bluuebunny/crossref_metadata_2025 huggingface dataset:
Two separate, but interacting, neural systems for familiarity and novelty detection: A dual‐route mechanism
Authors: Kafkas Alexandros , Montaldi Daniela
Published: January 2014

It has long been assumed that familiarity‐ and novelty‐related processes fall on a single continuum drawing on the same cognitive and neural mechanisms. The possibility that familiarity and novelty processing involve distinct neural networks was explored in a functional magnetic resonance imaging study (fMRI), in which familiarity and novelty judgments were made in contexts emphasizing either familiarity or novelty decisions. Parametrically modulated BOLD responses to familiarity and novelty strength were isolated in two separate, nonoverlapping brain networks. The novelty system involved brain regions along the ventral visual stream, the hippocampus, and the perirhinal and parahippocampal cortices. The familiarity system, on the other hand, involved the dorsomedial thalamic nucleus, and regions within the medial prefrontal cortex and the medial and lateral parietal cortex. Convergence of the two networks, treating familiarity and novelty as a single continuum was only found in a fronto‐parietal network. Finally, the orbitomedial prefrontal cortex was found to be sensitive to reported strength/confidence, irrespective of stimulus' familiarity or novelty. This pattern of results suggests a dual‐route mechanism supported by the existence of two distinct but interacting functional systems for familiarity and novelty. Overall, these findings challenge current assumptions regarding the neural systems that support the processing of novel and familiar information, and have important implications for research into the neural bases of recognition memory. © 2014 Wiley Periodicals, Inc.
Subregion‐specific decreases in hippocampal serotonin transporter protein expression and function associated with endophenotypes of depression
Authors: Tang Man , He Tao , Sun Xiao , Meng Qing‐Yan , Diao Yao , Lei Jie‐Yu , He Xiao‐Jing , Chen Lei , Sang Xiu‐Bo , Zhao Shulei
Published: January 2014

Stress influences the development of depression, and depression is associated with structural and functional changes in the hippocampus. The current study sought to determine whether chronic corticosteroid (CORT) treatment influences serotonin transporter (5‐HTT) protein expression and function in the CA1, CA3, and dentate gyrus (DG) subregions of the hippocampus. Male CD‐1 mice were subcutaneously injected with CORT at a dose of 20 mg/kg once daily for 3 weeks. Behavioral state was assessed using sucrose preference, physical state of the coat, forced swimming test, and tail suspension test. We then determine 5‐HTT protein expression and synaptosomal 5‐HT uptake in the CA1, CA3 and DG subregions. CORT treatment induced anhedonia and behavioral despair, two core endophenotypes of clinical depression; 5‐HTT protein expression levels and synaptosomal 5‐HT uptake were both decreased in a subregion‐specific manner, with the greatest decrease observed in the DG, a moderate decrease in the CA3, and the CA1 showed no apparent change. In addition, a reduction in tissue mass was detected in the DG following the CORT treatment. These data indicate that subregion‐specific decreases in hippocampal 5‐HTT protein expression and function are associated with endophenotypes of depression. © 2014 Wiley Periodicals, Inc.
Characterizing context‐dependent differential firing activity in the hippocampus and entorhinal cortex
Authors: Prerau Michael J. , Lipton Paul A. , Eichenbaum Howard B. , Eden Uri T.
Published: January 2014

The rat hippocampus and entorhinal cortex have been shown to possess neurons with place fields that modulate their firing properties under different behavioral contexts. Such context‐dependent changes in neural activity are commonly studied through electrophysiological experiments in which a rat performs a continuous spatial alternation task on a T‐maze. Previous research has analyzed context‐based differential firing during this task by describing differences in the mean firing activity between left‐turn and right‐turn experimental trials. In this article, we develop qualitative and quantitative methods to characterize and compare changes in trial‐to‐trial firing rate variability for sets of experimental contexts. We apply these methods to cells in the CA1 region of hippocampus and in the dorsocaudal medial entorhinal cortex (dcMEC), characterizing the context‐dependent differences in spiking activity during spatial alternation. We identify a subset of cells with context‐dependent changes in firing rate variability. Additionally, we show that dcMEC populations encode turn direction uniformly throughout the T‐maze stem, whereas CA1 populations encode context at major waypoints in the spatial trajectory. Our results suggest scenarios in which individual cells that sparsely provide information on turn direction might combine in the aggregate to produce a robust population encoding. © 2014 Wiley Periodicals, Inc.
Behavioral anxiolysis without reduction of hippocampal theta frequency after histamine application in the lateral septum of rats
Authors: Chee San‐San A. , Menard Janet L. , Dringenberg Hans C.
Published: January 2014

