bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics and modeling of reductive dechlorination at high PCE and TCE concentrations
Authors: Yu Seungho , Semprini Lewis 
Published: September 2004

AbstractTwo biokinetic models employing the Michaelis‐Menten equation for anaerobic reductive dechlorination of tetrachloroethylene (PCE) and trichloroethylene (TCE) were developed. The models were compared with results from batch kinetic tests conducted over a wide range of PCE and TCE concentrations with two different dechlorinating cultures. One model applies Michaelis‐Menten kinetics with competitive inhibition among chlorinated aliphatic hydrocarbons (CAHs), while the other model includes both competitive inhibition and Haldane inhibition at high CAH concentrations. Model simulations with competitive inhibition simulated the experimental results well for PCE concentrations lower than 300 μM. However, simulations deviated from the experimental observations for PCE or TCE concentrations greater than 300–400 μM. The kinetic model that incorporated both competitive and Haldane inhibitions better simulated experimental data for PCE concentrations near the solubility limit (1000 μM), and TCE concentrations at half its solubility limit (4000 μM). Based on the modeling analysis of the experimental results, the PM culture (Point Mugu, CA) had very high Haldane inhibition constants for cis‐1,2‐dichlororethylene (c‐DCE) and vinyl chloride (VC) (6000 and 7000 μM, respectively), indicating very weak Haldane inhibition, while the EV culture (the Evanite site in Corvallis, OR) had lower Haldane inhibition constants for TCE, c‐DCE, and VC of 900, 750, and 750 μM, respectively. The BM culture (a binary mixed culture of the PM and EV cultures) had transformation abilities that represented the mixture of the EV and PM cultures. Model simulations of the BM culture transformation abilities were well represented by separate rate equations and model parameters for the two independent cultures that were simultaneously solved. Modeling results indicated that a combination of competitive and Haldane inhibition kinetics is required to simulate dechlorination over a broad range of concentrations up to the solubility limit of PCE and half the solubility limit of TCE. © 2004 Wiley Periodicals, Inc.
Determination of piceatannol in rat serum and liver microsomes: pharmacokinetics and phase I and II biotransformation
Authors: Roupe Kathryn , Teng Xiao Wei , Fu Xing , Meadows Gary G. , Davies Neal M. 
Published: September 2004

AbstractA method of analysis of piceatannol in biological ﬂuids is necessary to study the kinetics of in vitro and in vivo metabolism and determine its concentration in foodstuffs. A novel and simple high‐performance liquid chromatographic method was developed for simultaneous determination of piceatannol and products of its metabolism in rat serum and liver microsomes. Serum, or microsomes (0.1 mL), were precipitated with acetonitrile after addition of the internal standard, 4‐methylumbelliferone. Separation was achieved on a phenomenex C18 column (250 × 4.6 mm i.d., 5 µm) equipped with a phenomenex C18 (4 × 3.0 mm i.d., 5 µm) guardcolumn with ﬂuorescence excitation at 320 nm and emission at 420 nm. Separation was also possible with UV detection at 310 nm. The ﬂuorescent calibration curves were linear ranging from 0.05 to 100 µg/mL. The mean extraction efﬁciency was >95%. Precision of the assay was <10% (coefﬁcient of variation), and was within 10% at the limit of quantitation (0.05 ng/mL). Bias of the assay was lower than 7%. The limit of detection was 50 ng/mL for a 0.1 mL sample. The assay was applied successfully to the in vitro kinetic study of metabolism of piceatannol in rat liver microsomes and pharmacokinetics in rats. Three metabolites of piceatannol have been identiﬁed. Copyright © 2004 John Wiley & Sons, Ltd.
Study on polymerization of the pharmaceutical substances isohexenylnaphthazarins
Authors: Assimopoulou A. N. , Papageorgiou V. P. 
Published: September 2004

