bluuebunny/crossref_metadata_2025 huggingface dataset:
The causes and spatial pattern of land degradation risk in southern Mauritania using multitemporal AVHRR‐NDVI imagery and field data
Authors: Thiam A. K.
Published: January 2003

Multitemporal 1 km NOAA/AVHRR Normalized Difference Vegetation Index (NDVI) maximum composite imagery was utilized in combination with rainfall, soil types, and field survey data on dominant rural activities to assess the risk of land degradation in southern Mauritania. Mauritania is one of eight continental West African Sahel countries that stretch from Chad to the northwestern Atlantic coast, and from the southern fringe of the Sahara Desert to the northern limit of the Sudanian climatic zone. The major environmental problem these countries are currently facing is the temporally and spatially erratic character of rainfall, frequently leading to general or local droughts since the late‐1960s with subsequent increase of human pressure on the natural resource base and degradation. Image deviation was applied to maximum NDVI composites of the growing season (June to October) for the period 1990–99 to detect temporal and spatial change patterns over the study area. Only pixels whose values were lower than their temporal mean minus 0ċ5 standard deviation were retained as areas under threat. These were combined with soil types and the spatial pattern of deforestation (fuelwood and building material collection areas) grazing, and agricultural land to determine the causes of lowering primary biological productivity. The results show that the below‐normal NDVI values generally coincide with the patterns of below‐normal rainfall: deforestation, and overgrazing areas, agricultural land, and low primary biological productivity soil types. Thus the observed substantial decrease in biomass production results from the combined impacts of frequent rainfall deficits and uncontrolled resource‐base exploitation by the local population. Large chunks of land that show consistent low biomass production are also observed on unproductive soils. Finally, the below‐normal rainfall, below‐average NDVI values, and human impacts images were cross‐classified to produce a three‐class (low, moderate, and high) land degradation risk map along with a table containing the area covered by each class. A Boolean mask of the degradation risk map applied to the soils map showed that all soil types in southern Mauritania are at risk of degradation. These products could serve as a strong basis for decision making in regard to planning resource allocation for environmental rehabilitation. Copyright © 2002 John Wiley & Sons, Ltd.
Local innovation in a global context: documenting farmer initiatives in land husbandry through WOCAT
Authors: Critchley W. R. S. , Mutunga K.
Published: January 2003

Innovation by farmers in land husbandry was the focus of the project Promoting Farmer Innovation (PFI), which was operational in Kenya, Tanzania and Uganda from 1997 to 2001. One of the project's final activities was to document best‐bet innovations. It was decided to make use of a questionnaire available under the World Overview of Conservation Approaches and Technologies (WOCAT) to collect data on a selection of these technologies. Data were fed back into WOCAT's global database. Eighteen technical initiatives were recorded in this way, and the findings added to existing data and in‐house knowledge. This information was analysed and a technical report produced (Mutunga and Critchley, 2001). The technologies included turning gullies into gardens, digging planting pits for millet and sorghum and harvesting water from roads. Each combined aspects of land conservation with improved plant production. While several required relatively high initial labour input, all were considered economically beneficial by the farmers. Adoption by other farmers was generally rapid, partially as a result of farmer to farmer visits under PFI. The value of the PFI‐WOCAT exercise was not restricted to recording and disseminating information, however. It was also a test of the utility of WOCAT within a project. There were a number of interesting findings. Although those who filled the questionnaires found it an onerous task, they felt that they learned a good deal as they went through the process. One of the main conclusions was that the questionnaire could be a very valuable template to help guide internal monitoring and evaluation, if used from the start of a project intervention. Copyright © 2002 John Wiley & Sons, Ltd.
Exploring environmental causes of altered ras effects: Fragmentation plus integration?
Authors: Porta Miquel , Ayude Daniel , Alguacil Juan , Jariod Manuel
Published: January 2003

Mutations in ras genes are the most common abnormality of oncogenes in human cancer and a major example of activation by point mutation. Experimental and epidemiological studies support the notion that Ki‐ras activation and expression may be chemically related. We discuss the potential role of several environmental compounds in the induction or promotion of ras mutations in humans, with a focus on exocrine pancreatic cancer, the human tumor with the highest prevalence at diagnosis of Ki‐ras mutations. Organochlorine compounds, organic solvents, and coffee compounds may play an indirect role in causing Ki‐ras mutations, rather than as direct inducers of the mutations. Although for some organochlorine compounds the induction of point mutations in ras oncogenes cannot be excluded, it seems more likely that the effects of these compounds are mediated through nongenomic or indirectly genotoxic mechanisms of action. Organic solvents also may act via enzymatic induction of ras mutagens or by providing a proliferation advantage to ras‐mutated cell clones. In exocrine pancreatic cancer, caffeine, other coffee compounds, or other factors with which coffee drinking is associated could modulate Ki‐ras activation by interfering with DNA repair, cell‐cycle checkpoints, and apoptosis. Asbestos, cigarette smoking, and some dietary factors also may be involved in the initiation or the promotion of Ki‐ras mutations in lung and colon cancers. Further development of the mechanistic scenarios proposed here could contribute to a meaningful integration of biological, clinical, and environmental knowledge on the causes of altered ras effects. © 2003 Wiley‐Liss, Inc.
Exceptional activity of murine glutathione transferase A1‐1 against (7R,8S)‐dihydroxy‐(9S,10R)‐epoxy‐7,8,9,10‐tetrahydrobenzo[a]pyrene–induced DNA damage in stably transfected cells
Authors: Guo Jianxia , Pan Su‐Shu , Singh Shivendra V.
Published: January 2003

