bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrolysis‐improved thermosensitive polyorganophosphazenes with α‐amino‐ω‐methoxy‐poly(ethylene glycol) and amino acid esters as side groups
Authors: Lee Sang Beom , Song Soo‐Chang
Published: May 2005

A series of hydrolysis‐improved thermosensitive polyorganophosphazenes with α‐amino‐ω‐methoxy‐poly(ethylene glycol) (AMPEG) and amino acid esters (AAEs) of ‘N,N‐systems’ was synthesized, and their properties were evaluated in comparison with the thermosensitive polyorganophosphazenes with methoxy‐poly(ethylene glycol) (MPEG) and AAEs of ‘O,N‐systems’, by means of 31P NMR spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Most of the present polymers showed a lower critical solution temperature (LCST) in the range 32.0–79.0 °C, depending on the kinds of AAE, length of AMPEG and the mol ratio of the two substituents. These polymers exhibited higher LCSTs and faster degradation rates than the MPEG‐based polymers. The aqueous solution of poly(ethyl glycinate phosphazene)‐graft‐poly(ethylene glycol) [NP(GlyEt)0.94(AMPEG350)1.06]n did not show an LCST, which is presumed to be due to its high hydrophilicity, in contrast to [NP(GlyEt)1.01(MPEG350)0.99]n which showing an LCST at 77.5 °C. On the other hand, the polymers with a high content of AAE or with hydrophobic amino acids such as L‐aspartic acid and L‐glutamic acid, have shown a similar LCST to those of the MPEG‐based polymers. The half‐lives (t1/2) for hydrolysis of [NP(AMPEG350)1.06(GlyEt)0.94]n at pH 5, 7.4 and 10 were 9, 16, and 5 days, respectively, which are almost 2.5 to 4 times faster than that of the MPEG‐based polymers. The LCST of the present N,N‐polymers has been shown to be more influenced by salts such as NaCl (‘salting‐out’ effect) and tetrapropylammonium bromide (TPAB) (‘salting‐in’ effect) compared with the ‘O,N‐system’. Such differences of the ‘N,N‐systems’ from the ‘O,N‐systems’ in thermosensitivity, hydrolysis behavior and salt effect seem to be due to the higher hydrophilicity of the amino group in AMPEG. Copyright © 2005 Society of Chemical Industry
Comparison of protein and peptide prefractionation methods for the shotgun proteomic analysis of Synechocystis sp. PCC 6803
Authors: Gan Chee Sian , Reardon Kenneth F. , Wright Phillip C.
Published: May 2005

Proteome analysis by gel‐free “shotgun” proteomics relies on the simplification of a peptide mixture before it is analyzed in a mass spectrometer. While separation on a reverse‐phase (RP) liquid chromatographic column is widely employed, a variety of other methods have been used to fractionate both proteins and peptides before this step. We compared six different protein and peptide fractionation workflows, using Synechocystis sp. PCC 6803, a useful model cyanobacterium for potential exploitation to improve its production of hydrogen and other secondary metabolites. Pre‐digestion protein separation was performed by strip‐based isoelectric focusing, one‐dimensional polyacrylamide gel electrophoresis, or weak anion exchange chromatography, while pre‐RP peptide separation was accomplished by isoelectric focusing (IEF) or strong cation exchange chromatography. Peptides were identified using electrospray ionization quadrupole time of flight‐tandem mass spectrometry. Mass spectrometry (MS) and tandem mass spectra were analyzed using ProID software employing both a single organism database and the entire NCBI non‐redundant database, and a total of 776 proteins were identified using a stringent set of selection criteria. Method comparisons were made on the basis of the results obtained (number and types of proteins identified), as well as ease of use and other practical aspects. IEF‐IEF protein and peptide fractionation prior to RP gave the best overall performance.
Lethal and sub‐lethal effects of spinosad on bumble bees (Bombus impatiens Cresson)
Authors: Morandin Lora A , Winston Mark L , Franklin Michelle T , Abbott Virginia A
Published: May 2005