Hippocampal theta activity is linked to various processes, including locomotion, learning and memory, and defense and affect (i.e., fear and anxiety). Interestingly, all classes of clinically effective anxiolytics, as well as experimental compounds that decrease anxiety in pre‐clinical animal models of anxiety, reduce the frequency of hippocampal theta activity elicited by stimulation of the reticular formation in freely behaving or anesthetized animals. In the present experiments, we found that bilateral histamine infusions (0.5 µg/hemisphere) into the lateral septum (LS) of rats decreased anxiety‐like responses in two models of anxiety, the elevated plus maze and novelty‐induced suppression of feeding test. Surprisingly, these same infusions significantly increased hippocampal theta frequency elicited by reticular stimulation in urethane‐anesthetized rats. In contrast to these findings, additional experiments showed that the clinically effective anxiolytic buspirone (40 mg/kg, i.p.) reduced theta frequency, confirming previous observations. Taken together, the dissociation of behavioral anxiolysis and theta frequency reduction noted here suggest that hippocampal theta frequency is not a direct index of anxiety levels in rodents. Further, the mechanisms underlying the behavioral and physiological effects elicited by histamine in the LS require further study. © 2014 Wiley Periodicals, Inc.
Differential mechanisms of CDKN2A (p16) alteration in oral tongue squamous cell carcinomas and correlation with patient outcome
Authors: Lim Annette M. , Do Hongdo , Young Richard J. , Wong Stephen Q. , Angel Christopher , Collins Marnie , Takano Elena A. , Corry June , Wiesenfeld David , Kleid Stephen , Sigston Elizabeth , Lyons Bernard , Fox Stephen B. , Rischin Danny , Dobrovic Alexander , Solomon Benjamin
Published: January 2014

CDKN2A (p16) disruption is reported as a frequent event in head and neck squamous cell carcinomas that confers poor prognosis. We investigated the frequency of different potential mechanisms of CDKN2A inactivation in oral tongue squamous cell carcinomas (OTSCC) and their impact on patient outcome. From a cohort of 153 OTSCC patients, 131 formalin fixed paraffin embedded blocks of pre‐treatment primary tumours were suitable for further molecular analysis. We assessed CDKN2A (p16) levels by immunohistochemistry (IHC), promoter methylation status by methylation‐sensitive high resolution melting, mutation status by Sanger sequencing, gene copy number variation by fluorescence in situ hybridisation, and correlated these with patient outcome. We found that the majority of OTSCC did not overexpress p16 (110/116, 95%), assessed by IHC. The frequency of CDKN2A mutations was 20% (21/103), homozygous loss was 7% (7/97), hemizygous loss 31% (30/97), and promoter methylation was 18% (20/113). We found no evidence of these mechanisms in 24/106 (23%) p16 IHC negative tumours. No significant correlation was identified between any potential mechanism of CDKN2A inactivation and clinical features, including smoking status and age. There was a non‐significant trend for worse overall survival for p16 IHC negative patients versus positive patients (HR = 1.81, 95% CI = 0.44–7.47, p = 0.40). No relationship was found between mechanisms of CDKN2A disruption and patient outcome. In conclusion, we demonstrate that CDKN2A alteration is a frequent event in OTSCC tumourigenesis. However, no correlation was identified between different potential mechanisms of CDKN2A disruption and clinical characteristics or patient outcome.
Cannabidiol: An Overview of Some Pharmacological Aspects
Authors: Mechoulam Raphael , Parker Linda A. , Gallily Ruth
Published: January 2014

Over the past few years, considerable attention has focused on cannabidiol (CBD), a major nonpsychotropic constituent of cannabis. The authors present a review on the chemistry of CBD and discuss the anticonvulsive, antianxiety, antipsychotic, antinausea, and antirheumatoid arthritic properties of CBD. CBD does not bind to the known cannabinoid receptors, and its mechanism of action is yet unknown. It is possible that, in part at least, its effects are due to its recently discovered inhibition of anandamide uptake and hydrolysis and to its antioxidative effect.
Effects of Smoked Marijuana in Healthy and HIV+ Marijuana Smokers
Authors: Haney Margaret
Published: January 2014

This article presents data from two avenues of marijuana research. First, the author shows that daily marijuana smoking in healthy individuals produces dependence, as demonstrated by withdrawal symptoms such as increased irritability and depression and decreased food intake. In addition, two antidepressant medications were evaluated to assess their potential effectiveness in the treatment of marijuana withdrawal symptoms: (1) sustained‐release bupropion (0, 300 mg/day) and (2) nefazodone (0, 450 mg/day). Research participants were regular marijuana smokers who lived in a residential laboratory in groups of two to four. While inpatients, participants smoked active marijuana (2.8%‐3.1% THC) repeatedly for 4 days, followed by 8 to 12 days of placebo marijuana (0.0% THC). Results show that during marijuana abstinence, (1) bupropion increased ratings of irritability, depression, and stomach pain and decreased food intake and sleep quality compared to placebo maintenance, and (2) nefazodone decreased anxiety during marijuana withdrawal but did not alter ratings of irritability and misery. Thus, neither medication showed promise as potential treatments for symptoms of marijuana withdrawal. The second avenue of research focused on the effect of cannabinoids in individuals with muscle mass loss, an indicator of wasting in HIV illness. Given that there are little scientific data contributing to the debates concerning medical marijuana, this study directly compared the effects of oral Δ9‐THC (0, 10, 20, 30 mg PO) to smoked marijuana (0.0%, 1.8%, 2.8%, 3.9% THC) in HIV+ marijuana smokers with muscle mass loss (< 90% body cell mass/height). Multiple dimensions of human behavior were measured, including food intake, mood, and cognitive performance. Drugs were administered using a within‐subject, double‐blind, staggered, double‐dummy design. Participants were free to self‐select from a variety of foods throughout most of the session. Preliminary data (n = 9) suggest that oral THC was more effective at increasing food intake, but the volunteers “liked” the effects of smoked marijuana more than the effects of oral THC.
Cognitive Measures in Long‐Term Cannabis Users
Authors: Pope Harrison G. , Gruber Amanda J. , Hudson James I. , Huestis Marilyn A. , Yurgelun‐Todd Deborah
Published: January 2014