We have shown previously that the alpha class murine glutathione transferase (GST) isoenzyme mGSTA1‐1, unlike other mammalian class alpha GSTs, is highly efficient in catalyzing the glutathione (GSH) conjugation of (7R,8S)‐dihydroxy‐(9S,10R)‐epoxy‐7,8,9,10‐tetrahydrobenzo[a]pyrene [(+)‐anti‐BPDE], which is the ultimate carcinogenic metabolite of benzo[a]pyrene. The present studies were undertaken to determine the efficacy of mGSTA1‐1 in cellular protection against (+)‐anti‐BPDE‐induced DNA damage in HepG2 cells stably transfected with mGSTA1 cDNA. Untransfected HepG2 cells, vector‐transfected HepG2 cells (HepG2‐vector), and cells transfected with mGSTA4 cDNA (HepG2‐mGSTA4), an alpha class murine GST isoenzyme with low (+)‐anti‐BPDE‐GSH conjugating activity, were used as controls for comparison. Intracellular GSH conjugation of (+)‐anti‐BPDE was significantly higher in mGSTA1‐1–overexpressing HepG2 cells (HepG2‐mGSTA1) than in HepG2‐vector or HepG2‐mGSTA4 cells. The formation of DNA‐adducts of (+)‐anti‐BPDE, following a 10‐, 20‐, or 30‐min exposure to 0.1, 0.5, or 1.0 μM [3H](+)‐anti‐BPDE, was reduced significantly in cells transfected with mGSTA1‐1 compared with HepG2‐vector or untransfected HepG2 cells. Consistent with the results with purified protein, overexpression of mGSTA4‐4 had no effect on (+)‐anti‐BPDE–induced DNA damage. The results of the present study indicated that mGSTA1‐1 was exceptionally effective in affording protection against (+)‐anti‐BPDE–induced DNA damage in a cellular system. © 2003 Wiley‐Liss, Inc.
New scope for synthesis of divinyl ether and maleic anhydride copolymer with narrow molecular mass distribution
Authors: Volkova I. F. , Gorshkova M. Yu. , Ivanov P. E. , Stotskaya L. L.
Published: January 2003

The alternating copolymer of divinyl ether and maleic anhydride (DIVEMA) possesses diverse biological activity and uses for production of drug delivery systems. DIVEMA's biological effects are determined by molecular mass, therefore it is necessary to have information about copolymer molecular mass and its distribution. A direct method for gel permeation chromatography analysis of DIVEMA molecular mass characteristics in aqua solution without any preliminary modification was developed. The effect of a number of factors (the concentration of monomers and their ratios, the concentration of initiator, the nature of the solvents) on DIVEMA's solution properties and molecular mass distribution was studied by gel permeation chromatography and viscometry. The approach to synthesis of DIVEMA with narrow molecular mass distribution was designed. The substantial influence of water on DIVEMA molecular mass characteristics was determined. The proposal was made that water may play a part in the formation of charge‐transfer complexes playing a significant role in copolymerization. Copyright © 2003 John Wiley & Sons, Ltd.
“Length and breadth” polyrotaxane structures—a new concept in three‐dimensional polymeric systems
Authors: Azzam T. , Peppas N. A. , Slomkowski S. , Domb A. J.
Published: January 2003

This work describes the synthesis and characterization of rotaxane‐crosslinked polymers using macrocyclic poly(ethylene glycol) (PEG) attached to a vinyl moiety. Diacyl chlorides (fumaryl or itaconyl) and PEG400 were condensed under high dilution conditions to yield the corresponding macrocyclic monomers. These were purified by column chromatography and identified by mass spectroscopy utilizing MALDI‐TOF technique and 1H‐NMR. Radical polymerization in bulk of these macrocyclic monomers using benzoyl peroxide as initiator, resulted in soft polymers which are soluble in various organic solvents. Under the same conditions, insoluble gels were obtained by copolymerization of the ring‐substituted vinyl monomers with either hydrophobic vinyl monomers (methyl methacrylate, MMA) or with a hydrophilic vinyl monomer (2‐hydroxy ethyl methacrylate, HEMA). These results indicate that crosslinking was obtained due to threading of linear chains through macrocycles which act as crosslinkers. The swelling ratios of the gels indicated a correlation between the molar ratios of the macrocycle and the linear chain incorporated with it. Copyright © 2003 John Wiley & Sons, Ltd.
Syntheses of biodegradable (multi) block copolymers, star‐shaped polyesters and networks via ring‐expansion polymerization
Authors: Kricheldorf Hans R.
Published: January 2003

Numerous cyclic dibutyltin alkoxides were prepared by condensation of Bu2Sn(OMe)2 with various short or long α,ω‐diols. Insertion of lactones or lactide into the SnO bonds resulted in ring‐expansion polymerizations which allowed a control of the ring size (chain length) via the monomer initiator ratio. When the cyclic initiators were derived from a long α,ω‐diol, such as poly(tetrahydrofuran)diols or polysiloxane diols, the resulting cyclic polylactones were necessarily cyclic triblock copolymers. The high nucleophilicity of the Sn‐O bond enabled ring‐opening polycondensations with dicarboxylic acid dichlorides yielding multiblock copolyesters. Condensations with monocarboxylic acids yielded functionalized A‐B‐A triblock copolymers. Polycondensation with trifunctional acid chlorides yielded biodegradable networks. Hydroxyethylated pentaerythritol condensed with Bu2Sn(OMe)2 yielded a spirocyclic initiator. Ring‐expansion polymerization with lactones followed by acylation with carboxylic acid chlorides produces star‐shaped polylactones having functional endgroups. Biodegradable networks were also obtained when bisstannylenated α‐glucose methyl glycoside was used as initiator for ϵ‐caprolactone, and when the resulting spirocyclic polylactone was polycondensed with sebacoyl chloride. Copyright © 2003 John Wiley & Sons, Ltd.
The system polyamide/sulfamate/dipentaerythritol: flame retardancy and chemical reactions
Authors: Lewin Menachem , Brozek Jiri , Martens Marvin M.
Published: January 2003