Recent developments of new families of pesticides and growing awareness of the importance of wild pollinators for crop pollination have stimulated interest in potential effects of novel pesticides on wild bees. Yet pesticide toxicity studies on wild bees remain rare, and few studies have included long‐term monitoring of bumble bee colonies or testing of foraging ability after pesticide exposure. Larval bees feeding on exogenous pollen and exposed to pesticides during development may result in lethal or sub‐lethal effects during the adult stage. We tested the effects of a naturally derived biopesticide, spinosad, on bumble bee (Bombus impatiens Cresson) colony health, including adult mortality, brood development, weights of emerging bees and foraging efficiency of adults that underwent larval development during exposure to spinosad. We monitored colonies from an early stage, over a 10‐week period, and fed spinosad to colonies in pollen at four levels: control, 0.2, 0.8 and 8.0 mg kg−1, during weeks 2 through 5 of the experiment. At concentrations that bees would likely encounter in pollen in the wild (0.2–0.8 mg kg−1) we detected minimal negative effects to bumble bee colonies. Brood and adult mortality was high at 8.0 mg kg−1 spinosad, about twice the level that bees would be exposed to in a ‘worst case’ field scenario, resulting in colony death two to four weeks after initial pesticide exposure. At more realistic concentrations there were potentially important sub‐lethal effects. Adult worker bees exposed to spinosad during larval development at 0.8 mg kg−1 were slower foragers on artificial complex flower arrays than bees from low or no spinosad treated colonies. Inclusion of similar sub‐lethal assays to detect effects of pesticides on pollinators would aid in development of environmentally responsible pest management strategies. Copyright © 2005 Society of Chemical Industry
A gauge invariant approach to the Raman scattering in heavily doped crystals
Authors: Klochikhin A. A. , Davydov V. Yu. , Emtsev V. V. , Smirnov A. N. , Baltz R. v.
Published: May 2005

A gauge invariant approach to the Raman scattering from L––LO–L+ modes in heavily doped n‐type semiconductors is developed. Sum rules expressing the charge conservation of electrons and ions are established for the allowed scattering mechanism (deformation potential and interband Fröhlich interactions), forbidden mechanism (intraband Fröhlich + Coulomb interactions), and the mechanism of charge density fluctuations. Impurity induced Raman processes for all three mechanisms are considered. Our predictions agree well with new experimental data on GaAs, GaN, and InN crystals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐organization of cadmium sulfide nanoparticles on the macroscopic scale
Authors: Rempel Andrej A. , Kozhevnikova Natalia S. , Van den Berghe Sven , Van Renterghem Wouter , Leenaers Ann J. G.
Published: May 2005

A self‐organization of chemical bath deposited cadmium sulfide colloidal particles into well shaped hexagonal prisms of nearly the same size in a micrometer range is found. The self‐organization phenomenon itself and the size of resulting prisms depend on the chemical affinity of the deposition reaction. In spite of the nearly perfect shape, the inner structure of the CdS colloidal crystals is highly disordered and has at least two hierarchy levels. On the scale of scanning electron microscopy, the loose and disordered microstructure of the colloidal crystals consists of nonuniformly shaped coagulates, with sizes between 150 and 250 nm. Transmission electron microscopy shows that the coagulates are polycrystals with large angle boundaries between nonuniformly shaped grains with an average size of 7 ± 2 nm. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prediction of a high‐density phase of SiO2 with a high dielectric constant
Authors: Ouyang Lizhi , Ching Wai‐Yim
Published: May 2005

We have studied a cubic phase of SiO2 with an inverse‐Ag2O‐type structure by first‐principles calculations based on density functional theory. The electronic structure, dielectric, mechanical, and thermodynamic properties of this cubic phase are studied in detail. Our calculations show that this cubic phase composed of corner‐shared SiO4 units has a density of 3.6–3.7 g/cm, higher than any known tetrahedrally‐coordinated SiO2 phases (cf. Devine et al. [1]). It also has high optical and static dielectric constants of 3.34 and 9.73, respectively. Moreover, its lattice constant differs by only 1–2% from Si(100) surfaces, making it a suitable candidate for a defect free Si/SiO2 superlattice. The calculated phonon dispersion demonstrates that the structure is at least locally stable. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Changes in soil C‐isotopic composition in an agroecosystem under Free Air Carbon dioxide Enrichment (FACE) treatment during a crop rotation period
Authors: Giesemann Anette
Published: May 2005