The cognitive effects of long‐term cannabis use are insufficiently understood. Most studies concur that cognitive deficits persist at least several days after stopping heavy cannabis use. But studies differ on whether such deficits persist long term or whether they are correlated with increasing duration of lifetime cannabis use. The authors administered neuropsychological tests to 77 current heavy cannabis users who had smoked cannabis at least 5000 times in their lives, and to 87 control subjects who had smoked no more than 50 times in their lives. The heavy smokers showed deficits on memory of word lists on Days 0, 1, and 7 of a supervised abstinence period. By Day 28, however, few significant differences were found between users and controls on the test measures, and there were few significant associations between total lifetime cannabis consumption and test performance. Although these findings may be affected by residual confounding, as in all retrospective studies, they suggest that cannabis‐associated cognitive deficits are reversible and related to recent cannabis exposure rather than irreversible and related to cumulative lifetime use.
Cardiovascular System Effects of Marijuana
Authors: Jones Reese T.
Published: January 2014

Marijuana and Δ9‐tetrahydrocannabinol (THC) increase heart rate, slightly increase supine blood pressure, and on occasion produce marked orthostatic hypotension. Cardiovascular effects in animals are different, with bradycardia and hypotension the most typical response. Cardiac output increases, and peripheral vascular resistance and maximum exercise performance decrease. Tolerance to most of the initial cardiovascular effects appears rapidly. With repeated exposure, supine blood pressure decreases slightly, orthostatic hypotension disappears, blood volume increases, heart rate slows, and circulatory responses to exercise and Valsalva maneuver are diminished, consistent with centrally mediated, reduced sympathetic, and enhanced parasympathetic activity. Receptor‐mediated and probably nonneuronal sites of action account for cannabinoid effects. The endocannabinoid system appears important in the modulation of many vascular functions. Marijuana's cardiovascular effects are not associated with serious health problems for most young, healthy users, although occasional myocardial infarction, stroke, and other adverse cardiovascular events are reported. Marijuana smoking by people with cardiovascular disease poses health risks because of the consequences of the resulting increased cardiac work, increased catecholamine levels, carboxyhemoglobin, and postural hypotension.
Cardiovascular Consequences of Marijuana Use
Authors: Sidney Stephen
Published: January 2014

This review describes what is known about effects of marijuana and cannabinoids in relation to human physiological and disease outcomes. The acute physiological effects of marijuana include a substantial dose‐dependent increase in heart rate, generally associated with a mild increase in blood pressure. Orthostatic hypotension may occur acutely as a result of decreased vascular resistance. Smoking marijuana decreases exercise test duration in maximal exercise tests, increases the heart rate at submaximal levels of exercise. Tolerance develops to the acute effects of marijuana smoking and Δ9‐tetrahydrocannibol (THC) over several days to a few weeks. The cardiovascular responses that occur in response to THC are mediated by the autonomic nervous system, with recent findings also demonstrating that the human cannabinoid receptor system plays a role in regulating the cardiovascular response. Although several mechanisms exist by which marijuana use might contribute to the development of chronic cardiovascular conditions or acutely trigger cardiovascular events, there are few data regarding marijuana/THC use and cardiovascular disease outcomes. A large cohort study showed no association of marijuana use with cardiovascular disease hospitalization or mortality. However, acute effects of marijuana use include a decrease of the time until the onset of chest pain in patients with angina pectoris; one study has shown that marijuana may trigger the onset of myocardial infarction. Patients who have coronary heart disease or are at high risk for the development of CHD should be cautioned about the potential hazards of marijuana use as a precipitant for clinical events. Research directions might include more studies of cardiovascular disease outcomes and relationships of marijuana with cardiovascular risk factors, studies of metabolic and physiologic effects of chronic marijuana use that may affect cardiovascular disease risk, increased understanding of the role of the cannabinoid receptor system in cardiovascular regulation, and studies to determine if there is a therapeutic role for cannabinoids in blood pressure control or for neuroprotection after stroke.
Respiratory and Immunologic Consequences of Marijuana Smoking
Authors: Tashkin Donald P. , Baldwin Gayle C. , Sarafian Theodore , Dubinett Steven , Roth Michael D.
Published: January 2014

Habitual smoking of marijuana has a number of effects on the respiratory and immune systems that may be clinically relevant. These include alterations in lung function ranging from no to mild airflow obstruction without evidence of diffusion impairment, an increased prevalence of acute and chronic bronchitis, striking endoscopic findings of airway injury (erythema, edema, and increased secretions) that correlate with histopathological alterations in bronchial biopsies, and dysregulated growth of the bronchial epithelium associated with altered expression of nuclear and cytoplasmic proteins involved in the pathogenesis of bronchogenic carcinoma. Other consequences of regular marijuana use include ultrastructual abnormalities in human alveolar macrophages along with impairment of their cytokine production, antimicrobial activity, and tumoricidal function. Cannabinoid receptor expression is altered in leukocytes collected from the blood of chronic smokers, and experimental models support a role for Δ9‐tetrahydrocannabinol in suppressing T cell function and cell‐mediated immunity. The potential for marijuana smoking to predispose to the development of respiratory malignancy is suggested by several lines of evidence, including the presence of potent carcinogens in marijuana smoke and their resulting deposition in the lung, the occurrence of premalignant changes in bronchial biopsies obtained from smokers of marijuana in the absence of tobacco, impairment of antitumor immune defenses by Δ9‐tetrahydrocannabinol, and several clinical case series in which marijuana smokers were disproportionately overrepresented among young individuals who developed upper or lower respiratory tract cancer. Additional well‐designed epidemiological and immune monitoring studies are required to determine the potential causal relationship between marijuana use and the development of respiratory infection and/or cancer.
A further evaluation of behavioral skills training for implementation of the picture exchange communication system
Authors: Homlitas Christa , Rosales Rocío , Candel Lindsay
Published: January 2014

