Distribution by Scientific Domains

Selected Abstracts

Physics, Chemistry and Applications of the AC Diaphragm Discharge and Related Discharges in Electrolyte Solutions

A. I. Maximov
Abstract Three types of the underwater discharges produced by means of AC voltage sources (500-2000 V, 0.05-1 A) were investigated. Dynamic volt-ampere characteristics and radiation intensity of these discharges were measured. It was observed the optical afterglow time up to 0.1-0.2 s. The information about their chemical action was got by stimulation of the oxidation of the organic and inorganic substances. It was found that the treatment of the cellulose and the flax by means of the underwater discharges results in the change of their molecular mass, lignin contain and surface concentration of the oxygen containing functional groups. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Crystal structures and spectroscopic characterization of chiral and racemic 4-phenyl-1,3-oxazolidin-2-one

S. Kitoh
Abstract Crystal structures of (R)- and (rac)-4-phenyl-1,3-oxazolidin-2-one (4-POO) have been determined by X-ray diffraction and characterized by the solid state 13C NMR and IR spectra. Molecular geometries and intermolecular interactions in (R)- and (rac)-4-POO crystals are very similar to each other; 4-POO molecules are linked via the N-H,O intermolecular hydrogen bonds to form the chained structure. Chemical shifts of the solid state 13C NMR spectra are very similar to each other, whereas the 1H spin-lattice relaxation times (T1H) value for (R)-4-POO is five times as large as that for (rac)-4-POO, reflecting the more restricted mobility of the (R)-4-POO chain. Although both crystals contain an unique molecule in the asymmetric unit, a doublet feature is observed for the C=O stretching mode in the IR spectra of (R)- and (rac)-4-POO crystals. The frequency gap of the C=O bands are correlated with the strength of the dipole-dipole interactions between the neighboring C=O groups. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [source]

Rosiglitazone combined with insulin preserves islet , cell function in adult-onset latent autoimmune diabetes (LADA)

Zhiguang Zhou
Abstract Background LADA is thought to result from the chronic autoimmune destruction of the insulin-producing pancreatic , cells. In addition to antidiabetic effects, the newly developed insulin sensitizer-thiazolidinediones have the potential to increase the insulin content of islet cells by downregulating local inflammation and autoimmune response. Therefore, we hypothesized that LADA patients might benefit from thiazolidinediones treatment. Methods LADA patients, with a fasting C-peptide (FCP) of 0.3 nmol/L or more, were enrolled and randomly assigned to receive subcutaneous insulin alone (insulin group, n = 12) or rosiglitazone plus insulin (insulin + RSG group, n = 11) to compare the impacts on islet , cell function. Plasma glucose, HbA 1c, fasting C-peptide (FCP) and C-peptide after 2 h 75-g glucose load (PCP) were determined every 6 months. GAD-Ab and C-peptide were measured with radioimmune assays. Islet , cell function was evaluated by PCP and ,CP(,CP = PCP-FCP). Results All of the 23 patients have been followed up for 6 months, 17 cases for 12 months and 14 for 18 months. (1) During 6 months' follow-up, there were no significant changes for ,CP and PCP levels in both groups. (2) PCP and ,CP levels in insulin + RSG group patients stayed steady during the 12 months' observation (P = 0.161 for both PCP and ,CP), while in the insulin alone group, both FCP (P = 0.021) and PCP (P = 0.028) levels decreased significantly. Furthermore, PCP (P = 0.004) and ,CP(P = 0.015) differences between 12th month and baseline were higher in insulin + RSG group than those in the insulin group. (3) When observed up to 18 months, PCP and ,CP levels in insulin + RSG group patients still stayed steady, while PCP and ,CP levels decreased more in the insulin alone group. Conclusions This pilot study suggests that rosiglitazone combined with insulin may preserve islet , cell function in LADA patients. Copyright © 2004 John Wiley & Sons, Ltd. [source]

J -Based Analysis and DFT,NMR Assignments of Natural Complex Molecules: Application to 3,,7-Dihydroxy-5,6-epoxycholestanes

Jesús Javier Poza
Abstract In order to reproduce the stereochemical dispositions of the epoxy and hydroxy functionalities, four 3,,7-hydroxy-5,6-epoxycholestanes were easily prepared from cholesterol, and their NMR spectroscopic data were experimentally obtained from 1D and 2D NMR experiments. An exhaustive QM- J -based analysis was then performed to replicate the experimental H,H and C,H coupling constants as well as the 13C NMR chemical shifts. The B3LYP GIAO methodology with the 6-311-G(d,p) basis set was chosen and showed that the data obtained from rings A and B were sufficient to calculate the correct stereochemistry of the 5,6-epoxy and 7-hydroxy groups. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