FACE (Free Air Carbon dioxide Enrichment) has been used since 1999 to evaluate the effects of future atmospheric CO2 concentrations on an arable crop agroecosystem. The experiment conducted at the Institute of Agroecology at the Federal Research Centre in Braunschweig consists of a typical local crop rotation of winter barley, a cover crop, sugar beet and winter wheat. The atmospheric CO2 concentration of ambient air is about 375 ppm with a δ13C value of −7 to −9‰, and 550 ppm (δ13C value = −20.2‰) during daylight hours in the rings fumigated with additional CO2. Thus, the surplus C can be traced in the agricultural system. Over the course of the first experimental period (3‐year crop rotation period), the C‐isotopic composition and the C concentration in soil were monitored monthly. Plant samples were analysed according to the relevant developmental stages of the crop under cultivation. A 13C depletion was observed in plant parts, as well as in soil samples from the FACE rings under CO2 enrichment, indicating that labelled C has reached both respective ecosystem compartments. Albeit farming management practice (especially ploughing) leads to a mixing of ‘old’ and ‘new’ C compounds throughout all soil horizons down to the end of the ploughing layer and resulted in a heterogeneous distribution of newly formed C compounds in the soil, isotope analysis of soil C reflected where the surplus C went. Copyright © 2005 John Wiley & Sons, Ltd.
Post‐photosynthetic fractionation of stable carbon isotopes between plant organs—a widespread phenomenon
Authors: Badeck Franz‐W. , Tcherkez Guillaume , Nogués Salvador , Piel Clément , Ghashghaie Jaleh
Published: May 2005

Discrimination against 13C during photosynthesis is a well‐characterised phenomenon. It leaves behind distinct signatures in organic matter of plants and in the atmosphere. The former is depleted in 13C, the latter is enriched during periods of preponderant photosynthetic activity of terrestrial ecosystems. The intra‐annual cycle and latitudinal gradient in atmospheric 13C resulting from photosynthetic and respiratory activities of terrestrial plants have been exploited for the reconstruction of sources and sinks through deconvolution by inverse modelling. Here, we compile evidence for widespread post‐photosynthetic fractionation that further modifies the isotopic signatures of individual plant organs and consequently leads to consistent differences in δ13C between plant organs. Leaves were on average 0.96‰ and 1.91‰ more depleted than roots and woody stems, respectively. This phenomenon is relevant if the isotopic signature of CO2‐exchange fluxes at the ecosystem level is used for the reconstruction of individual sources and sinks. It may also modify the parameterisation of inverse modelling approaches if it leads to different isotopic signatures of organic matter with different residence times within the ecosystems and to a respiratory contribution to the average difference between the isotopic composition of plant organic matter and the atmosphere. We discuss the main hypotheses that can explain the observed inter‐organ differences in δ13C. Copyright © 2005 John Wiley & Sons, Ltd.
Choice of dietary protein of vegetarians and omnivores is reflected in their hair protein 13C and 15N abundance
Authors: Petzke Klaus J. , Boeing Heiner , Metges Cornelia C.
Published: May 2005