We evaluated the effectiveness of a behavioral skills training package to teach implementation of Phases 1, 2, and 3A of the picture exchange communication system (PECS) to teachers employed at a therapeutic center for children with autism. Probes in the natural environment and follow‐up were conducted with children who were assigned to work with the teachers in their own classrooms. Results provide additional support for the efficacy of behavioral skills training to teach implementation of PECS.
Five Freely Circulating miRNAs and Bone Tissue miRNAs Are Associated With Osteoporotic Fractures
Authors: Seeliger Claudine , Karpinski Katrin , Haug Alexander T , Vester Helen , Schmitt Andreas , Bauer Jan S , van Griensven Martijn
Published: January 2014

Osteoporosis as a systemic skeletal disorder is characterized by increased bone fragility and the risk of fractures. According to the World Health Organization, osteoporosis is one of the 10 most common diseases and affects approximately 75 million people in Europe, the United States, and Japan. In this context, the identification of specific microRNA (miRNA) signatures is an important step for new diagnostic and therapeutic approaches. The focus of interest on miRNAs as biomarkers came with new publications identifying free circulating extracellular miRNAs associated with various types of cancer. This study aimed to identify specific miRNAs in patients with osteoporotic fractures compared with nonosteoporotic fractures. For the array analysis, miRNAs were isolated from the serum of 20 patients with hip fractures, transcribed, and the samples were pooled into 10 osteoporotic and 10 nonosteoporotic specimens. With each pool of samples, human serum and plasma miRNA PCR arrays were performed, which are able to identify 83 different miRNAs. Subsequently, a separate validation analysis of each miRNA found to be regulated in the array followed with miRNA samples isolated from the serum of 30 osteoporotic and 30 nonosteoporotic patients and miRNA samples isolated from the bone tissue of 20 osteoporotic and 20 nonosteoporotic patients. With the validation analysis of the regulated miRNAs, we identified 9 miRNAs, namely miR-21, miR-23a, miR-24, miR-93, miR-100, miR-122a, miR-124a, miR-125b, and miR-148a, that were significantly upregulated in the serum of patients with osteoporosis. In the bone tissue of osteoporotic patients, we identified that miR-21, miR-23a, miR-24, miR-25, miR-100, and miR-125b displayed a significantly higher expression. A total of 5 miRNAs display an upregulation both in serum and bone tissue. This study reveals an important role for several miRNAs in osteoporotic patients and suggested that they may be used as biomarkers for diagnostic purposes and may be a target for treating bone loss and optimizing fracture healing in osteoporotic patients. © 2014 American Society for Bone and Mineral Research.
Tl+ Showed Negligible Interaction with Inner Membrane Sulfhydryl Groups of Rat Liver Mitochondria, but Formed Complexes with Matrix Proteins
Authors: Korotkov Sergey M. , Brailovskaya Irina V. , Kormilitsyn Boris N. , Furaev Viktor V.
Published: January 2014

The effects of Tl+ on protein sulfhydryl (SH) groups, swelling, and respiration of rat liver mitochondria (RLM) were studied in a medium containing TlNO3 and sucrose, or TlNO3 and KNO3 as well as glutamate plus malate, or succinate plus rotenone. Detected with Ellman's reagent, an increase in the content of the SH groups was found in the inner membrane fraction, and a simultaneous decline was found in the content of the matrix‐soluble fraction for RLM, incubated and frozen in 25–75 mM TlNO3. This increase was greater in the medium containing KNO3 regardless of the presence of Ca2+. It was eliminated completely for RLM injected in the medium containing TlNO3 and then washed and frozen in the medium containing KNO3. Calcium‐loaded RLM showed increased swelling and decreased respiration. These results suggest that a ligand interaction of Tl+ with protein SH groups, regardless of the presence of calcium, may underlie the mechanism of thallium toxicity.
Responding by exclusion in temporal discrimination tasks
Authors: Cippola Nathália Sabaine , Domeniconi Camila , Machado Armando
Published: January 2014

Responding by exclusion, one of the most robust phenomena in Experimental Psychology, describes a particular form of responding observed in symbolic, matching‐to‐sample tasks. Given two comparison stimuli, one experimentally defined and one experimentally undefined, the participant prefers the undefined comparison following an undefined sample. The goal of the present study was to determine whether responding by exclusion could be obtained using samples that varied along a single dimension. Using a double temporal bisection task, 10 university students learned to choose visual comparisons (colored circles) based on the duration of a tone. In tests of exclusion, sample stimuli with new durations were followed by comparison sets that included one previously trained, defined comparison (colored circle) and one previously untrained, undefined comparison (geometric shape). Participants preferred the defined comparisons following the defined samples and the undefined comparisons following the undefined samples, the choice pattern typical of responding by exclusion. The use of samples varying along a single dimension allows us to study the interaction between stimulus generalization gradients and exclusion in the control of conditional responding.
Pausing as an operant: Choice and discriminated responding
Authors: Craig Andrew R. , Lattal Kennon A. , Hall Ezra G.
Published: January 2014