AbstractPolymerization of naturally occurring isohexenylnaphthazarins (IHN), such as alkannin, shikonin (A/S) and their derivatives, which are potent pharmaceutical substances, signiﬁcantly affects their use in pharmaceuticals, cosmetics and as food colorants, because it leads to reduction of the lustre of their red coloration, a decrease in their solubility and reduces the active monomeric IHN derivatives. In the present study, the inﬂuence of several crucial variables (processing and storage) was experimentally investigated on IHN polymerization by size exclusion chromatography (SEC). Temperature and solvent polarity increased signiﬁcantly the concentration of hydroxynaphthoquinone (HNQ) polymers, while air and light exposure conditions did not signiﬁcantly affect IHN polymerization. Low temperatures are proposed for all processes of industrial production of pharmaceutical preparations containing IHN and HNQ. An optimization of the industrial conditions used for the preparation of pharmaceutical and cosmetic preparations containing IHN, maximizing the active monomeric IHN fraction, was performed. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of bisphenol A in human breast milk by HPLC with column‐switching and ﬂuorescence detection
Authors: Sun Yen , Irie Miki , Kishikawa Naoya , Wada Mitsuhiro , Kuroda Naotaka , Nakashima Kenichiro 
Published: September 2004

AbstractA highly sensitive HPLC method was developed for the determination of xenoestrogenic compound, bisphenol A (BPA) in human breast milk samples. After a two‐step liquid–liquid extraction, BPA was derivatized with ﬂuorescent labeling reagent, 4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)benzoyl chloride (DIB‐Cl). The excess ﬂuorescent reagent could be removed effectively using a column‐switching system. The separation of DIB‐BPA from endogenous materials in milk was carried out on two C18 columns and ﬂuorescence intensity was monitored at 475 nm with the excitation of 350 nm. A good linearity (r = 0.994) was observed of BPA in the concentration range of 0.2–5.0 ng mL−1 in breast milk, and the detection limit was 0.11 ng mL−1 at a signal‐to‐noise ratio of 3. Intra‐ and inter‐day precision (RSD, %) were less than 8.7 and 10.4, respectively. Twenty‐three breast milk samples of healthy lactating women were analyzed for the BPA concentration; the mean value was 0.61 ± 0.20 ng mL−1, with no correlation to the lipid content of milk samples. Copyright © 2004 John Wiley & Sons, Ltd.
Study on isohexenylnaphthazarins polymerization in alkaline media
Authors: Assimopoulou A. N. , Papageorgiou V. P. 
Published: September 2004

AbstractThe chiral pair alkannin and shikonin (A/S) and their isohexenylnaphthazarin (IHN) esters, which are naturally occurring hydroxynaphthoquinones (HNQ), are potent pharmaceutical substances with a wide spectrum of biological activity. The stability of A/S and their derivatives during process and storage is crucial to their use as drugs, cosmetics and food additives. The inﬂuence of alkaline media and of IHN esters hydrolysis was experimentally investigated on IHN polymerization by size exclusion chromatography (SEC). It was proved that during IHN esters hydrolysis, polymeric A/S and IHN are formed. An optimization of the hydrolysis conditions of IHN esters was also approached in terms of polymerization. Hydrolysis of IHN from a pure mixture of pigments proved preferable to that of preliminary root extracts by means of IHN polymerization, even for analytical determination; non‐polar solvents are proposed for the extraction of IHN from roots, followed by hydrolysis, aiming to minimize the polymeric IHN and A/S formed. It was also proved that polymerization of IHN in alkaline media and during hydrolysis of IHN esters proceeds through the intermediate formation of semiquinones; after acidiﬁcation, coupling of semiquinones with phenoxyl radicals results in polymeric IHN structures. Copyright © 2004 John Wiley & Sons, Ltd.
Absolute configurational determination of an all‐trans‐retinal dimer isolated from photoreceptor outer segments
Authors: Fishkin Nathan , Pescitelli Gennaro , Sparrow Janet R. , Nakanishi Koji , Berova Nina 
Published: September 2004

AbstractAn all‐trans‐retinal (ATR) dimer (1) isolated from photoreceptor outer segments was found to have a stereogenic center at C13′ flanked by tetraene (295 nm) and hexaenal (438 nm) chromophores. Analytical chiral HPLC (Chiralcel OD) revealed that the isolated retinoid had formed in 13% enantiomeric excess. Using a combination of 1H‐1H NOESY constraints, molecular modeling, and CD exciton coupling analysis, it was determined that the favored enantiomer was 13′(R). Three low‐energy conformers of the 13′(S) model were found with MMFF/DFT and were used to calculate the CD spectrum of the ATR dimer (DeVoe method). The Boltzmann weighted spectrum was found to exhibit a positive exciton couplet, in excellent agreement with the experimental spectrum for the first eluted enantiomer. This further suggested that despite the large energy difference between the two interacting chromophores, the dominant source of optical activity in the CD spectrum is the nondegenerate exciton mechanism. Chirality 16:637–641, 2004. © 2004 Wiley‐Liss, Inc.
Enantiomers of C5‐chiral 1‐acetyl‐3,5‐diphenyl‐4,5‐dihydro‐(1H)‐pyrazole derivatives: Analytical and semipreparative HPLC separation, chiroptical properties, absolute configuration, and inhibitory activity against monoamine oxidase
Authors: Cirilli Roberto , Ferretti Rosella , Gallinella Bruno , Turchetto Luciana , Bolasco Adriana , Secci Daniela , Chimenti Paola , Pierini Marco , Fares Vincenzo , Befani Olivia , La Torre Francesco 
Published: September 2004