Stable isotopic (15N, 13C) composition of tissues depends on isotopic pattern of food sources. We investigated whether the isotopic compositions of human hair protein and amino acids reflect the habitual dietary protein intake. Hair samples were analyzed from 100 omnivores (selected randomly out of the 1987–1988 German nutrition survey VERA), and from 15 ovo‐lacto‐vegetarians (OLV), and from 6 vegans recruited separately. Hair bulk and amino acid specific isotopic compositions were analyzed by isotope‐ratio mass spectrometry (EA/IRMS and GC/C/IRMS, respectively) and the results were correlated with data of the 7 day dietary records. Hair bulk 15N and 13C abundances clearly reflect the particular eating habits. Vegans can be distinguished from OLV and both are significantly distinct from omnivores in both 15N and 13C abundances. 15N and 13C abundances rose with a higher proportion of animal to total protein intake (PAPI). Individual proportions of animal protein consumption (IPAP) were calculated using isotopic abundances and a linear regression model using animal protein consumption data of vegans (PAPI = 0) and omnivores (mean PAPI = 0.639). IPAP values positively correlated with the intake of protein, meat, meat products, and animal protein. Distinct patterns for hair amino acid specific 15N and 13C abundances were measured but with lower resolution between food preference groups compared with bulk values. In conclusion, hair 13C and 15N values both reflected the extent of animal protein consumption. Bulk isotopic abundance of hair can be tested for future use in the validation of dietary assessment methods. Copyright © 2005 John Wiley & Sons, Ltd.
Gas‐phase positive ion chemistry of 1‐bromo‐1‐chloro‐2,2,2‐trifluoroethane (halothane) upon electron ionization within an ion trap mass spectrometer
Authors: Marotta Ester , Scorrano Gianfranco , Paradisi Cristina
Published: May 2005

The positive ion chemistry occurring within an ion trap mass spectrometer upon electron ionization of 1‐bromo‐1‐chloro‐2,2,2‐trifluoroethane, the important anaesthetic halothane, has been mapped by means of collision‐induced decomposition and ion/molecule self‐reaction experiments. Ionized halothane (M+.) reacts with neutral halothane to form the ionized olefin [ClBrCCF2]+. via HF elimination. Among the ionic fragments, [M–Br]+ and [M–F]+ react with halothane via chloride abstraction while [M–Cl]+ is unreactive under the same experimental conditions. Substituted methyl cations CHFX+ and CF2X+ (X = F, Cl, Br) undergo halide transfer processes, their reactivity being highest for X = F. Ionized carbenes CXY+ (X,Y = F,F; H,Br; H,Cl; H,F) react with halothane to form CClXY+ and CBrXY+, whereas CF+ inserts into the CCl bond to form CF and CClF. Finally, Br+ and Cl+ react with halothane by charge transfer. Collision‐induced dissociation experiments disclosed interesting rearrangements involved in the dissociations of +CHX‐CF3 ions (X = Br, Cl), which undergo fluorine migration and elimination of CF2, as already observed for +CCl2‐CF3 in a previous investigation. Copyright © 2005 John Wiley & Sons, Ltd.
δ34S measurements on organic materials by continuous flow isotope ratio mass spectrometry
Authors: Yun Misuk , Mayer Bernhard , Taylor Stephen W.
Published: May 2005

Sulfur (S) isotope ratios of thoroughly dried organic samples were measured by direct thermal decomposition in an elemental analyzer coupled to an isotope ratio mass spectrometer in continuous flow mode (EA‐CF‐IRMS). For organic samples of up to 13 mg weight and with total S contents of more than 10 μg, the reproducibility of the δ34Sorganic values was ±0.4‰ or better. However, the δ34S values of organic samples measured directly by online EA‐CF‐IRMS analysis were between 0.3 and 2.9‰ higher than those determined on BaSO4 precipitates produced by Parr Bomb™ oxidation from the same sample material. Our results suggest that structural oxygen in organic samples influences the oxygen isotope ratios of the SO2 produced from organic samples. Consequently, SO2 generated from organic samples appears to have different 18O/16O ratios than SO2 generated from BaSO4 precipitates and inorganic reference materials, resulting in a deviation from the true δ34S values because of 32S16O18O contributions to mass 66. It was shown that both the amount of structural oxygen in the organic sample, and the difference of the oxygen isotope ratios between organic samples and tank O2, influenced the magnitude of the observed deviation from the true δ34S value after direct EA‐CF‐IRMS analysis of organic samples. Suggestions are made to correct the difference between measured δ34Sorganic and true δ34S values in order to obtain not only reproducible, but also accurate S isotope ratios for organic materials by EA‐CF‐IRMS. Copyright © 2005 John Wiley & Sons, Ltd.
A novel approach to identify plant parasitic nematodes using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Perera Modika R. , Vanstone Vivien A. , Jones Michael G. K.
Published: May 2005