A New and Productive Route to 1-Heteroarylcyclopropanols

Vladimir N. Belov
Abstract (E/Z)-2-(1-Allyloxycyclopropyl)-3-methoxyacrylonitrile (4 -All) was designed and prepared in five steps (58% overall yield) from ethyl cyclopropylidenacetate as a valuable precursor to various 1-heteroarylcyclopropanols. Its condensation with amidines, guanidine, hydrazine, and methyl thioglycolate and subsequent removal of the allyl protecting group yields 1-heteroarylcyclopropanols such as 1 -OH (36% over 2 steps), a very potent NO-independent stimulator of soluble guanylate cyclase. Direct cleavage of the allyl ether protecting group [by palladium-catalyzed substitution with lithium p -toluenesulfinate in AcOH or treatment with c -HexMgBr/Ti(OiPr)4] gives highly functionalized, sterically congested 1-heteroarylcyclopropanols 29, 30, and 34 with intact amino and ester groups. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Doubling in Size, Post-Merger, SBC Learned To Consolidate Functions Quickly and Effectively

Joy Rick
Global telecom giant SBC has gotten so big through acquisitions. And, by experience, they have learned the critical systems and processes to whip into operation to make the blend a success. Recognizing the link between business success and strict attention to human resources issues, SBC has formalized guidelines for managers to use throughout the transition process, fostered open communication of change, and determinedly intermingled work groups. © 2001 John Wiley & Sons, Inc. [source]

Synthesis and spectral studies of diorganotin heterocyclic dithiocarbamate complexes and crystal structures of (2- F -Bz)2Sn(Cl) S2CN(CH2CH2)2NEt and (3- Cl -Bz)2Sn [S2CN(CH2CH2)2NEt]2 , 0.5HN(CH2CH2)2NH

Shengcai Xue
Some new diorganotin(IV) complexes of heterocyclic dithiocarbamate having general formula R2Sn(Cl)S2CNR'2 and R2Sn(S2CNR'2)2 [R = 2-F-Bz, 3-Cl-Bz; NR'2 = N(CH2CH2)2NMe, N(CH2CH2)2NEt, and N(CH2CH2)2NBz] have been prepared, respectively. Elemental analyses, IR, and NMR spectral data characterized all compounds. The crystal structures of (2-F-Bz)2Sn(Cl)S2CN(CH2CH2)2NEt 2 and (3-Cl-Bz)2Sn[S2CN(CH2CH2)2NEt]2 , 0.5 HN(CH2CH2)2NH 5 were determined by single crystal X-ray diffractometer. In the crystal of complex 2, the tin atom is rendered five-coordination in a trigonal bipyramidal configuration by coordinating with S atoms of dithiocarbamate groups. For complex 5, the central Sn atom exists in a skew-trapezoidal planar geometry defined by two asymmetrically coordinated dithiocarbamate ligands and two 3-chlorobenzyl groups. © 2005 Wiley Periodicals, Inc. 16:271,277, 2005; Published online in Wiley InterScience ( DOI 10.1002/hc.20096 [source]

Mother,infant behavioral interactions in teenage and adult mothers during the first six months postpartum: Relations with infant development

Andrée Pomerleau
The purpose of this study was to compare adolescent mothers' (high-risk group), at-risk adult mothers' (moderate-risk group), and no-risk adult mothers' (low-risk group) behavioral interactions at one and six months postpartum, and to examine the relationships between maternal behaviors and infant developmental scores on the Bayley scales. Results indicated that high-risk teenage mothers and moderate-risk adult mothers vocalized less and had lower contingency rating scores compared to low-risk adult mothers. Also, infants in the high-risk and moderate-risk groups obtained lower mental scores at six months compared to the low-risk group. Moderate stability across time was found for maternal vocalizations and infant scores on the mental scale. Maternal vocalizations and behavioral contingency rating scores at one month were associated with infants' six-month performance on the Bayley scales. Specific intervention strategies were discussed with the aim of targeting and improving early maternal behavioral patterns in at-risk groups. ©2003 Michigan Association for Infant Mental Health. [source]

Attachment, culture, and the caregiving system: The cultural patterning of everyday experiences among Anglo and Puerto Rican mother,infant pairs

Vivian J. Carlson
This investigation focuses on cultural differences in the relationship between maternal sensitivity, emotional expression, and control strategies during the first year of life and infant attachment outcomes at 12 months. Participants were middle-class Puerto Rican and Anglo mother,infant pairs (N = 60). Ratings of physical control, emotional expression, and maternal sensitivity during mother,infant interactions in five everyday home settings, videotaped when the infants were 4, 8, and 12 months old, were examined in combination with 12-month Strange Situation classifications. Results suggest that physical control shows a different pattern of relatedness to maternal sensitivity, emotional expression, and attachment outcomes among the Puerto Rican compared to the Anglo mothers in this study. These findings have implications for practitioners and researchers interested in normative parenting among diverse cultural groups. ©2003 Michigan Association for Infant Mental Health. [source]

