes were accompanied by a large increase in the probability of action potential failure. Time derivative and phase-plane analyses indicated decreases in both axon initial segment and somato-dendritic components of CA3 neuron action potentials. Our results indicate that decreased presynaptic axon excitability contributes to depression of excitatory synaptic transmission during HFS at synapses between Schaffer collaterals and CA1 pyramidal neurons.


Asunto(s)
Vías Aferentes/fisiología , Región CA1 Hipocampal/fisiología , Potenciales Postsinápticos Excitadores , Depresión Sináptica a Largo Plazo/fisiología , Potenciales de Acción , Animales , Región CA3 Hipocampal/fisiología , Calcio/metabolismo , Estimulación Eléctrica , Masculino , Células Piramidales/fisiología , Ratas , Ratas Sprague-Dawley , Vesículas Sinápticas/metabolismo
18.
Anal Chem ; 84(14): 6000-7, 2012 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-22746183

RESUMEN

In the search for a replacement for fossil fuel and the valuable chemicals currently obtained from crude oil, lignocellulosic biomass has become a promising candidate as an alternative biorenewable source for crude oil. Hence, many research efforts focus on the extraction, degradation, and catalytic transformation of lignin, hemicellulose, and cellulose. Unfortunately, these processes result in the production of very complex mixtures. Further, while methods have been developed for the analysis of mixtures of oligosaccharides, this is not true for the complex mixtures generated upon degradation of lignin. For example, high-performance liquid chromatography/multiple stage tandem mass spectrometry (HPLC/MS(n)), a tool proven to be invaluable in the analysis of complex mixtures derived from many other biopolymers, such as proteins and DNA, has not been implemented for lignin degradation products. In this study, we have developed an HPLC separation method for lignin degradation products that is amenable to negative-ion-mode electrospray ionization (ESI doped with NaOH), the best method identified thus far for ionization of lignin-related model compounds without fragmentation. The separated and ionized compounds are then analyzed by MS(3) experiments to obtain detailed structural information while simultaneously performing high-resolution measurements to determine their elemental compositions in the two parts of a commercial linear quadrupole ion trap/Fourier-transform ion cyclotron resonance mass spectrometer. A lignin degradation product mixture was analyzed using this method, and molecular structures were proposed for some components. This methodology significantly improves the ability to analyze complex product mixtures that result from degraded lignin.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Hidróxidos/química , Lignina/química , Espectrometría de Masa por Ionización de Electrospray/métodos , Espectrometría de Masas en Tándem/métodos , Límite de Detección , Solventes/química
19.
J Fluid Mech ; 9372022 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-35250050

RESUMEN

We investigate the formation and stability of a pair of identical soft capsules in channel flow under mild inertia. We employ a combination of the lattice Boltzmann, finite element and immersed boundary methods to simulate the elastic particles in flow. Validation tests show excellent agreement with numerical results obtained by other research groups. Our results reveal new trajectory types that have not been observed for pairs of rigid particles. While particle softness increases the likelihood of a stable pair forming, the pair stability is determined by the lateral position of the particles. A key finding is that stabilisation of the axial distance occurs after lateral migration of the particles. During the later phase of pair formation, particles undergo damped oscillations that are independent of initial conditions. These damped oscillations are driven by a strong hydrodynamic coupling of the particle dynamics, particle inertia and viscous dissipation. While the frequency and damping coefficient of the oscillations depend on particle softness, the pair formation time is largely determined by the initial particle positions: the time to form a stable pair grows exponentially with the initial axial distance. Our results demonstrate that particle softness has a strong impact on the behaviour of particle pairs. The findings could have significant ramifications for microfluidic applications where a constant and reliable axial distance between particles is required, such as flow cytometry.

20.
Org Lett ; 24(32): 6049-6053, 2022 08 19.
Artículo en Inglés | MEDLINE | ID: mdl-35938947

RESUMEN

Lipoxins are important drivers of inflammation resolution, suggesting a potential therapeutic benefit. Bicyclo[1.1.1]pentanes (BCPs) are potential isosteric replacements for arenes and/or alkyl groups within drug candidates. We carried out an asymmetric synthesis of four BCP-containing synthetic lipoxin A4 mimetics (BCP-sLXms) in which the key steps were a Suzuki coupling, an asymmetric ketone reduction, and a triethylborane-initiated radical bicyclopentylation. These mimetics were screened for their impact on inflammatory responses, and one imidazolo-BCP-sLXm (6a) was found to possess high anti-inflammatory activity.


Asunto(s)
Lipoxinas , Antiinflamatorios , Humanos , Inflamación , Lipoxinas/farmacología , Pentanos
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