Plant parasitic nematodes are difficult to identify because different species are morphologically similar, and this makes their control more difficult. The aim of this work was to develop a rapid, simple method to identify plant parasitic nematodes, based on analysis of protein profiles of nematodes generated by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). Two methods have been used: grinding and direct analysis of intact nematodes. Both methods were standardised using the nematode Anguina tritici (wheat seed‐gall nematode) as a model. Development of the approach involved optimisation of experimental parameters to generate reproducible diagnostic protein profiles for plant parasitic nematodes. With α ‐cyano‐4‐hydroxycinnamic acid (CHCA) as the matrix, the most effective solvent extraction was with 90% acetone. With sinapinic acid (SA) as matrix, 90% ethanol was most effective. When intact nematodes were analysed directly by mixing with the matrix solution, 40 min extraction with CHCA matrix solution generated the best protein profiles. The standardised methods were applied to analyse the seed‐gall nematodes A. tritici and A. funesta and to the root‐knot nematode, Meloidogyne javanica, which infects many horticultural crops. Typical protein profiles and diagnostic peaks were identified for these nematode species and for mixtures of Anguina species. The results provide ‘proof‐of‐concept’ that these nematode species can be identified by protein profiling using MALDI‐TOFMS. This new approach could be extended to identify other plant and non‐plant parasitic nematodes. Copyright © 2005 John Wiley & Sons, Ltd.
Automated accurate mass data processing using a gas chromatograph/time‐of‐flight mass spectrometer in drug discovery
Authors: Petucci Chris , Mallis Larry
Published: May 2005

A gas chromatograph/time‐of‐flight (GCT) mass spectrometer, with high mass measurement accuracy to within 5 ppm, has been used for the automated accurate mass analysis of multicomponent mixtures and drug discovery compounds. A multicomponent mixture was analyzed several times over the course of a week to assess the reproducibility and ruggedness of the automated method while operating the GCT in electron ionization mode. For example, the data for 31 radical cations generated via electron ionization was processed using automated software (i.e. OpenLynx™) to provide for mass accuracies less than 5 ppm for nearly 100% of the ions from multiple injection data. Mass accuracies of the radical anions of polyaromatic hydrocarbons generated via negative chemical ionization, and protonated pyridines and quinolines generated via methane chemical ionization, were mainly less than 5 ppm from multiple injection data. In addition, the automated method has been used for the accurate mass analysis of drug discovery compounds. Copyright © 2005 John Wiley & Sons, Ltd.
Photocatalytic degradation of the herbicide isoproturon: characterisation of by‐products by liquid chromatography with electrospray ionisation tandem mass spectrometry
Authors: Amorisco A. , Losito I. , Palmisano F. , Zambonin P. G.
Published: May 2005

By‐products arising from immobilised TiO2‐catalysed photodegradation of the herbicide isoproturon [3‐(4‐isopropylphenyl)‐1,1‐dimethylurea] in aqueous solution under solar radiation were analysed by reversed‐phase liquid chromatography combined with electrospray ionisation ion trap mass spectrometry. Structural information on by‐products, formed at different degradation times, was then obtained from interpretation of the relevant MS/MS spectra. Several species were identified through this approach, and in many cases several isomers were found. As expected, most by‐products resulted from single or multiple hydroxylation (by photo‐generated OH. radicals) of the isoproturon molecule at different positions. However, substitution of some functional groups of the herbicide (isopropyl or methyl) by OH. was also observed. A possible degradation scheme is hypothesised. Copyright © 2005 John Wiley & Sons, Ltd.
Characterization of oligosaccharide moieties of glycopeptides by microwave‐assisted partial acid hydrolysis and mass spectrometry
Authors: Lee Bao‐Shiang , Krishnanchettiar Sangeeth , Lateef Syed Salman , Gupta Shalini
Published: May 2005