Germline mutations 657del5 of the NBS1 gene contribute significantly to the incidence of breast cancer in Central Poland

Jan Steffen
Abstract Recent studies have demonstrated that heterozygous carriers of the NBS1 657del5 mutation have an increased risk for familial and bilateral breast cancer, but similar studies in consecutive breast cancer patients were inconclusive. Here, in a study of 562 nonselected breast cancer patients from Central Poland, we found 11 (1.96%) 657del5 mutation carriers vs. 3.47 expected (OR 3.21, 95%CI: 1.36,7.61, p = 0.0107) and only 9 (1.6%) carriers of the 5382insC mutation of the BRCA1 gene, most frequently found among breast cancer patients in Poland. No carriers of R215W, another pathogenic mutation of the NBS1 gene, were found in the present study. All carriers of the 657del5 mutation had sporadic breast tumors while 5 of 9 5382insC carriers had a family history of breast/ovarian cancer or bilateral breast carcinoma. In the pooled group of patients from the present and our previous study, carried out also in patients from Central Poland, we obtained the following risk estimates (OR) for 657del5 carriers, as related to the age at breast cancer diagnosis: <40 years: 8.36; (95%CI: 2.57,27.27) p = 0.0003; <50 years: 4.27 (95%CI: 1.67,10.89) p = 0.003; ,50 years: 2.40 (95%CI: 0.91,6.35) p = 0.1250; all ages: 3.13 (95% CI: 1.40,7.00) p = 0.0066. These findings demonstrate conclusively that NBS1 657del5 mutation carriers have a significantly, though moderately increased, age-related risk of breast cancer, and imply that in populations with a high 657del5 carrier frequency this mutation may contribute substantially to the overall incidence of breast cancer, particularly in younger age groups. © 2006 Wiley-Liss, Inc. [source]

Epidemiology of binge eating disorder

Ruth H. Striegel-Moore
Abstract Objective First described over 50 years ago, binge eating disorder (BED) only recently has become the focus of epidemiologic studies. This article provides a comprehensive review of these studies. Method Relevant studies were examined and summarized in the form of a narrative review. Results Similar to the early studies of bulimia nervosa (BN), the first generation of epidemiologic studies of BED is limited in scope or methodology. They focus on prevalence rates and provide only basic demographic characteristics and often use less than optimal sampling or assessment methods. Discussion Results suggest that the demographic profile of BED may be more diverse than that of BN. Future studies should evaluate complex etiologic models in representative samples that include men and a broader range of ethnic minority groups. © 2003 by Wiley Perodicals, Inc. Int J Eat Disord 34: S19,S29, 2003. [source]

Gastropods on Submersed Macrophytes in Yangtze Lakes: Community Characteristics and Empirical Modelling

Hai-Jun Wang
Abstract Epiphytic gastropods in Yangtze lakes have suffered from large-scale declines of submersed macrophytes during past decades. To better understand what controls gastropod community, monthly investigations were carried out in four Yangtze lakes during December, 2001,March, 2003. Composed of 23 species belonging to Pulmonata and Prosobranchia, the community is characterized by the constitution of small individuals. The average density and biomass were 417 ± 160 ind/m2 and 18.05 ± 7.43 g/m2, with maxima around August. Submersed macrophyte biomass is shown to be the key factor affecting species number, density, and biomass of gastropods. Accordingly, a series of annual and seasonal models yielding high predictive powers were generated. Preference analyses demonstrated that pulmonates and prosobranchs with different respiratory organs prefer different macrophyte functional groups. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The Role of Benzodiazepines in the Treatment of Insomnia