AbstractThe HPLC enantiomer separation of a novel series of C5‐chiral 1‐acetyl‐3‐(4‐hydroxy‐ and 2,4‐dihydroxyphenyl)‐5‐phenyl‐4,5‐dihydro‐(1H)‐pyrazole derivatives, with inhibitory activity against monoamine oxidases (MAO) type A and B, was accomplished using polysaccharide‐based chiral stationary phases (CSPs: Chiralpak AD, Chiralcel OD, and Chiralcel OJ). Pure alcohols, such as ethanol and 2‐propanol, and typical normal‐phase binary mixtures, such as n‐hexane and alcohol modifier, were used as mobile phases. Single enantiomers of several analytes examinated were isolated on a semipreparative scale, and their chiroptical properties were measured. The assignment of the absolute configuration was established for one compound by single‐crystal X‐ray diffraction method and for the other three by CD spectroscopy. The inhibitory activity against MAO of racemic samples and single enantiomers were evaluated in vitro. Chirality 16:625–636, 2004. © 2004 Wiley‐Liss, Inc.
Morbidity and mortality of colorectal carcinoma surgery differs by insurance status
Authors: Kelz Rachel Rapaport , Gimotty Phyllis A. , Polsky Daniel , Norman Sandra , Fraker Douglas , DeMichele Angela 
Published: September 2004

AbstractBACKGROUNDUninsured and underinsured patients are reported to be at an increased risk for impaired access to healthcare, delayed medical treatment, and the receipt of substandard care. These differences in care may result in disparities in surgical outcomes among patients with different types of insurance. In the current study, the authors examined associations between the insurance provider and short‐term surgical outcomes after surgery for colorectal carcinoma and evaluated the extent to which two risk factors (comorbid disease and admission type) might explain any observed association.METHODSThe authors conducted a nationally representative retrospective cohort study of 13,415 adults ages 40–64 years who were admitted for surgery for colorectal carcinoma to hospitals that participated in the Agency for Healthcare Research and Quality Healthcare Cost and Utilization Project National Inpatient Sample, releases 6 and 7, in 1997 and 1998. Multivariate logistic regression models were developed to describe the correlations between insurance status and the risks of a postoperative complication or postoperative death after adjustment for socioeconomic factors, comorbid conditions, and admission type.RESULTSUninsured and Medicaid patients were found to have more emergent admissions and more comorbid disease compared with patients with private health insurance. Patients without private health insurance had higher rates of postoperative complications and in‐hospital death compared with those patients with private insurance. After adjusting for patient and hospital characteristics, patients with Medicaid were found to be 22% more likely to develop a complication during their hospital admission (odds ratio [OR] of 1.22; 95% confidence interval [95%CI], 1.06–1.40) and 57% more likely to die postoperatively (OR of 1.57; 95% CI, 1.01–2.42) compared with patients with private insurance.CONCLUSIONSThe current study findings suggest that the uninsured and Medicaid populations are at greater risk of developing postoperative complications and dying than the privately insured population due only in part to preexisting medical comorbidities and emergent admission type. Cancer 2004. © 2004 American Cancer Society.
Autoregulation of the N‐myc gene is operative in neuroblastoma and involves histone deacetylase 2
Authors: Kim Marianne K. H. , Carroll William L. 
Published: September 2004