Microwave‐assisted partial acid hydrolysis and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry were used to study oligosaccharide structures of glycopeptides. Tryptic N‐glycosylated peptides of horseradish peroxidase, with MH+ ions at m/z 2533, 2612, 3355, 3673, and 5647, were used as test cases. Within a microwave exposure with trifluoroacetic acid of 2 min, partial cleavages of the oligosaccharides of these tryptic N‐glycosylated peptides were observed. The data showed that the most labile group within the oligosaccharides is the fucose (Fuc) residue, and that a majority of the end cleavage products are peptides with one N‐acetylglucosamine (GlcNAc) residue linked to asparagine (Asn). In addition, the glycopeptides with m/z 3355 and 3673 carry an oligosaccharide (Xyl)Man3(Fuc)GlcNAc2, the glycopeptide at m/z 5647 carries two oligosaccharides (Xyl)Man3(Fuc)GlcNAc2, and the glycopeptides at m/z 2612 and 2533 carry (Xyl)Man3GlcNAc2 and (Fuc)GlcNAc, respectively. However, the glycosylation site of the m/z 2612 peptide at Asn286 is partially occupied. This simple and rapid method is particularly useful in identifying glycopeptides and obtaining monosaccharide compositions of glycopeptides. Copyright © 2005 John Wiley & Sons, Ltd.
Short‐term dynamics of slurry‐derived plant and microbial sugars in a temperate grassland soil as assessed by compound‐specificδ13C analyses
Authors: Sauheitl Leopold , Glaser Bruno , Bol Roland
Published: May 2005

In view of recent discussions about climate change and the anthropogenically enhanced greenhouse effect, the aim of this study was to determine the short‐term carbon (C) dynamics in a grassland soil after slurry application. It is known that, depending on cultivation practices, agro‐ecosystems can act either as sources or as sinks for atmospheric CO2. C3 and C4 slurries were applied, differing in their stable C isotope signature, to be able to differentiate between native (soil‐inherent) and fresh (slurry‐applied) C. Samples were taken from 0–2, 2–7.5 and 7.5–15 cm soil depths from 90 days before until 4 weeks after slurry application at various intervals. We carried out compound‐specific stable isotope analysis (CSIA) of plant‐ (arabinose and xylose) and microbial‐derived sugars (fucose and rhamnose). Up to 45% of the applied slurry‐derived xylose was found in the 0–2 cm soil depth within 24 h after slurry application, with this figure decreasing rapidly and then increasing again towards the end of the experiment. Therefore, during the first phase of slurry incorporation, preferentially the soluble part of slurry entered the first 2 cm of soil while, after about 2 weeks, particulate slurry‐derived organic matter was incorporated into the soil. The ratio between plant‐ and microbial‐derived sugars together withδ13C values of individual sugars in the 2–7.5 cm soil depth revealed that the dissipation of sugars from the 0–2 cm soil depth was not only due to leaching, but also was caused by microbial degradation of the fresh C because slurry did not contain significant amounts of rhamnose while theδ13C values of rhamnose became progressively enriched in13C during the experiment. Stable isotope measurements of bulk soil previously only showed significant differences between C4 and C3 plots at 0–2 cm soil depth. The CSIA of the individual sugars was much more sensitive than bulk isotope measurements, revealing significant differences between C4 and C3 plots even at the 2–7.5 cm soil depth during the first phase of the experiment. Additionally, the dynamics of slurry‐derived plant and microbial sugars could be followed specifically. Copyright © 2005 John Wiley & Sons, Ltd.
Giving priority to evidence in science teaching: A first‐year elementary teacher's specialized practices and knowledge
Authors: Avraamidou Lucy , Zembal‐Saul Carla
Published: May 2005

The purpose of this qualitative case study was to examine the nature of a first‐year elementary teacher's specialized practices and knowledge for giving priority to evidence in science teaching and to explore the possible sources from which this knowledge was generated. Data included three audiotaped interviews, six videotaped classroom observations, lesson plans, and samples of students' work. The findings of this study reveal that the teacher gave priority to evidence by frequently engaging students in collecting evidence through observations and investigations, recording and representing evidence, and using that evidence to construct explanations. The findings of this study also illustrate that critical experiences during preparation to teach and specific university coursework acted as sources through which the teacher's specialized knowledge for giving priority to evidence was generated. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 965–986, 2005
Levels of microcystins in two argentinean reservoirs used for water supply and recreation: Differences in the implementation of safe levels
Authors: Conti Ana Laura Ruibal , Guerrero José María , Regueira Jose María
Published: May 2005