The use of sulfur compounds and particularly sulfamates for flame‐retarding cellulose and other polymers is reviewed. Recent results on flame‐retarding polyamides in this laboratory are presented. The system developed requires the use of 1.5–2.5 wt% of ammonium sulfamate (AS) or diammonium imidobisulfonate (DIBS) together with 0.4–0.85 wt% of pentaerythritol (petol) or dipentaerythritol (dipenta) to obtain fully flame‐retardant polyamide 6 and 66. The properties of the flame‐retarded products, obtained both by Brabender mixing and by twin‐screw extrusion are: UL‐94 rating of V‐0 on bars of 1/16″ and 1/32″; no flaming drips; very low burn time; tensile strength of 11 KPSI; 10–20% elongation and CTI values of ca. 600 V. Thermoanalytical and FTIR data are presented that indicate the thermal stability of the system and the chemical reactions occurring. Mechanisms are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Molecular mass distribution of polycations and dextrans by high‐performance size exclusion chromatography
Authors: Kumar Neeraj , Azzam Tony , Domb Abraham J.
Published: January 2003

A high‐performance size exclusion chromatographic (HPSEC) method for molecular mass distribution (MMD) was developed for polycations. Results obtained from HPSEC using UV and RI detectors were compared with the viscosity measurements. Pullulan standards were used for Mw calibration. It is concluded that HPSEC with a UV detector offers a sensitive and simple method that has the required accuracy. Degradation studies following this method indicate that dextrans are stable at a temperature of 55 °C and at different pH solutions for up to 7 days. Copyright © 2003 John Wiley & Sons, Ltd.
Direction‐sensitive stress measurements with carbon nanotube sensors
Authors: Zhao Qing , Frogley Mark D. , Wagner H. Daniel
Published: January 2003

Single‐wall nanotubes (SWNTs) embedded in polymer can be used as mechanical sensors because the position of the D* Raman band of SWNTs is strongly dependent on the strain transferred from the matrix to the nanotubes. In order to detect the stress (or strain) information in specific directions, polarized Raman spectroscopy is used to select out the signal from the nanotubes that are parallel to the polarization direction. This method is demonstrated by measuring the stress distribution around a circular hole in the SWNT/polymer composites under uniaxial tension. Then the stress field in a polymer matrix in the vicinity of a single glass fiber is mapped on the micrometer scale. A stress concentration zone is observed around the fiber end. The importance of this technique and the measurements for composite design and micro‐mechanical models is discussed briefly. Copyright © 2003 John Wiley & Sons, Ltd.
Ion‐doping role in photoinduced processes in pyridine‐containing polymeric viscous solutions
Authors: Vaganova Evgenia , Meshulam Gilia , Kotler Zvi , Yitzchaik Shlomo
Published: January 2003

The photochemical reaction in poly(4‐vinyl pyridine)/pyridine compositions under irradiation at 254 nm results in new electronic and structural properties. Photoinduced electronic and structural properties can be assigned to the appearance of the pyridine ring‐opening photoproducts and interaction of the latter between themselves and with pyridine moieties. Doping of the composition with hydrochloric acid or lithium chloride can control the photochemical reaction, especially the interaction of the ring‐opening photoproducts. The cleaved form of the compounds and the aggregates of the latter act as the crosslinkers in the system. Optical property changes are followed by structural changes. Depending on the doped compound, different long‐wave‐shifted emissions arise in the compositions after irradiation. The far long‐wave‐shifted emission appears in the system doped with lithium chloride, ­which is unstable and disappears shortly after cessation of irradiation, while the red‐emitting centers of the undoped system are stable and exhibit a second harmonic generation (SHG) signal. Copyright © 2003 John Wiley & Sons, Ltd.
Polymeric biomaterials synthesized by radiation techniques – current studies at IARC, Poland
Authors: Ulanski Piotr , Janik Ireneusz , Kadlubowski Slawomir , Kozicki Marek , Kujawa Piotr , Pietrzak Miroslaw , Stasica Przemyslaw , Rosiak Janusz M.
Published: January 2003

For over 15 years the Institute of Applied Radiation Chemistry in Lodz, Poland, has been involved in studies on new polymeric biomaterials. Some of the technologies developed employ radiation techniques for the synthesis of crosslinked products (mainly hydrogels), for surface modification and for sterilization. An example of a mature technology of this kind is hydrogel wound dressings, now being produced on a large scale and available on the market in many Central European countries. Another advanced project is a hydrogel system for healing endometrium cancer by precise, local drug delivery. Preliminary clinical tests with over 70 patients have been completed with very good results.