Meta-Analysis of Benzodiazepine Use in the Treatment of Insomnia
PURPOSE: To obtain a precise estimate of the efficacy and common adverse effects of benzodiazepines for the treatment of insomnia compared with those of placebo and other treatments. BACKGROUND: Insomnia, also referred to as disorder of initiating or maintaining sleep, is a common problem and its prevalence among older people is estimated to be 23% to 34%.1 The total direct cost in the United States for insomnia in 1995 was estimated to be $13.9 billion.2 The complaint of insomnia in older people is associated with chronic medical conditions; psychiatric problems, mainly depression, chronic pain, and poor perceived general condition;1,3,4 and use of sleep medications.5 Thus in most cases, insomnia is due to some other underlying problem and is not just a consequence of aging.6 Accordingly, the management of insomnia should focus on addressing the primary problem and not just short-term treatment of the insomnia. Benzodiazepines belong to the drug class of choice for the symptomatic treatment of primary insomnia.7 This abstract will appraise a meta-analysis that compared the effect of benzodiazepines for short-term treatment of primary insomnia with placebo or other treatment. DATA SOURCES: Data sources included articles listed in Medline from 1966 to December 1998 and the Cochrane Controlled Trials Registry. The medical subject heading (MeSH) search terms used were "benzodiazepine" (exploded) or "benzodiazepine tranquillizers" (exploded) or "clonazepam,""drug therapy,""randomized controlled trial" or "random allocation" or "all random,""human," and "English language." In addition, bibliographies of retrieved articles were scanned for additional articles and manufacturers of brand-name benzodiazepines were asked for reports of early trials not published in the literature. STUDY SELECTION CRITERIA: Reports of randomized controlled trials of benzodiazepine therapy for primary insomnia were considered for the meta-analysis if they compared a benzodiazepine with a placebo or an alternative active drug. DATA EXTRACTION: Data were abstracted from 45 randomized controlled trials representing 2,672 patients, 47% of whom were women. Fifteen studies included patients age 65 and older and four studies involved exclusively older patients. Twenty-five studies were based in the community and nine involved inpatients. The duration of the studies ranged from 1 day to 6 weeks, with a mean of 12.2 days and median of 7.5 days. The primary outcome measures analyzed were sleep latency and total sleep duration after a sleep study, subjects' estimates of sleep latency and sleep duration, and subjects' report of adverse effects. Interrater reliability was checked through duplicate, independent abstraction of the first 21 articles. Overall agreement was between 95% and 98% (kappa value of 0.90 and 0.95 accordingly) for classification of the studies and validity of therapy, and 76% (kappa value of 0.51) for study of harmful effects. A scale of 0 to 5 was used to rate the individual reports, taking into account the quality of randomization, blinding, follow-up, and control for baseline differences between groups. Tests for homogeneity were applied across the individual studies and, when studies were found to be heterogeneous, subgroup analysis according to a predefined group was performed. MAIN RESULTS: The drugs used in the meta-analysis included triazolam in 16 studies; flurazepam in 14 studies; temazepam in 13 studies; midazolam in five studies; nitrazepam in four studies; and estazolam, lorazepam, and diazepam in two studies each. Alternative drug therapies included zopiclone in 13 studies and diphenhydramine, glutethimide, and promethazine in one study each. Only one article reported on a nonpharmacological treatment (behavioral therapy). The mean age of patients was reported in 33 of the 45 studies and ranged between 29 and 82. SLEEP LATENCY: In four studies involving 159 subjects, there was sleep-record latency (time to fall asleep) data for analysis. The pooled difference indicated that the latency to sleep for patients receiving a benzodiazepine was 4.2 minutes (95% CI = (,0.7) (,9.2)) shorter than for those receiving placebo. Patient's estimates of sleep latency examined in eight studies showed a difference of 14.3 minutes (95% CI = 10.6,18.0) in favor of benzodiazepines over placebo. TOTAL SLEEP DURATION: Analysis of two studies involving 35 patients in which total sleep duration using sleep-record results was compared indicated that patients in the benzodiazepine groups slept for an average of 61.8 minutes (95% CI = 37.4,86.2) longer than those in the placebo groups. Patient's estimates of sleep duration from eight studies (566 points) showed total sleep duration to be 48.4 minutes (95% CI = 39.6,57.1) longer for patients taking benzodiazepines than for those on placebo. ADVERSE EFFECTS: Analysis of eight studies (889 subjects) showed that those in the benzodiazepine groups were more likely than those in the placebo groups to complain of daytime drowsiness (odds ratio (OR) 2.4, 95% confidence interval (CI) = 1.8,3.4). Analysis of four studies (326 subjects) also showed that subjects in the benzodiazepine groups were more likely to complain of dizziness or lightheadedness than the placebo groups. (OR 2.6, 95% CI = 0.7,10.3). Despite the increased reported side effects in the benzodiazepine groups, drop-out rates were similar in the benzodiazepine and placebo groups. For patient reported outcome, there was no strong correlation found for sleep latency data, (r = 0.4, 95% CI = (,0.3) (,0.9)) or for sleep duration (r = 0.2, 95% CI = ,0.8,0.4) between benzodiazepine dose and outcome. COMPARISON WITH OTHER DRUGS AND TREATMENTS: In three trials with 96 subjects, meta-analysis of the results comparing benzodiazepines with zopiclone, did not show significant difference in sleep latency in the benzodiazepine and placebo groups, but the benzodiazepine groups had increased total sleep duration (23.1 min. 95% CI = 5.6,40.6). In four trials with 252 subjects, the side effect profile did not show a statistically significant difference (OR 1.5, CI 0.8,2.9). There was only one study comparing the effect of behavioral therapy with triazolam. The result showed that triazolam was more effective than behavioral therapy in decreasing sleep latency, but its efficacy declined by the second week of treatment. Behavioral therapy remained effective throughout the 9-week follow-up period. There were four small trials that involved older patients exclusively, with three of the studies having less than 2 weeks of follow-up. The results were mixed regarding benefits and adverse effects were poorly reported. CONCLUSION: The result of the meta-analysis shows that the use of benzodiazepines results in a decrease in sleep latency and a significant increase in total sleep time as compared with placebo. There was also a report of significantly increased side effects, but this did not result in increased discontinuation rate. There was no dose-response relationship for beneficial effect seen with the use of benzodiazepines, although the data are scant. Zopiclone was the only alternative pharmacological therapy that could be studied with any precision. There was no significant difference in the outcome when benzodiazepines were compared with zopiclone. There was only one study that compared the effect of benzodiazepines with nonpharmacological therapy; thus available data are insufficient to comment. [source]