Toxic cyanobacterial blooms are an increasing problem in Argentina. The production of cyanobacterial hepatotoxins (microcystins) and their presence in drinking and recreational waters represent a growing danger to human and animal health. Risk management deals with the probability that a certain exposure to toxins will lead to specific health outcomes. Various model schemes for risk management have been portrayed, most of which have some common elements. These include the need for an information base on which to make decisions. Thus, seasonal variability in the concentrations of total microcystins and cyanobacterial cells was studied in two reservoirs: San Roque and Paso de las Piedras. Both reservoirs are eutrophic water bodies and mainly used to supply drinking water and for recreation. Because San Roque is an important recreational spot, the spatial distribution of microcystins was also investigated. Sampling of the San Roque Reservoir occurred from 1998 to 2000 and of the Paso de las Piedras Reservoir from June to December 2002 (late autumn, winter, and spring). Microcystins were identified by LC‐MS, and their concentrations were measured using the enzyme‐linked immunosorbent assay. These hepatotoxic compounds were detected in all seasons, and even during winter relatively high concentrations were observed. Concentrations in the San Roque Reservoir varied from undetectable to 920 μg/L. On the contrary, in the Paso de las Piedras Reservoir the concentration remained below 1 μg/L, which is the provisional guideline value proposed by the World Health Organization (WHO; Chorus and Bartram, 1999) for microcystin‐LR in drinking water. Comparison of cell number and concentration of total microcystins indicated that the phytoplankton in San Roque Reservoir contained more toxic cyanobacterial strains than did the Paso de las Piedras Reservoir. This indicates that the threshold of 2000 cell/mL proposed by WHO as a alert level should be adjusted: it should be reduced for the San Roque Reservoir, whereas it seems appropriate for the Paso de la Piedras Reservoir. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 263–269, 2005.
Screening for trisomy 21 in monochorionic twins by measurement of fetal nuchal translucency thickness
Authors: Vandecruys H. , Faiola S. , Auer M. , Sebire N. , Nicolaides K. H.
Published: May 2005

Objective

To determine whether in screening for trisomy 21 by measurement of fetal nuchal translucency (NT) thickness in monochorionic twin pregnancies it is preferable to use the higher, smaller or average NT.

Methods

We retrospectively examined 769 monochorionic twin pregnancies that had undergone NT screening. The selection criteria were that first, in each pregnancy both fetuses were alive at the 11 to 13 + 6‐week scan and second, the fetal karyotype had been determined by prenatal invasive testing or the pregnancy outcome was known. In each pregnancy the risk for trisomy 21 was calculated by a combination of maternal age and fetal NT for crown–rump length (CRL). Three estimates of risk for each pregnancy were made using the higher, smaller and average NT and these were compared for detection and false positive rates.

Results

The median maternal age was 33 (range, 16–45) years, the CRL was 62 (range, 45–84) mm and gestational age was 12 (range, 11 to 13 + 6) weeks. Either the fetal karyotype was normal, or phenotypically normal babies were born, in 761 cases. The karyotype was abnormal in eight cases, including six with trisomy 21. The estimated risk using the higher, smaller and average NT was 1 in 300 or more in 6 (100%), 4 (66.7%) and 6 (100%) of the trisomy 21 pregnancies and in 148 (19.4%), 57 (7.5%) and 106 (13.9%) of the normal pregnancies. For a detection rate of 100%, the false positive rates using the higher, smaller and average NT would be 5.1%, 45.9% and 4.2%, respectively.