Current research projects, besides further development of the above mentioned systems, include: a hydrogel‐based system for local, controlled drug delivery; polymer materials for encapsulation of living cells and for the construction of hybrid artificial organs; a new approach to the synthesis of polymeric material for intervertebral disc implant; temperature‐sensitive membranes and supports for cell cultures; hydrogel phantoms for low‐dose, three‐dimensional radiation dosimetry; degradation‐resistant nanogels and microgels for biomedical purposes (e.g. synovial fluid substitute); hydrogel‐based dietary products and adjustment of the molecular weight of biopolymers by ultrasound and ionizing radiation. Copyright © 2003 John Wiley & Sons, Ltd.
Conductive polymer composites (CPCs): comparison of electrical properties of poly(ethylene‐co‐ethyl acrylate)‐carbon black with poly(butylene terephthalate)/poly(ethylene‐co‐ethyl acrylate)‐carbon black
Authors: Feller J. F. , Linossier I. , Levesque G.
Published: January 2003

We have studied the influence of the addition of poly(butylene terephthalate) (PBT) to poly(ethylene‐co‐ethyl acrylate)‐carbon black (EEA‐CB) on the electrical properties of the blends, namely the resistivity and power dissipation of the monophasic and diphasic systems. The morphology of the latter blend is characterized by two interpenetrated immiscible phases which provide a good thermal stability to the composite up to at least 170 °C. Power can be regularly delivered without a negative temperature coefficient (NTC) effect at 100 °C where poly(ethylene‐co‐ethyl acrylate) melts. However, the significant decrease of positive temperature coefficient (PTC) amplitude compared to the monophasic systems reduces the self‐regulating heating ability. The PTC effect amplitude decrease was studied by some of its known origins (thermal expansion, melting of crystalline phase, carbon black localization). Correlation of the composites resistivity with linear expansion, the melting process of EEA, and the volume expansion of PBT, show that none of these parameters can alone explain the electrical properties' evolution with temperature. Our interpretation of the PTC effect amplitude decrease is based on the PBT matrix lower thermal expansion and on the increased carbon black content located at the interface. Copyright © 2003 John Wiley & Sons, Ltd.
Polyanhydrides with hydrophobic terminals
Authors: Krasko Michal Y. , Shikanov Ariella , Kumar Neeraj , Domb Abraham J.
Published: January 2003

Polyanhydrides prepared from hydrophobic diacids such as sebacic acid (SA) are brittle and unstable in storage and degrade with time. The physical properties of these polyanhydrides have been improved by introducing hydrophobic terminals into the main chain which has provided better stability and controlled the molecular weight. The effects of molecular weight, pliability, biodegradation and drug release on polymer were investigated. Poly(sebacic anhydride) (PSA) was terminated with the unsaturated fatty acids, ricinoleic acid, oleic acid, linoleic acid and the cholesterol derivative, lithocholic acid, and prepared in the weight ratio of 70:30. Polymers thus obtained had a predictable molecular weight of 3–8 × 103 and an Mp of 60–76 °C and degraded at the rate of 3.3–7.6 mg/cm2/day. The rate of degradation was dependent on the contents of the hydrophobic terminals. These polyanhydrides were found to be useful for the release of hydrophobic and hydrophilic drugs for 2–3 weeks in vitro. Copyright © 2003 John Wiley & Sons, Ltd.
Molecular engineering of dye‐doped polymers for optoelectronics
Authors: Ishchenko Alexander
Published: January 2003

The main approaches to molecular engineering of prospective dye‐doped polymer matrices for optoelectronics have been considered. The advantages of such matrices over polymers and dyes separately were analyzed. It was shown that these advantages can be realized in the case where a doping of polymers by low‐molecular‐weight dyed impurities does not essentially distort spectral, luminescent and nonlinear optical properties of the individual components of polymer composition. The influence of polymer nature and chemical constitution of organic dyes on photophysical and photochemical properties of these matrices was analyzed. Processes of dye aggregation in polymers were characterized. Their influence on photophysical properties and the photochemical stability of dye‐doped materials was discussed. The different approaches for struggle with it is offered. The influence of the method of introduction of a dye into a polymer on the output parameters of dyed materials was considered. The main paths of energy degradation of electronic excitation in such materials – internal conversion, electron transfer and photoisomerization – were analyzed. The role of dyes in the process of generation, in recombination and in the carriage of charges in photoconductive polymers was discussed. The prospects for the application of dye‐doped polymer materials as passive Q‐switches of solid‐state lasers, as active laser media with large Stokes shift, as luminescent solar converters and as electroluminescent emitters were demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
PLA‐PEG nanospheres: new carriers for transmucosal delivery of proteins and plasmid DNA
Authors: Vila Ana , Sánchez Alejandro , Pérez Celso , Alonso María J.
Published: January 2003