AbstractBACKGROUNDAutoregulation of the myc gene family is a negative feedback mechanism known to occur at high levels of Myc expression. Loss of this mechanism and associated Myc overexpression has been observed in human tumors, thereby contributing to tumorigenesis. The childhood tumor neuroblastoma is characterized by N‐myc amplification in aggressive and highly proliferative tumors that occur in a subset of patients. The precise molecular mechanism of autoregulation is unknown, and previous observations indicated that N‐myc autoregulation was intact only in single‐copy neuroblastoma cell lines.METHODSTransient reporter assays and trichostatin A (TSA) experiments were performed to evaluate several candidate genes, including Mxi1, c‐myc promoter binding protein 1 (MBP‐1), Miz, and histone deacetylase 2 (HDAC2), for their involvement in N‐myc autoregulation. Mxi1 and HDAC2 were examined further for their expression levels and effects on endogenous N‐myc levels. Finally, their recruitments to the N‐myc promoter were investigated by chromatin immunoprecipitation (ChIP).RESULTSThe autoregulatory circuit was operative, even in amplified cell lines. Mxi1 consistently showed a modest effect in down‐regulating N‐myc in transient reporter assays. Overexpression of the c‐myc, Mxi1, and mHDAC2 genes resulted in a threefold to fourfold decrease in endogenous N‐myc levels. Mxi1 and HDAC2 were up‐regulated by N‐Myc in an myc‐inducible cell line and in N‐myc‐expressing cell lines. In addition, down‐regulation of the N‐myc promoter was relieved in the presence of TSA. Increased association of HDAC2 with the autoregulatory region within the N‐myc promoter by ChIP was observed upon down‐regulation of endogenous N‐myc.CONCLUSIONSThe autoregulatory circuit was intact in both amplified and single‐copy neuroblastoma cell lines. Furthermore, myc gene autoregulation occurred through histone deacetylation. Cancer 2004. © 2004 American Cancer Society.
Class I and class II ganglion cells of rabbit retina: A structural basis for X and Y (brisk) cells
Authors: Famiglietti Edward V. 
Published: September 2004

AbstractMorphological studies of rabbit retina have identified ganglion cells resembling “alpha” cells but none resembling cat “beta” cells. Four distinct types of class I cell, similar to alpha cells, were identified, each narrowly stratified and differing from the other three principally in the level of dendritic branching. These four levels of dendritic branching flank the two starburst/cholinergic amacrine cell substrata that mark the middle of sublaminae a and b. Compared with the other three, class Ia2 cells are the largest in cell body and dendritic field size, are sometimes homotypically dye coupled, and have slightly broader dendritic stratification. Class Ia2 and the slightly smaller class Ib2 cells form a paramorphic pair. Compared with class I cells, class II cells have smaller dendritic fields; a greater tendency to “tufted” dendritic branching, as shown in the companion paper; branching at one of three levels of the IPL; and similarly narrow stratification. Class IIa and class Ia1 cells branch at the same level, as do class IIb1 and class Ib1 cells. Class IIb2 cells branch slightly nearer the ganglion cell layer than class Ib2 cells and costratify with “blue‐ON” cone bipolar cells. The class IIa and IIb2 cells form a paramorphic pair, whereas class IIb1 cells appear to be unpaired. The four types of class I cell probably correspond to ON‐ and OFF‐center brisk‐transient, fast‐movement and slow‐movement cells, whereas the three types of class II cell probably correspond to ON‐ and OFF‐center brisk‐sustained and color‐coded ON‐center X cells. J. Comp. Neurol. 478:323–346, 2004. © 2004 Wiley‐Liss, Inc.
Distribution of transcription factor inducible cyclicAMP early repressor (ICER) in rodent brain and pituitary
Authors: Kell Christian A. , Dehghani Faramarz , Wicht Helmut , Molina Carlos A. , Korf Horst‐Werner , Stehle Jörg H. 
Published: September 2004

AbstractIn morphogenetic dynamics of neurons, and in adaptive physiology of brain function, transcription factors of the cyclicAMP signaling pathway, such as activator cyclicAMP responsive element binding protein (CREB) and inhibitor inducible cyclicAMP early repressor (ICER), play an important role. In particular, the presence of the transcription factor ICER in neurons or neuroendocrine cells suggests the need for the gating of an up‐regulated gene expression. Little is known, however, about the natural distribution of the inhibitory transcription factor ICER. We, therefore, mapped the rodent brain and pituitary for an ICER immunoreaction and found a nuclear staining for this transcription factor. ICER‐positive glial cells were found throughout the brain. ICER‐positive neurons were found in sensory input centers, like the olfactory bulb, or sensory brain stem nuclei, and in hypothalamic nuclei involved in central neuroendocrine control. In addition, neuroendocrine/endocrine transducers, like the pituitary and the pineal gland showed a high basal presence of ICER. Our data show that a basic ICER level is required by many cell systems and can be seen as an anticipatory and/or a protective measure in systems with superior reactive dynamics. J. Comp. Neurol. 478:379–394, 2004. © 2004 Wiley‐Liss, Inc.
Synaptic and extrasynaptic localization of brain‐derived neurotrophic factor and the tyrosine kinase B receptor in cultured hippocampal neurons
Authors: Swanwick Catherine Croft , Harrison Madaline B. , Kapur Jaideep 
Published: September 2004