Psychotherapy in Brunei Darussalam

N. Kumaraswamy
Clinical psychologists face unique challenges in developing Southeast Asian countries because mental health care has not received the kind of attention it deserves. In part, this has been the result of lack of knowledge or misunderstanding about mental health and adherence to various religious and traditional beliefs. In this article, the practice of psychotherapy in Brunei Darussalam is reviewed and then illustrated with a typical case, Mrs. A Asian psychotherapists need more comprehensive knowledge of prevailing cultural beliefs and religious practices among multiethnic population groups. © 2007 Wiley Periodicals, Inc. J Clin Psychol: In Session 63: 735,744, 2007. [source]

Culturally centered psychosocial interventions

Guillermo Bernal
Over the last few decades, psychologists and other health professionals have called attention to the importance of considering cultural and ethnicminority aspects in any psychosocial interventions. Although, at present, there are published guidelines on the practice of culturally competent psychology, there is still a lack of practical information about how to carry out appropriate interventions with specific populations of different cultural and ethnic backgrounds. In this article, the authors review relevant literature concerning the consideration of cultural issues in psychosocial interventions. They present arguments in favor of culturally centering interventions. In addition, they discuss a culturally sensitive framework that has shown to be effective for working with Latinos and Latinas. This framework may also be applicable to other cultural and ethnic groups. @ 2006 Wiley Periodicals, Inc. [source]

MOPED: Method for optimizing physical energy parameters using decoys

Chaok Seok
Abstract We present a method called MOPED for optimizing energetic and structural parameters in computational models, including all-atom energy functions, when native structures and decoys are given. The present method goes beyond previous approaches in treating energy functions that are nonlinear in the parameters and continuous in the degrees of freedom. We illustrate the method by improving solvation parameters in the energy function EEF1, which consists of the CHARMM19 polar hydrogen force field augmented by a Gaussian solvation term. Although the published parameters for EEF1 correctly discriminate the native from decoys in the decoy sets of Levitt et al., they fail on several of the more difficult decoy sets of Baker et al. MOPED successfully finds improved parameters that allow EEF1 to discriminate native from decoy structures on all protein structures that do not have metals or prosthetic groups. © 2002 Wiley Periodicals, Inc. J Comput Chem 24: 89,97, 2003 [source]

An improved OPLS,AA force field for carbohydrates

D. Kony
Abstract This work describes an improved version of the original OPLS,all atom (OPLS,AA) force field for carbohydrates (Damm et al., J Comp Chem 1997, 18, 1955). The improvement is achieved by applying additional scaling factors for the electrostatic interactions between 1,5- and 1,6-interactions. This new model is tested first for improving the conformational energetics of 1,2-ethanediol, the smallest polyol. With a 1,5-scaling factor of 1.25 the force field calculated relative energies are in excellent agreement with the ab initio -derived data. Applying the new 1,5-scaling makes it also necessary to use a 1,6-scaling factor for the interactions between the C4 and C6 atoms in hexopyranoses. After torsional parameter fitting, this improves the conformational energetics in comparison to the OPLS,AA force field. The set of hexopyranoses included in the torsional parameter derivation consists of the two anomers of D -glucose, D -mannose, and D -galactose, as well as of the methyl-pyranosides of D -glucose, D -mannose. Rotational profiles for the rotation of the exocyclic group and of different hydroxyl groups are also compared for the two force fields and at the ab initio level of theory. The new force field reduces the overly high barriers calculated using the OPLS,AA force field. This leads to better sampling, which was shown to produce more realistic conformational behavior for hexopyranoses in liquid simulation. From 10-ns molecular dynamics (MD) simulations of ,- D -glucose and ,- D -galactose the ratios for the three different conformations of the hydroxymethylene group and the average 3JH,H coupling constants are derived and compared to experimental values. The results obtained for OPLS,AA,SEI force field are in good agreement with experiment whereas the properties derived for the OPLS,AA force field suffer from sampling problems. The undertaken investigations show that the newly derived OPLS,AA,SEI force field will allow simulating larger carbohydrates or polysaccharides with improved sampling of the hydroxyl groups. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1416,1429, 2002 [source]

Analyses of consumers' dietary behavior: An application of the AIDS model to supermarket scanner data