There is little doubt that advances in polymer synthesis and in the design of delivery systems will have a profound impact on future therapeutics and immunization practices based on complex molecules such as proteins and plasmids. Our approach in this area has been the design of nanoparticles made of poly(lactic acid)‐poly(ethyleneglycol) (PLA‐PEG), for mucosal delivery of proteins and plasmid DNA. The technologies for the formation of these nanoparticles, were conveniently adapted in order to encapsulate proteins efficiently (i.e., tetanus toxoid) and DNA (i.e., pCMV‐βGal) into a PLA core coated by PEG. These techniques include the w/o/w emulsion–solvent evaporation technique and the w/o emulsion–solvent diffusion technique, both providing high protein/DNA loadings. Results showed that the presence of a PEG coating around the nanoparticles significantly enhanced their stability in the gastrointestinal fluids, as well as in contact with mucus enzymes. This coating was also found to be responsible for the enhanced transport of 125I‐radiolabelled tetanus toxoid and its delivery to the blood circulation and the lymph nodes, following nasal administration to rats. Additionally, fluorescent microscopy studies aimed at examining the interaction and transport of the nanoparticles through the nasal mucosa demonstrated that these nanoparticles can, indeed, cross the nasal epithelium. Finally, the efficacy of these PEG‐coated nanoparticles as nasal vaccine delivery vehicles was shown in vivo. More specifically, the tetanus toxoid‐loaded nanoparticles were able to elicit enhanced and long‐lasting immunogenic responses following nasal administration. On the other hand, a single dose of encapsulated DNA administered intranasally led to a significant systemic antibody response to the encoded protein, confirming that plasmid DNA can be encapsulated in PLA‐PEG nanoparticles with significant retention of biological function. To summarize, the data reported in the present paper provide evidence of the potential of PLA‐PEG nanoparticles as carriers for the transport of proteins and DNA across mucosal surfaces. Copyright © 2003 John Wiley & Sons, Ltd.
Convergent and discriminant construct validity of the internalizing symptoms scale for children with the BASC‐SRP‐C
Authors: MERRELL KENNETH W. , BLADE RICHARD L. , LUND JACQUELINE , KEMPF KARI K.G.
Published: January 2003

This brief report details a study of the construct validity of the Internalizing Symptoms Scale for Children (ISSC) in comparison with the Child Self‐Report Form of the Behavioral Assessment System for Children (BASC). Using self‐reports of 121 students ages 8–12 from general education classes, who were administered both measures, correlational data were obtained between the scores of the two instruments. ISSC factor and total scores were found to have weak associations with the BASC School Adjustment Scales, and negatively associations with the BASC personal adjustment scales, providing discriminant evidence of the construct validity of the ISSC. Moderate to strong correlations were found between ISSC scores and the BASC Clinical Maladjustment, Other Problems, and Emotional Symptoms Index scores, evidencing convergent construct validity between the two measures. These results support the validity and clinical use of the ISSC as a measure of internalizing symptoms and emotional problems. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 139–144, 2003.
Social desirability and behavior rating scales: An exploratory study with the Child Behavior Checklist/4–18
Authors: MERYDITH SCOTT P. , PROUT H. THOMPSON , BLAHA JOHN
Published: January 2003

This study investigated the relationship between the Child Behavior Checklist/4–18 (CBCL/4–18) and two modified measures of social desirability, the Marlowe‐Crowne Social Desirability Scale and the Edwards Social Desirability Scale with a sample of 65 parents of normal children from grades K–7. Results from correlational and multiple regression analyses showed that the Aggressive Behaviors and Attention Problems cross‐informant syndromes were modestly associated with social desirability scale scores. The relevance of findings are discussed in terms of the susceptibility of behavior rating scales to the self‐deception and other‐deception factors of social desirability [Paulhus, D.L. (1984). In: J.P. Robinson et al., (eds.) Measures of social psychological attitudes. (pp. 17–59). San Diego: Academic Press.] and fake‐good response sets. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 225–235, 2003.
Conduct disorder in girls: Diagnostic and intervention issues
Authors: DELLIGATTI NINA , AKIN‐LITTLE ANGELEQUE , LITTLE STEVEN G.
Published: January 2003

Current prevalence rates of Conduct Disorder (CD) in girls may be an underestimate due to inappropriate diagnostic criteria, biased perceptions by those responsible for reporting problematic behavior, and differential social constraints for each gender. Relatively few published studies of CD and related behaviors in girls exist. Available evidence suggests adolescent girls with CD have a poor outcome including early and violent death, arrest, substance abuse and dependence, antisocial personality disorder, failure to finish high school, pregnancy, sexual promiscuity, and contraction of sexually transmitted disease. Even with its relatively low, possibly underestimated prevalence rate in comparison with that of boys, CD has been found to be the second most common psychiatric disorder in adolescent girls. In addition to examining possible reasons for the lack of research on CD in girls, this article reviews possible risk factors and suggested assessment and intervention strategies for this population. Particular attention is paid to implications for practitioners in the school setting. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 183–192, 2003.
Job satisfaction, burnout, and perceived effectiveness of “in‐house” versus traditional school psychologists
Authors: PROCTOR BRILEY E. , STEADMAN TARA
Published: January 2003

The present study examined whether school psychologists who serve a single school (“In‐House” group) differed from school psychologists who serve several schools concurrently (“Traditional” group) in the three areas of job satisfaction, burnout, and effectiveness as perceived by the school psychologist. A total of 63 school psychology practitioners were surveyed using a 28‐item questionnaire developed specifically for this study that yielded scores for Job Satisfaction, Burnout, and Perceived Effectiveness. Results of a multivariate analysis of variance (MANOVA) indicated that the In‐House group reported higher rates of satisfaction and perceived effectiveness and lower rates of burnout than did the traditional group. Items that distinguished between the two groups related to job diversity, caseload, others' familiarity with the school psychologist, the school psychologists' level of integration into school activities, and administrators' knowledge about the school psychologists' capabilities. Suggestions for further research and implications for current practice are discussed. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 237–243, 2003.
Relations between measures of Cattell‐Horn‐Carroll (CHC) cognitive abilities and mathematics achievement across the school‐age years
Authors: FLOYD RANDY G. , EVANS JEFFREY J. , McGREW KEVIN S.
Published: January 2003