The effects of intermittent schedules of reinforcement for pausing were evaluated in two experiments. In Experiment 1, across a series of conditions, a variable‐interval (VI) baseline schedule, in which pigeons' key pecks produced food, alternated with conditions in which food was delivered according to a concurrent VI (for key pecking) tandem variable‐time differential‐reinforcement‐of‐other‐behavior (DRO) 5‐s schedule. Time spent pausing within a session was proportional to the reinforcement rates associated with the tandem schedule. To examine the control of pausing by antecedent events, Experiment 2 arranged a multiple schedule in which pecking and pausing in either component were maintained according to concurrent schedules like those used in the first experiment. The availability of reinforcement for pausing was signaled in one component while signals uncorrelated with reinforcement were presented in the other. Signaled reinforcement for pausing, relative to the presentation of uncorrelated signals, decreased time spent pausing, a finding consistent with existing research on the effects of signaled VI reinforcement for key pecking in pigeons. The results of the two experiments show that pausing functions as an operant in much the same way that discrete responses, like key pecks, do, and that pausing and other operants are similarly affected by both antecedent and consequent events.
Degree Conditions for Spanning Brooms
Authors: Chen Guantao , Ferrara Michael , Hu Zhiquan , Jacobson Michael , Liu Huiqing
Published: January 2014

A broom is a tree obtained by subdividing one edge of the star an arbitrary number of times. In (E. Flandrin, T. Kaiser, R. Kužel, H. Li and Z. Ryjáček, Neighborhood Unions and Extremal Spanning Trees, Discrete Math 308 (2008), 2343–2350) Flandrin et al. posed the problem of determining degree conditions that ensure a connected graph G contains a spanning tree that is a broom. In this article, we give one solution to this problem by demonstrating that if G is a connected graph of order with , then G contains a spanning broom. This result is best possible.
Microscopic analysis of the localization of two chlorin‐based photosensitizers in OSC19 tumors in the mouse oral cavity
Authors: van Leeuwen–van Zaane Floor , van Driel Pieter B.A.A. , Gamm Ute A. , Snoeks Thomas J.A. , de Bruijn Henriëtte S. , van der Ploeg–van den Heuvel Angelique , Löwik Clemens W.G.M. , Sterenborg Henricus J.C.M. , Amelink Arjen , Robinson Dominic J.
Published: January 2014

Background and Objective

The effect of photodynamic therapy (PDT) is dependent on the localization of photosensitizer in the treatment volume at the time of illumination. Investigation of photosensitizer pharmacokinetics in and around the treatment volume aids in determining the optimal drug light interval for PDT.

Materials and Methods

In this paper we have investigated the distribution of the photosensitizers chlorin e6 and Bremachlorin in the oral squamous cell carcinoma cell‐line OSC19‐Luc‐Gfp in a tongue tumor, tumor boundary, invasive tumor boundary, and normal tongue tissue by the use of confocal microscopy of frozen sections. Tongues were harvested at t = [3, 4.5, 6, 24, 48] hours after injection.

Results

Both photosensitizers showed a decreasing fluorescence with increasing incubation time, and at all time points higher fluorescence was measured in tumor boundary than in tumor itself. For short incubation times, a higher fluorescence intensity was observed in the invasive tumor border and normal tissue compared to tumor tissue. Bremachlorin showed a small increase in tumor to normal ratio at 24 and 48 hours incubation time. Ce6 was undetectable at 48 hours. We did not find a correlation between photosensitizer localization and the presence of vasculature.

Conclusion

The modest tumor/tumor boundary to normal selectivity of between 1.2 and 2.5 exhibited by Bremachlorin 24 and 48 hours after administration may allow selective targeting of tongue tumors. Further studies investigating the relationship between Bremachlorin concentration and therapeutic efficacy PDT with long incubation times are warranted. Lasers Surg. Med. 46:224–234, 2014. © 2013 Wiley Periodicals, Inc.
A New Thermosensitive Poly(N‐propionyl‐aspartic acid/ethylene glycol) with No Cytotoxicity and Tunable UCST
Authors: Di Yingying , Ma Xin , Li Chunxiu , Liu Hongmei , Fan Xueying , Wang Meng , Deng Heying , Jiang Ting , Yin Ziming , Deng Kuilin
Published: January 2014

A new thermosensitive poly(N‐propionyl‐aspartic acid/ethylene glycol) (PPAE) with no cytotoxicity and an upper critical solution temperature (UCST) is synthesized by polycondensation of l‐aspartic acid and ethylene glycol. The chemical structures of the monomer and polymer are confirmed by FTIR and 1H NMR spectroscopy, and by elemental analysis measurements. Turbidimetric measurements indicate that PPAE shows a reversible UCST phase transition at 1.5–37.6 °C in pure water or an alcohol/water mixture. The UCST can be facilely tuned via changing the content of alcohol in water or the normal saline. Moreover, the survival rate of HeLa cells to PPAE is close to 100% within 48 h, demonstrating no cytotoxicity. Such aspartic acid‐based polymers with tunable thermosensitivity could be useful in the biomedical field.