Eugene Jones
Nationwide food consumption surveys often find no difference in the diets of lower and higher income Americans, while studies of particular food commodities find major differences. These contrasting results represent a consumption paradox. We attempt to gain an understanding of this paradox by using supermarket scanner data to examine food purchases and, by extension, consumption patterns for consumers in two, geographically distinct, income areas. These areas are part of the larger Columbus, OH, metropolitan area (CMA) and six stores are selected for purchase and consumption analyses,three from the lowest income areas of the CMA and three from the highest income areas. Seven product categories are analyzed in this study and these categories are subdivided into meaningful nutritional classes. An Almost Ideal Demand System is employed and the empirical results reveal major differences in consumption behavior for the two groups. [EconLit citations: D120 and D190.] © 2003 Wiley Periodicals, Inc. Agribusiness 19: 203,221, 2003. [source]

An algebraic characterization of projective-planar graphs

Lowell Abrams
Abstract We give a detailed algebraic characterization of when a graph G can be imbedded in the projective plane. The characterization is in terms of the existence of a dual graph G* on the same edge set as G, which satisfies algebraic conditions inspired by homology groups and intersection products in homology groups. © 2003 Wiley Periodicals, Inc. J Graph Theory 42: 320,331, 2003 [source]

The role of the cyclic imide in alternate degradation pathways for asparagine-containing peptides and proteins

Michael P. DeHart
Abstract Peptides and proteins exhibit enhanced reactivity at asparagine residues due to the formation of a reactive succinimide intermediate that produces normal and isoaspartyl deamidation products along with significant racemization. This study examines the potential for attack of amine nucleophiles at the succinimide carbonyls to generate alternate decomposition products, depending on the nucleophile involved in the reaction. The reactions of the model peptides Phe-Asn-Gly (FNG) and Phe-isoAsn-Gly (FisoNG) were explored as a function of pH (8.5,10.5) in the presence and absence of ammonia buffer (0.2,2 M) using an isocratic HPLC method to monitor reactant disappearance and product formation. In addition to deamidation to form isoAsp and Asp peptides, two additional types of reactions were found to occur via the succinimide intermediate under these conditions. Back-reaction of the succinimide with ammonia led to peptide backbone isomerization while intramolecular attack by the amino terminus produced diketopiperazines. A kinetic model assuming a central role for the succinimide intermediate was derived to fit the concentration versus time data. These studies implicate the cyclic imide as a key intermediate in the formation of alternate peptide and protein degradants, including possible covalent amide-linked aggregates that may form from intermolecular attack of the cyclic imide by neighboring amino groups. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 2667,2685, 2007 [source]

Genetic and Pathogenic Variation Among Tobacco Black Shank Strains of Phytophthora parasitica var. nicotianae from the Main Tobacco Growing in China

X. G. Zhang
Abstract Pathogenic and genetic variability among seven populations of Phytophthora parasitica var. nicotianae from individual tobacco fields (Yunnan, Shandong, Henan, Heilongjiang, Shanxi, Fujian and Sichuan provinces) were investigated using pathogenicity and randomly amplified polymorphic DNA (RAPD) analyses; 63 strains were isolated from different fields of seven tobacco growing regions, using tobacco cv. Hongda as a baiting host. Pathogenic variability was evaluated in greenhouse studies using five tobacco cultivars that have different levels of resistance to tobacco black shank; 75 and 73% of the strains were pathogenic on M3 and M4, 29 and 33% on M1 and M2, and 94% were pathogenic on M5, respectively. Disease severity incited by different strains varied significantly on individual tobacco cultivars. The percentage of strains pathogenic on different cultivars varied among locations. Genotypic variation among 63 strains was evaluated by RAPD analysis. Ten primers detected 89 polymorphic bands. Cluster and principal coordinates analysed cluster groups. the minor group contained 26 strains, and major group contained 37 strains. Estimates of genetic diversity based on RAPD analysis ranged from 0.24 to 0.34 within populations to 0.36 among all strains from all populations. Phytophthora parasitica var. nicotianae populations were genotypically and phenotypically variable, but no distinct genotypic differences were identified among populations from the seven locations. [source]

Synthesis of glyco-microspheres via a thiol-ene coupling reaction

Wenfang Gu
Thiol-ene click chemistry was employed to form microspheres with sugar groups with high bioactivity and efficient binding of Concanavalin A. Two systems were investigated , a microsphere prepared from ethyleneglycol dimethacrylate, which contained excess vinyl functionalities as a natural result of the preparation process, and the commercially available Wang microsphere, which had to be modified with acryloylchloride to generate pendant vinyl groups. [Color figure can be viewed in the online issue, which is available at] [source]

Preparation of novel acrylamide-based thermoresponsive polymer analogues and their application as thermoresponsive chromatographic matrices