Cognitive clusters from the Woodcock‐Johnson III (WJ III) Tests of Cognitive Abilities that measure select Cattell‐Horn‐Carroll broad and narrow cognitive abilities were shown to be significantly related to mathematics achievement in a large, nationally representative sample of children and adolescents. Multiple regression analyses were used to predict performance on the Math Calculation Skills and Math Reasoning clusters from the WJ III Tests of Achievement for 14 age groups ranging in age from 6 to 19 years. Comprehension‐Knowledge (Gc) demonstrated moderate relations with Math Calculation Skills after the early school‐age years and moderate to strong relations with Math Reasoning. Fluid Reasoning (Gf), Short‐term Memory (Gsm), and Working Memory generally demonstrated moderate relations with the mathematics clusters. Processing Speed (Gs) demonstrated moderate relations with Math Reasoning during the elementary school years and moderate to strong relations with Math Calculation Skills. During the earliest ages of the analysis, Long‐term Retrieval (Glr) demonstrated moderate relations with the mathematics clusters, and Auditory Processing (Ga) demonstrated moderate relations with Math Calculation Skills. Visual‐Spatial Thinking (Gv) generally demonstrated nonsignificant relations with the mathematics clusters. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 155–171, 2003.
Strategies for structural proteomics of prokaryotes: Quantifying the advantages of studying orthologous proteins and of using both NMR and X‐ray crystallography approaches
Authors: Savchenko Alexei , Yee Adelinda , Khachatryan Anna , Skarina Tatiana , Evdokimova Elena , Pavlova Marina , Semesi Anthony , Northey Julian , Beasley Steven , Lan Ning , Das Rajdeep , Gerstein Mark , Arrowmith Cheryl H. , Edwards Aled M.
Published: January 2003

Only about half of non‐membrane‐bound proteins encoded by either bacterial or archaeal genomes are soluble when expressed in Escherichia coli (Yee et al., Proc Natl Acad Sci USA 2002;99:1825–1830;
Christendat et al., Prog Biophys Mol Biol 200;73:339–345). This property limits genome‐scale functional and structural proteomics studies, which depend on having a recombinant, soluble version of each protein. An emerging strategy to increase the probability of deriving a soluble derivative of a protein is to study different sequence homologues of the same protein, including representatives from thermophilic organisms, based on the assumption that the stability of these proteins will facilitate structural analysis. To estimate the relative merits of this strategy, we compared the recombinant expression, solubility, and suitability for structural analysis by NMR and/or X‐ray crystallography for 68 pairs of homologous proteins from E. coli and Thermotoga maritima. A sample suitable for structural studies was obtained for 62 of the 68 pairs of homologs under standardized growth and purification procedures. Fourteen (eight E. coli and six T. maritima proteins) samples generated NMR spectra of a quality suitable for structure determination and 30 (14 E. coli and 16 T. maritima proteins) samples formed crystals. Only three (one E. coli and two T. maritima proteins) samples both crystallized and had excellent NMR properties. The conclusions from this work are: (1) The inclusion of even a single ortholog of a target protein increases the number of samples for structural studies almost twofold; (2) there was no clear advantage to the use of thermophilic proteins to generate samples for structural studies; and (3) for the small proteins analyzed here, the use of both NMR and crystallography approaches almost doubled the number of samples for structural studies. Proteins 2003;50:392–399. © 2003 Wiley‐Liss, Inc.
Structure of the Clade 1 catalase, CatF of Pseudomonas syringae, at 1.8 Å resolution
Authors: Carpena Xavi , Soriano Manuel , Klotz Martin G. , Duckworth Harry W. , Donald Lynda J. , Melik‐Adamyan William , Fita Ignacio , Loewen Peter C.
Published: January 2003

Catalase CatF of Pseudomonas syringae has been identified phylogenetically as a clade 1 catalase, closely related to plant catalases, a group from which no structure has been determined. The structure of CatF has been refined at 1.8 Å resolution by using X‐ray synchrotron data collected from a crystal flash‐cooled with liquid nitrogen. The crystallographic agreement factors R and Rfree are, respectively, 18.3% and 24.0%. The asymmetric unit of the crystal contains a whole molecule that shows accurate 222‐point group symmetry. The crystallized enzyme is a homotetramer of subunits with 484 residues, some 26 residues shorter than predicted from the DNA sequence. Mass spectrometry analysis confirmed the absence of 26 N‐terminal residues, possibly removed by a periplasmic transport system. The core structure of the CatF subunit was closely related to seven other catalases with root‐mean‐square deviations (RMSDs) of 368 core Cα atoms of 0.99–1.30 Å. The heme component of CatF is heme b in the same orientation that is found in Escherichia coli hydroperoxidase II, an orientation that is flipped 180° with respect the orientation of the heme in bovine liver catalase. NADPH is not found in the structure of CatF because key residues required for nucleotide binding are missing; 2129 water molecules were refined into the model. Water occupancy in the main or perpendicular channel of CatF varied among the four subunits from two to five in the region between the heme and the conserved Asp150. A comparison of the water occupancy in this region with the same region in other catalases reveals significant differences among the catalases. Proteins 2003;50:423–436. © 2003 Wiley‐Liss, Inc.
Structure validation by Cα geometry: ϕ,ψ and Cβ deviation
Authors: Lovell Simon C. , Davis Ian W. , Arendall W. Bryan , de Bakker Paul I. W. , Word J. Michael , Prisant Michael G. , Richardson Jane S. , Richardson David C.
Published: January 2003