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Star‐Like Dextran‐graft‐(polyacrylamide‐co‐polyacrylic acid) Copolymers
Authors: Kutsevol Nataliya , Bezuglyi Mykola , Bezugla Tetiana , Rawiso Michel
Published: January 2014

Star‐like dextran‐graft‐(polyacrylamide‐co‐polyacrylic acid) (D‐g‐(PAA‐co‐PAAc) copolymers in a salt form were obtained by alkaline hydrolysis of Dextran‐graft‐Polyacrylamide (D‐g‐PAA) samples. The internal structure of D‐g‐PAA in solution predetermined the reaction course and the conversion degree depended upon the initial architecture of macromolecules. It was shown that macromolecules of D‐g‐(PAA‐co‐PAAc) acquired extended conformation because grafted chains became greatly straightened when charged functional groups appeared. No polyelectrolyte effect for synthesized D‐g‐(PAA‐co‐PAAc) samples was registered. Star‐like polyelectrolytes were proved to be more efficient matrices in comparison with linear anionic Polyacrylamide for silver nanoparticle in situ synthesis.
Controlled Aggregation of Biopolymer‐Wrapped Carbon Nanotubes in Aqueous Suspension, Induced by Cationic Porphyrin
Authors: Zarudnev E. S. , Karachevtsev V. A.
Published: January 2014

Unusual aggregation of biopolymer‐wrapped single‐walled carbon nanotubes (SWCNTs) induced by cationic porphyrin meso‐tetrakis(4‐N‐methyl‐pyridyl)porphine (TMPyP4) in aqueous suspension has been studied by absorption spectroscopy and molecular dynamics simulation. After the addition of a small dose of TMPyP4 (10−6 M) into poly(rC):SWCNTs aqueous suspension, nanotubes begin to aggregate, but the aggregates are stable without precipitation during a few days. Spectral observations indicate that the porphyrin core stacked with π‐systems of the biopolymer:SWCNT hybrid and all nanotube species take part in this aggregate formation without any selection. Molecular dynamic simulation demonstrates that the stable complex consisting of two nanotubes can be formed when TMPyP4 molecules bound nanotubes both owing to π‐π stacking of the porphyrin core with the surface of one nanotube and with the oligonucleotide adsorbed onto another nanotube. TMPyP4 molecules not only couple the biopolymer:nanotube hybrids, but also they stitch polymer's strands wrapping around each nanotube resulting in continuous floatation of aggregates in water. It was shown that the aggregate is stable even at 373 K. At this temperature additional contacts between two neighbor's polymers appear which strengthen this aggregate too. The controlled aggregation of biopolymer‐wrapped carbon nanotubes can be employed at the fabrication of multifunctional supramolecular assemblies, photovoltaic cells and in biosensing.
Preparation of Hybrid Fe3O4/Poly(lactic‐co‐glycolic acid) (PLGA) Particles by Emulsion and Evaporation Method. Optimization of the Experimental Parameters
Authors: Pérez A. , Mijangos C. , Hernández R.
Published: January 2014

The incorporation of iron oxide nanoparticles into poly(lactic‐co‐glycolic) (PLGA) particles was carried out with an emulsion and evaporation method. To optimize the mean size and the particle size distribution of the particles, the following parameters were modulated: the molecular weight and the hydrolyzation degree of the surfactant, the concentration of the aqueous phase and the stirring rate. Samples were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and thermogravimetric analysis (TGA).
Cognitive impairment in rapid‐onset dystonia‐parkinsonism
Authors: Cook Jared F. , Hill Deborah F. , Snively Beverly M. , Boggs Niki , Suerken Cynthia K. , Haq Ihtsham , Stacy Mark , McCall W. Vaughn , Ozelius Laurie J. , Sweadner Kathleen J. , Brashear Allison
Published: January 2014

Rapid‐onset dystonia‐parkinsonism (RDP) is caused by mutations in the ATP1A3 gene. This observational study sought to determine if cognitive performance is decreased in patients with RDP compared with mutation‐negative controls. We studied 22 familial RDP patients, 3 non‐motor‐manifesting mutation‐positive family members, 29 mutation‐negative family member controls in 9 families, and 4 unrelated RDP patients, totaling 58 individuals. We administered a movement disorder assessment, including the Burke‐Fahn‐Marsden Dystonia Rating Scale (BFMDRS) and the Unified Parkinson's Disease Rating Scale (UPDRS) and a cognitive battery of memory and learning, psychomotor speed, attention, and executive function. The cognitive battery was designed to evaluate a wide range of functions; recognition memory instruments were selected to be relatively pure measures of delayed memory, devoid of significant motor or vocal production limitations. Comparisons of standardized cognitive scores were assessed both with and without controlling for psychomotor speed and similarly for severity of depressive symptoms. A majority of RDP patients had onset of motor symptoms by age 25 and had initial symptom presentation in the upper body (face, mouth, or arm). Among patients, the BFMDRS (mean ± SD, 52.1 ± 29.5) and UPDRS motor subscore (29.8 ± 12.7) confirmed dystonia‐parkinsonism. The affected RDP patients performed more poorly, on average, than mutation‐negative controls for all memory and learning, psychomotor speed, attention, and executive function scores (all P ≤ 0.01). These differences persisted after controlling for psychomotor speed and severity of depressive symptoms. Impaired cognitive function may be a manifestation of ATP1A3 mutation and RDP. © 2014 International Parkinson and Movement Disorder Society
Mathematical modeling of drug delivery from cylindrical implantable devices
Authors: Ibarra Juan C. D. , Helbling Ignacio M. , Luna Julio A.
Published: January 2014