Yoshikatsu Akiyama
Abstract New thermoresponsive polymers based on poly(N -(N, -alkylcarbamido)propyl methacrylamide) analogues were designed with increased hydrophobic content to facilitate temperature-dependent chromatographic separations of peptides and proteins from aqueous mobile phases. These polymer solution exhibited a lower critical solution temperature (LCST) when the alkyl group is methyl, ethyl, isopropyl, propyl, butyl, and isobutyl. However, larger alkyl groups such as hexyl and phenyl were not soluble in aqueous solutions at any temperature. Phase transition temperatures were lower for larger alkyl groups and increased with decreasing polymer molecular weight and concentration in solution. LCST dependence on polymer molecular weight and concentration is more significant compared with well-studied poly(N -isopropylacrylamide) (PIPAAm). Partition coefficient (log P) values for N -(N, -butylcarbamide)propylmethacrylamide and N -(N, -isobutylcarbamide)propyl methacrylamide (iBuCPMA) monomers are larger than that for IPAAm monomer, suggesting higher hydrophobicity than IPAAm. Chromatographic evaluation of poly(N -(N, -isobutylcarbamide)propyl methacrylamide) (PiBuCPMA) grafted silica particles in aqueous separations revealed larger k, values for peptides, insulin, insulin chain B, and angiotensin I than PIPAAm-grafted silica beads. In particular, k, values for insulin obtained from PiBuCPMA-grafted silica separations were much larger than those from PIPAAm-grafted surface separations, indicating that PiBuCPMA should be more hydrophobic than PIPAAm. These results support the introduction of alkylcarbamido groups to efficiently increase thermoresponsive polymer hydrophobicity of poly(N -alkylacrylamides) and poly(N -alkylmethacrylamides). Consequently, poly(N -(N, -alkylcarbamido)propyl methacrylamide) analogues such as PiBuCPMA and poly(N -(N, -alkylcarbamido)alkylmehacrylamide) are new thermoresponsive polymers with appropriate hydrophobic partitioning properties for protein and peptide separations in aqueous media, depending on selection of their alkyl groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5471,5482, 2008 [source]

Cyclopolymerization of perfluoroisopropenyl vinylacetate

Hirotada Fujiwara
Abstract To develop the polymerization exploiting the interconversion of fluorinated carbon radical to hydrocarbon radical, the radical cyclopolymerization of perfluoroisopropenyl vinylacetate [CF2C(CF3)OCOCH2CHCH2] (FIA) was investigated to afford a polymer possessing mainly five-membered ring structure with bimodal molecular weight distribution having 1 × 105 as the higher molecular weight. This may be the first example wherein the cyclopolymerization between usual allyl group and fluorinated vinyl group is performed. The degree of cyclization was between 70 and 80% determined by 19F NMR of as-polymerized products. The polymer preparation from perfluoroisopropenyl group, which shows scarce homopolymerization reactivity was accomplished. The mechanism that the addition of hydrocarbon radical to perfluoroisopropenyl group to produce fluorinated carbon radical followed by the intramolecular addition reaction onto allyl group to form five-membered ring is proposed. The hydrolysis of the FIA polymer afforded a polymer possessing hydrophobic fluoroalkyl group with hydrophilic hydroxyl and carboxylic acid groups. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3220,3232, 2006 [source]

Photochemical attachment of polymers on planar surfaces with a covalently anchored monolayer of a novel naphthyl ketone photochemical radical generator

K. Dayananda
Abstract A monolayer of covalently anchored, novel, binaphthyl ketone is used as a surface-confined photochemical radical generator (PRG) for anchoring a variety of polymers to silicon surfaces. The precursor PRG is synthesized by the application of a facile and novel method for the oxidation of sterically hindered benzylic hydrocarbons to carbonyl compounds. Oxidation was carried out with a stoichiometric amount of potassium peroxydisulfate, in the presence of a catalytic amount of copper sulfate in an acetonitrile/water mixture. The PRG synthesized is characterized by 1H NMR, UV, and Fourier transform infrared (FTIR). The covalently attached monolayers are characterized by X-ray photoelectron spectroscopy, ellipsometry, and water contact angle measurements. The method developed is applicable to the preparation of a monolayer of a variety of polymers on a wide range of substrates carrying surface hydroxyl groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5413,5423, 2004 [source]

Novel, biodegradable, functional poly(ester-carbonate)s by copolymerization of trans -4-hydroxy- L -proline with cyclic carbonate bearing a pendent carboxylic group