Geometrical validation around the Cα is described, with a new Cβ measure and updated Ramachandran plot. Deviation of the observed Cβ atom from ideal position provides a single measure encapsulating the major structure‐validation information contained in bond angle distortions. Cβ deviation is sensitive to incompatibilities between sidechain and backbone caused by misfit conformations or inappropriate refinement restraints. A new ϕ,ψ plot using density‐dependent smoothing for 81,234 non‐Gly, non‐Pro, and non‐prePro residues with B < 30 from 500 high‐resolution proteins shows sharp boundaries at critical edges and clear delineation between large empty areas and regions that are allowed but disfavored. One such region is the γ‐turn conformation near +75°,−60°, counted as forbidden by common structure‐validation programs; however, it occurs in well‐ordered parts of good structures, it is overrepresented near functional sites, and strain is partly compensated by the γ‐turn H‐bond. Favored and allowed ϕ,ψ regions are also defined for Pro, pre‐Pro, and Gly (important because Gly ϕ,ψ angles are more permissive but less accurately determined). Details of these accurate empirical distributions are poorly predicted by previous theoretical calculations, including a region left of α‐helix, which rates as favorable in energy yet rarely occurs. A proposed factor explaining this discrepancy is that crowding of the two‐peptide NHs permits donating only a single H‐bond. New calculations by Hu et al. [Proteins 2002 (this issue)] for Ala and Gly dipeptides, using mixed quantum mechanics and molecular mechanics, fit our nonrepetitive data in excellent detail. To run our geometrical evaluations on a user‐uploaded file, see MOLPROBITY (http://kinemage.biochem.duke.edu) or RAMPAGE (http://www‐cryst.bioc.cam.ac.uk/rampage). Proteins 2003;50:437–450. © 2003 Wiley‐Liss, Inc.
Structure and dynamics of the potato carboxypeptidase inhibitor by 1H and 15N NMR
Authors: González Carlos , Neira José Luis , Ventura Salvador , Bronsoms Silvia , Rico Manuel , Avilés Francese X.
Published: January 2003

The solution structure and backbone dynamics of the recombinant potato carboxypeptidase inhibitor (PCI) have been characterized by NMR spectroscopy. The structure, determined on the basis of 497 NOE‐derived distance constraints, is much better defined than the one reported in a previous NMR study, with an average pairwise backbone root‐mean‐square deviation of 0.5 Å for the well‐defined region of the protein, residues 7–37. Many of the side‐chains show now well‐defined conformations, both in the hydrophobic core and on the surface of the protein. Overall, the solution structure of free PCI is similar to the one that it shows in the crystal of the complex with carboxypeptidase A. However, some local differences are observed in regions 15–21 and 27–29. In solution, the six N‐terminal and the two C‐terminal residues are rather flexible, as shown by 15N backbone relaxation measurements. The flexibility of the latter segment may have implications in the binding of the inhibitor by the enzyme. All the remaining residues in the protein are essentially rigid (S2 > 0.8) with the exception of two of them at the end of a short 3/10 helix. Despite the small size of the protein, a number of amide protons are protected from exchange with solvent deuterons. The slowest exchanging protons are those in a small two‐strand β‐sheet. The unfolding free energies, as calculated from the exchange rates of these protons, are around 5 kcal/mol. Other protected amide protons are located in the segment 7–12, adjacent to the β‐sheet. Although these residues are not in an extended conformation in PCI, the equivalent residues in structurally homologous proteins form a third strand of the central β‐sheet. The amide protons in the 3/10 helix are only marginally protected, indicating that they exchange by a local unfolding mechanism, which is consistent with the increase in flexibility shown by some of its residues. Backbone alignment‐based programs for folding recognition, as opposite to disulfide‐bond alignments, reveal new proteins of unrelated sequence and function with a similar structure. Proteins 2003;50:410–422. © 2003 Wiley‐Liss, Inc.
Refinement of protein structures in explicit solvent
Authors: Linge Jens P. , Williams Mark A. , Spronk Christian A.E.M. , Bonvin Alexandre M. J. J. , Nilges Michael
Published: January 2003

We present a CPU efficient protocol for refinement of protein structures in a thin layer of explicit solvent and energy parameters with completely revised dihedral angle terms. Our approach is suitable for protein structures determined by theoretical (e.g., homology modeling or threading) or experimental methods (e.g., NMR). In contrast to other recently proposed refinement protocols, we put a strong emphasis on consistency with widely accepted covalent parameters and computational efficiency. We illustrate the method for NMR structure calculations of three proteins: interleukin‐4, ubiquitin, and crambin. We show a comparison of their structure ensembles before and after refinement in water with and without a force field energy term for the dihedral angles; crambin was also refined in DMSO. Our results demonstrate the significant improvement of structure quality by a short refinement in a thin layer of solvent. Further, they show that a dihedral angle energy term in the force field is beneficial for structure calculation and refinement. We discuss the optimal weight for the energy constant for the backbone angle omega and include an extensive discussion of meaning and relevance of the calculated validation criteria, in particular root mean square Z scores for covalent parameters such as bond lengths. Proteins 2003;50:496–506. © 2003 Wiley‐Liss, Inc.
Hydration in proteins observed by high‐resolution neutron crystallography
Authors: Chatake Toshiyuki , Ostermann Andreas , Kurihara Kazuo , Parak Fritz G. , Niimura Nobuo
Published: January 2003