A mechanistic mathematical model applicable to the controlled dispersed‐drug release from cylindrical device such as implantable drug delivery system was derived. Analytical solutions based on the pseudosteady state approximation are derived taken account an exact external medium volume. The model prediction is accurate when the initial drug load is higher than the drug solubility in the polymer. The results obtained are compared with the analytical solutions available in the literature. The equations are corroborated by comparison with experimental profiles reported in the literature for sink conditions and non sink conditions. The evolution of concentration distribution profiles is compared for different volume of external medium. A reduction in the volume of the external solution leads to an increase in the concentration on the surface of the device, which determines decreases in the release of drug. One criterion for determining whether the volume of external solution should be considered for the prediction of drug release from cylindrical devices is established. This criterion is based on establishing a maximum percentage error allowed in the values of amount of drug released. The usefulness of the model is focused in the design of implant for controlled release of drug into a small volume of external medium of release. Copyright © 2014 John Wiley & Sons, Ltd.
A note on the instability of a focusing nonlinear damped wave equation
Authors: Saanouni T.
Published: January 2014

We investigate the initial value problem for a nonlinear damped wave equation in two space dimensions. We prove local well‐posedness and instability by blow‐up of the standing waves. Copyright © 2014 John Wiley & Sons, Ltd.
On a bi‐nonlocal p(x)‐Kirchhoff equation via Krasnoselskii's genus
Authors: Corrêa Francisco Julio S.A. , dos Reis Costa Augusto César
Published: January 2014

We study existence and multiplicity of solutions to the following bi‐nonlocal p(x)‐Kirchhoff equation via Krasnoselskii's genus, on the Sobolev space with variable exponent,
urn:x-wiley:1704214:media:mma3051:mma3051-math-0001
where Ω is a bounded smooth domain of I RN, 1 < p(x) < N, M and f are continuous functions, f is an odd function, and r > 0 is a real parameter. Copyright © 2014 John Wiley & Sons, Ltd.
Closed form solution of electromagnetic wave diffraction problem in a homogeneous bi‐isotropic medium
Authors: Nawaz Rab , Ayub Muhammad
Published: January 2014

In this study, the problem of wave scattering of an electromagnetic field in a homogeneous bi‐isotropic medium by a perfectly conducting strip is theoretically analyzed. The crux of the study is a rigorous construction of a closed form solution in the complex domain. A series solution of electromagnetic plane wave diffraction problem in terms of the eigenfunctions that happen to be the generalized Gamma functions is found. In the transformed domain, the scattered field is physically interpreted by computing the convergence history, and thereby, higher order accurate solution has been obtained in complex domain in closed form. Copyright © 2014 John Wiley & Sons, Ltd.
Abundant explicit exact solutions to the generalized nonlinear Schrödinger equation with parabolic law and dual‐power law nonlinearities
Authors: Zheng Xiaoxiao , Shang Yadong
Published: January 2014

This paper is concerned with the generalized nonlinear Schrödinger equation with parabolic law and dual‐power law. Abundant explicit and exact solutions of the generalized nonlinear Schrödinger equation with parabolic law and dual‐power law are derived uniformly by using the first integral method. These exact solutions are include that of extended hyperbolic function solutions, periodic wave solutions of triangle functions type, exponential form solution, and complex hyperbolic trigonometric function solutions and so on. The results obtained confirm that the first integral method is an efficient technique for analytic treatment of a wide variety of nonlinear systems of partial DEs. Copyright © 2014 John Wiley & Sons, Ltd.
Dynamics analysis of a quarantine model in two patches
Authors: Safi Mohammad A. , Gumel Abba B.
Published: January 2014

A new deterministic model for assessing the impact of quarantine on the transmission dynamics of a communicable disease in a two‐patch community is designed. Rigorous analysis of the model shows that the imperfect nature of quarantine (in the two patches) could induce the phenomenon of backward bifurcation when the associated reproduction number of the model is less than unity. For the case when quarantined susceptible individuals do not acquire infection during quarantine, the disease‐free equilibrium of the model is shown to be globally asymptotically stable when the associated reproduction number is less than unity. Furthermore, the model has a unique Patch i‐only boundary equilibrium (i = 1,2) whenever the associated reproduction number for Patch i is greater than unity. The unique Patch i‐only boundary equilibrium is locally asymptotically stable whenever the invasion reproduction number of Patch 3 − i is less than unity (and the associated reproduction number for Patch i exceeds unity). The model has at least one endemic equilibrium when its reproduction number exceeds unity (and the disease persists in both patches in this case). It is shown that adding multi‐patch dynamics to a single‐patch quarantine model (which allow the quarantine of susceptible individuals) in a single patch does not alter its quantitative dynamics (with respect to the existence and asymptotic stability of its associated equilibria as well as its backward bifurcation property). Copyright © 2014 John Wiley & Sons, Ltd.
A new look at the construct validity of the K6 using Rasch analysis
Authors: Khan Asaduzzaman , Chien Chi‐Wen , Burton Nicola W.
Published: January 2014