Ren-Shen Lee
Abstract Water-soluble poly(ester-carbonate) having pendent amino and carboxylic groups on the main-chain carbon is reported for the first time. This article describes the melt ring-opening/condensation reaction of trans -4-hydroxy- N -benzyloxycarbonyl- L -proline (N -CBz-Hpr) with 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) at a wide range of molar fractions. The influence of reaction conditions such as catalyst concentration, polymerization time, and temperature on the number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) of the copolymers was investigated. The polymerizations were carried out in bulk at 110 °C with 3 wt % stannous octoate as a catalyst for 16 h. The poly(ester-carbonate)s obtained were characterized by Fourier transform infrared spectroscopy, 1H NMR, differential scanning calorimetry, and gel permeation chromatography. The copolymers synthesized exhibited moderate molecular weights (Mn = 6000,14,700 g mol,1) with reasonable molecular weight distributions (Mw/Mn = 1.11,2.23). The values of the glass-transition temperature (Tg) of the copolymers depended on the molar fractions of cyclic carbonate. When the MBC content decreased from 76 to 12 mol %, the Tg increased from 16 to 48 °C. The relationship between the poly(N -CBz-Hpr- co -MBC) Tg and the compositions was in approximation with the Fox equation. In vitro degradation of these poly(N -CBz-Hpr- co -MBC)s was evaluated from weight-loss measurements and the change of Mn and Mw/Mn. Debenzylation of 3 by catalytic hydrogenation led to the corresponding linear poly(ester-carbonate), 4, with pendent amino and carboxylic groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2303,2312, 2004 [source]

Hyperbranched polyethers by ring-opening polymerization: Contribution of activated monomer mechanism

Przemys, aw Kubisa
Abstract Propagation in the cationic ring-opening polymerization of cyclic ethers involves nucleophilic attack of oxygen atoms from the monomer molecules on the cationic growing species (oxonium ions). Such a mechanism is known as the active chain-end mechanism. If hydroxyl groups containing compounds are present in the system, oxygen atoms of HO groups may compete with cyclic ether oxygen atoms of monomer molecules in reaction with oxonium ions. At the proper conditions, this reaction may dominate, and propagation may proceed by the activated monomer mechanism, that is, by subsequent addition of protonated monomer molecules to HO terminated macromolecules. Both mechanisms may contribute to the propagation in the cationic polymerization of monomers containing both functions (i.e., cyclic ether group and hydroxyl groups) within the same molecule. In this article, the mechanism of polymerization of three- and four-membered cyclic ethers containing hydroxymethyl substituents is discussed in terms of competition between two possible mechanisms of propagation that governs the structure of the products,branched polyethers containing multiple terminal hydroxymethyl groups. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 457,468, 2003 [source]

Raman spectroscopy in comparative investigations of mechanisms of binding of three molecular probes , fluorescein, eosin, and erythrosin , to human serum albumin

I.M. Vlasova
Abstract The comparative analysis of binding of three molecular fluorescent probes (fluorescein, eosin, and erythrosin), belonging to one homologous family, to human serum albumin (HSA) is made by Raman spectroscopy method. The binding of all three probes to binding Center I of HSA is registered. The character of binding of initial probe of the given homologous family , fluorescein , to protein differs from character of binding of its halogen-derivatives (eosin and erythrosin) to protein. The differences in binding of these three probes to HSA are determined by value of electronegativity of atoms of lateral radicals in structural formulas of probes and, therefore, by value of pK of their ionized groups. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

The prophylactic use of tranexamic acid and aprotinin in orthotopic liver transplantation: A comparative study ,

Antonia Dalmau
The efficacy of tranexamic acid (TA) and aprotinin (AP) in reducing blood product requirements in orthotopic liver transplantation (OLT) was compared in a prospective, randomized and double-blind study. One hundred and twenty seven consecutive patients undergoing OLT were enrolled; TA was administered to 64 OLT patients at a dose of 10mg /kg/h and aprotinin was administered to 63 OLT patients at a loading dose of 2x106 KIU followed by an infusion of 500,000 KIU/h. The portocaval shunt could not be performed in 14 OLT patients in the TA group and in 13 OLT patients in the AP group. However, all OLT patients that received either drug were included in the analysis. Perioperative management was standardized. Hemogram, coagulation tests, and blood product requirements were recorded during OLT and during the first 24 hours. No differences in diagnosis, Child score, preoperative coagulation tests, and intraoperative data were found between groups. No significant differences were observed in hemogram and intraoperative coagulation tests with the exception of activated partial thromboplastin time (aPTT). Similarly, there were no intergroup differences in transfusion requirements. Thromboembolic events, reoperations and mortality were similar in both groups. In conclusion, administration of regular doses of TA and AP during OLT did not result in large differences between the two groups. (Liver Transpl 2004;10:279,284.) [source]

Vector valued Fourier analysis on unimodular groups

Hun Hee Lee
Abstract The notion of Fourier type and cotype of linear maps between operator spaces with respect to certain unimodular (possibly nonabelian and noncompact) group is defined here. We develop analogous theory compared to Fourier types with respect to locally compact abelian groups of operators between Banach spaces. We consider the Heisenberg group as an example of nonabelian and noncompact groups and prove that Fourier type and cotype with respect to the Heisenberg group implies Fourier type with respect to classical abelian groups. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]