It is well known that water molecules surrounding a protein play important roles in maintaining its structural stability. Water molecules are known to participate in several physiological processes through the formation of hydrogen bonds. However, the hydration structures of most proteins are not known well at an atomic level at present because X‐ray protein crystallography has difficulties to localize hydrogen atoms. In contrast, neutron crystallography has no problem in determining the position of hydrogens with high accuracy.1 In this article, the hydration structures of three proteins are described— myoglobin, wild‐type rubredoxin, and a mutant rubredoxin—the structures of which were solved at 1.5‐ or 1.6‐Å resolution by neutron structure determination. These hydration patterns show fascinating features and the water molecules adopt a variety of shapes in the neutron Fourier maps, revealing details of intermolecular hydrogen bond formation and dynamics of hydration. Our results further show that there are strong relationships between these shapes and the water environments. Proteins 2003;50:516–523. © 2003 Wiley‐Liss, Inc.
Molecular dynamics simulation reveals a surface salt bridge forming a kinetic trap in unfolding of truncated Staphylococcal nuclease
Authors: Gruia Andreea D. , Fischer Stefan , Smith Jeremy C.
Published: January 2003

Surface salt bridges are ubiquitous in globular proteins. Their contribution to protein stability has been extensively debated in the past decade. Here, molecular dynamics simulations are performed starting from a non‐equilibrium state of Staphylococcal nuclease (SNase) with C‐terminal truncation (SNaseΔ). The results indicate a key role in the unfolding of the surface salt bridge between arginine 105 and glutamate 135. Experimentally, SNaseΔ is known to be partially unfolded. However, in simulations over 1 ns at 300 K and over 500 ps at 400 K, SNaseΔ remains stable in the native‐like folded conformation, the salt bridge hindering unfolding. When the potential function is altered so as to selectively weaken the salt bridge, which then breaks rapidly at 430 K, the protein starts to unfold. The results suggest that breaking of this salt bridge presents a significant barrier to the unfolding transition of SNaseΔ from a native‐like state to the unfolded state. Potential of mean force calculations indicate that the barrier height for this transition is ∼7 kcal/mol. Proteins 2003;50:507–515. © 2003 Wiley‐Liss, Inc.
Hypoglycaemic effect of Opuntia lindheimeri Englem. in a diabetic pig model
Authors: Laurenz Jamie C. , Collier Chad C. , Kuti Joseph O.
Published: January 2003

The hypoglycaemic activity of Opuntia lindheimeri Englem. was investigated in non‐diabetic (control pigs) and streptozotocin‐induced diabetic pigs using an enteral (oral) route of administration. Following the administration of O. lindheimeri extract (0, 250 or 500 mg/kg body weight), blood glucose concentrations in control pigs fluctuated around initial baseline concentrations, but were not consistently affected by either the dose of O. lindheimeri or by the time following administration. In contrast, administration of O. lindheimeri extract to STZ‐treated pigs resulted in both a dose‐ (p < 0.001) and time‐dependent (p < 0.001) decrease in blood glucose concentrations. The hypoglycaemic effect of the extract was apparent within 1 h of administration, with maximal effects occurring at 4 h after administration. These results confirm the hypoglycaemic effect of O. lindheimeri extract in a diabetic pig model. In addition, given the physiological similarities of the pig to humans, this model will be of tremendous use in assessing the long‐term effects of Opuntia administration on the secondary problems associated with diabetes. Copyright © 2003 John Wiley & Sons, Ltd.
Antioxidant effect of polyamines on erythrocyte cell membrane lipoperoxidation after free‐radical damage
Authors: Farriol Mireia , Segovia‐Silvestre Toni , Venereo Yusimy , Orta Xavi
Published: January 2003

This in vitro study determined the effect of three doses each (100, 500 and 1000 μm) of putrescine, spermidine and spermine on malondialdehyde (MDA) release in red blood cells (RBCs) from healthy individuals after hydrogen peroxide stimulation (10 mM). Twenty‐two volunteers, 9 males and 13 females, aged 41.5 ± 16.4 years, were studied. MDA was measured by thiobarbituric reaction (TBARs) and the results were calculated using ϵ = 1.56 × 105. The analysis of variance (ANOVA) demonstrated a statistically significant overall decrease in MDA release in the polyamine‐exposed cells (p < 0.0001) when compared with unexposed cells. Individual analysis of each polyamine separately showed a 52% decrease in MDA release with added spermine and a 39.5% decrease with added spermidine (p < 0.001). No evaluable effect was found for putrescine. There was no correlation between the effect produced and the three doses of spermidine or spermine added, indicating a non dose‐dependent action. Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacological activity of South American plants: effects on spontaneous in vivo lipid peroxidation
Authors: Desmarchelier Cristian J. , de Moraes Barros Silvia B.
Published: January 2003

The in vivo protective effects of methanol extracts of eight South American medicinal plants traditionally used as antiinflammatory were determined by means of spontaneous lipid peroxidation of liver tissue in rats. The production of TBARS was reduced in a dose dependent manner for A. macrocarpa (IC50 = 132 mg/kg), A. urundeuva (IC50 = 176 mg/kg), C. reticulata (IC50 = 561mg/kg) and S. obtusifolium (IC50 = 918 mg/kg). The extracts of P. peltata and U. tomentosa were only effective at a high concentration (300 mg/kg), although these values were not significant. The lyophilized latex of C. lechleri decreased the production of TBARS at a 200 mg/kg dose, although pro‐oxidant effects were observed at lower doses (50 mg/kg). The extract of H. pallida was pro‐oxidant at lower concentrations (50 mg/kg). Copyright © 2003 John Wiley & Sons, Ltd.