AbstractBrain‐derived neurotrophic factor (BDNF) regulates synapses, but the distribution of BDNF and its receptor TrkB relative to the location of glutamatergic and γ‐aminobutyric acidergic (GABAergic) synapses is presently unknown. Immunocytochemistry was performed in primary hippocampal neuron cultures to determine whether BDNF and TrkB are preferentially localized to excitatory or inhibitory markers at 7, 14, and 21 days in vitro (DIV). Glutamatergic sites were localized with vesicular glutamate transporter type 1 (VGLUT1) as presynaptic marker and the NR1 subunit of the NMDA receptor and the GluR1 subunit of the AMPA receptor as receptor markers. GABAergic sites were labeled with the 65‐kDa isoform of glutamic acid decarboxylase (GAD‐65) as presynaptic marker and the γ2 subunit of the GABAA receptor as receptor marker. During development, <30% of BDNF punctae and TrkB clusters were localized to glutamatergic and GABAergic markers. Because their rates of colocalization did not change from 7 to 21 DIV, this study details the distribution of BDNF and TrkB at 14 DIV. BDNF was preferentially colocalized with glutamatergic markers VGLUT1 and NR1 (∼30% each). TrkB was also relatively highly colocalized with VGLUT1 and NR1 (∼20% each) but was additionally highly colocalized with GABAergic markers GAD‐65 (∼20%) and γ2 (∼30%). NR1 clusters colocalized with BDNF puncta and TrkB clusters were mostly extrasynaptic, as were γ2 clusters colocalized with TrkB clusters. These results show that, whereas most BDNF and TrkB protein is extrasynaptic, BDNF is preferentially associated with excitatory markers and that TrkB is associated equally with excitatory and inhibitory markers. J. Comp. Neurol. 478:405–417, 2004. © 2004 Wiley‐Liss, Inc.
Variable effects of chronic subcutaneous administration of rotenone on striatal histology
Authors: Zhu Chunni , Vourc'h Patrick , Fernagut Pierre‐Olivier , Fleming Sheila M. , Lacan Sanja , Dicarlo Cheryl D. , Seaman Ronald L. , Chesselet Marie‐Françoise 
Published: September 2004

AbstractWhen infused in rats, rotenone, a mitochondrial complex I inhibitor, induces alterations that resemble the histological changes of Parkinson's disease, particularly degeneration of the nigrostriatal dopaminergic system. However, the specificity of rotenone effects has been challenged recently. We have re‐examined the alterations caused by rotenone in the substantia nigra and the striatum of rats after infusion of rotenone (2 mg/kg per day s.c.) for 21 days. Three patterns of striatal tyrosine‐hydroxylase immunoreactivity (TH‐IR) were observed: 46% of animals showed no reduction, and 46% of animals showed diffuse reduction in TH‐IR, whereas one animal presented a focal loss of TH‐IR in the striatum. Confocal microscopy analysis showed that the vesicular monoamine transporter (VMAT2) was decreased in parallel with TH‐IR, strongly suggesting a loss of striatal DA nerve terminals in animals with diffuse or central TH‐IR loss. However, no significant loss of TH‐IR neurons was observed in the substantia nigra. Analysis of NeuN and DARPP‐32 immunoreactivity, and Nissl staining, in the striatum showed no striatal neuronal loss in animals with either preserved TH‐IR or diffuse TH‐IR reduction. However, in the animal with focal TH‐IR loss, severe neuronal loss was evident in the center and the periphery of the striatum, together with microglial activation detected by OX‐6 and OX‐42 staining. Thus, in most cases, chronic subcutaneous infusion of low doses of rotenone does not induce significant striatal neuronal loss, despite TH‐IR and VMAT‐IR reduction in a subset of animals, supporting the use of rotenone as a model of Parkinson's disease under carefully controlled experimental conditions. J. Comp. Neurol. 478:418–426, 2004. © 2004 Wiley‐Liss, Inc.