The Kessler six‐item psychological distress (K6) scale is widely used to screen for mental disorders; however, information is lacking on the rating scale performance or dimensionality structure of the scale. This study used a population based sample (n = 7596) to evaluate the construct validity of the K6 scale using Rasch partial credit analysis. The analysis showed that almost all of the five‐point rating scales in the K6 items were used appropriately to differentiate psychological distress of the study participants. The analysis provided evidence of unidimensionality of the scale, although items 1 (so sad) and 3 (restless or fidgety) might offer a potential second off‐dimensional component. All items appeared to fit the Rasch model's expectation as demonstrated by the acceptable item fit statistics. The study participants demonstrated valid response patterns when answering K6 items, except for some who were younger or had higher psychological distress. This study using Rasch analysis confirms the construct validity of the K6 scale and suggests that the K6 is a useful and valid instrument for assessing psychological distress in the mid‐aged general population. Further research can facilitate better understanding about the unidimensionality of the scale. Copyright © 2014 John Wiley & Sons, Ltd.
Structural analysis of an impurity of the drug landiolol
Authors: Štujber Michal , Beldar Sagar , Rabong Constantin , Beseda Igor , Breza Martin , Liptaj Tibor
Published: January 2014

In a course of development and preparation of landiolol (1a), a known ultra‐short‐acting β‐blocker, process quality control by HPLC and LC‐MS analysis consistently showed an impurity peak ranging from 0.05% to 0.15 % and exhibiting a molecular mass m/z 887. To identify the hitherto unknown impurity, we prepared one of the possible landiolol derivatives with the same molecular mass for proper spectral characterization (NMR and MS). Its equivalence with the unknown impurity was then confirmed by LC‐MS analysis. Ultimately, using fragmentation patterns in LC‐MS and selective two‐dimensional NMR experiments, the structure of the impurity was assigned as [(4S)‐2,2‐dimethyl‐1,3‐dioxolan‐4‐yl]methyl 3‐{4‐[(2S)‐2‐hydroxy‐3‐(3‐{4‐[(2S)‐2‐hydroxy‐3‐[(2‐{[(morpholin‐4‐yl)carbonyl]amino}ethyl)amino]propoxy]phenyl}‐N‐(2‐{[(morpholin‐4‐yl)carbonyl]amino}ethyl)propanamido)propoxy]phenyl}propanoate (2). It was found that the impurity was present in two rotameric forms at room temperature. The synthesis and NMR characterization of (2) are discussed. Copyright © 2014 John Wiley & Sons, Ltd.
Analysis of proton‐density bias corrections based on T1 measurement for robust quantification of water content in the brain at 3 Tesla
Authors: Abbas Zaheer , Gras Vincent , Möllenhoff Klaus , Keil Fabian , Oros‐Peusquens Ana‐Maria , Shah Nadim J.
Published: January 2014

Purpose

Estimating tissue water content using high field MRI, such as 3 Tesla (T), is challenging due to the difficulty in dissociating the radio frequency inhomogeneity pattern from the signal arising from tissue intrinsic proton density (PD) variations. To overcome this problem the longitudinal relaxation time T1 can be combined with an initial guess of the PD to yield the desired PD bias correction. However, it is necessary to know whether T1 effects, i.e., any effect contributing to T1 while being independent of tissue hydration, influence the estimated correction.

Methods

Twenty‐five healthy subjects underwent a quantitative 3T MRI protocol enabling acquisition of 64 slices with 1 mm in‐plane resolution and 2 mm slice thickness in 14 min. Influence of T1 effects on the estimated water content map is evaluated using a dedicated method including T1 and T2* information and region of interest‐based water content values are compared with the literature.

Results

Our analysis indicates that the PD bias correction based on T1 is largely insensitive to T1 effects. Besides, water content results are in good agreement with literature values obtained at 1.5T.

Conclusion

This study demonstrates the applicability of a PD bias correction based on T1 to yield tissue water content at 3T. Magn Reson Med 72:1735–1745, 2014. © 2014 Wiley Periodicals, Inc.
Effect of carr‐purcell refocusing pulse trains on transverse relaxation times of metabolites in rat brain at 9.4 Tesla
Authors: Deelchand Dinesh Kumar , Henry Pierre‐Gilles , Marjańska Małgorzata
Published: January 2014

Purpose

To investigate the effect of Carr‐Purcell (CP) pulse trains on transverse relaxation times, T2, of tissue water and metabolites (both noncoupled and J‐coupled spins) in the rat brain at 9.4 Tesla (T) using LASER, CP‐LASER, and T2ρ‐LASER sequences.

Methods

Proton NMR spectra were measured in rat brain in vivo at 9.4T. Spectra were acquired at multiple echo times ranging from 18 to 402 ms. All spectra were analyzed using LCModel with simulated basis sets. Signals of metabolites as a function of echo time were fitted using a mono‐exponential function to determine their T2 relaxation times.

Results

Measured T2s for tissue water and all metabolites were significantly longer with CP‐LASER and T2ρ‐LASER compared with LASER. The T2 increased by a factor of ∼1.3 for noncoupled and weakly coupled spins (e.g., N‐acetylaspartate and total creatine) and by a factor of ∼2 (e.g., glutamine and taurine) to ∼4 (e.g., glutamate and myo‐inositol) for strongly coupled spins.

Conclusion

Application of a CP pulse train results in a larger increase in T2 relaxation times for strongly coupled spins than for noncoupled (singlet) and weakly coupled spins. This needs to be taken into account when correcting for T2 relaxation in CP‐like sequences such as LASER. Magn Reson Med 73:13–20, 2015. © 2014 Wiley Periodicals, Inc.