Conclusion

In monochorionic twins, effective screening for trisomy 21 is best provided by using the average NT measured in the two fetuses. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Drugs for peptic ulcer
Authors: Clark Charles G. , Wyllie John H.
Published: May 2005

Conservative management of peptic ulcer relies on the use of drugs as an adjuvant to the time‐honored measures of avoiding stress, reducing gastric secretion, and regulating the diet. Alkalies neutralize acid and anticholinergic drugs partly inhibit secretion. Both are widely used but are often inadequate to control symptoms. Carbenoxolone appears to have a more specific effect in promoting healing of gastric ulcers and has now been used for 15 years. Its role in the treatment of gastric ulcer can be critically examined, particularly in relation to how this influences surgical management. Recently introduced compounds known as histamine H2‐receptor antagonists have a profound effect in inhibiting gastric secretion. Early experience in patients with duodenal ulcer indicates the efficacy of these compounds in promoting healing. These potent new drugs are likely to influence strongly the management of patients with duodenal ulcer, and this may affect the indications for surgery.
Review of elective surgical treatment of chronic duodenal ulcer
Authors: Feldman Stephen D. , Wise Leslie , Ballinger Walter F.
Published: May 2005

This article is a review of 20 clinical trials of various forms of elective surgical treatment of chronic duodenal ulcer conducted between 1964 and 1975, some of them prospective and others retrospective in nature. Comparisons have been made of the results following truncal vagotomy with drainage, truncal vagotomy with antrectomy, and partial gastrectomy. Additionally, selective vagotomy and truncal vagotomy have been compared in some studies and various forms of drainage, such as pyloroplasty and gastrojejunostomy, have been compared in others. In general, the results of all current forms of elective surgery for chronic duodenal ulcer have been very good, and the differences among the effects of the various procedures have been small. There have been no significant differences in the mortality rates associated with the several operations when they have been performed electively. The rate of ulcer recurrence and incidence of diarrhea have been somewhat higher after truncal vagotomy with drainage, whereas the frequency of dumping and amount of weight loss have been somewhat greater after all forms of gastric resection. Selective vagotomy appears to be associated with less frequent and severe diarrhea than does truncal vagotomy. There have been no apparent differences in the results of the various drainage procedures that have been combined with vagotomy. Highly selective vagotomy without drainage, the most recent operation for duodenal ulcer, has resulted in the lowest incidence of post‐operative side effects of any surgical procedure in current use. However, the frequency of ulcer recurrence after this therapeutic measure remains to be determined by long‐term studies.
Parietal cell (highly selective or proximal gastric) vagotomy for peptic ulcer disease
Authors: Amdrup Erik , Andersen Daniel , Jensen Hans ‐Eric
Published: May 2005

Parietal cell vagotomy has been in clinical use for 7 years in elective treatment of nonobstructive duodenal ulcer, and for even a shorter period for complicated cases and for gastric ulcer. The evolution of the surgical technique has not yet come to an end and the ability to perform the procedure is still improving. It can therefore be questioned, if this operation is yet ripe for a realistic clinical trial, and the great variation in recurrence rate reported in pilot series as well as in prospective randomized clinical trials points to the possibility that we will have to wait several years before the anticipated mean recurrence rate is known. At present it can be stated that even if gastric emptying is not quite undisturbed, the addition of a drainage procedure in nonobstructive cases is unnecessary. The same may be true in some patients with pyloric obstruction. Furthermore, the mortality rate is very low and the incidence of moderate‐to‐severe dumping and diarrhea is virtually nil.
Surgery for gastric ulcer
Authors: Duthie Herbert L.
Published: May 2005

Despite the initial healing achieved by medical treatment with carbenoxolone, surgery is frequently needed in the management of gastric ulcer. We have studied 150 patients over the past 10 years in an attempt to define the place of conservative surgery compared with the standard partial gastrectomy of the Billroth I type. Functional results have not been significantly different and the individual surgeon's choice will depend on his philosophy with regard to the risk of cancer in the postoperative stomach, and his technical expertise with the newer kinds of vagotomy. To my mind it is perfectly justifiable to use highly selective vagotomy with excision of the ulcer to treat gastric ulcer alone, especially if the patient is one in whom postgastrectomy symptoms could be disabling. Further follow‐up is needed to decide whether it should replace partial gastrectomy as the standard procedure.
Progress in the treatment of acute gastroduodenal mucosal lesions (AGML)
Authors: Speranza Vincenzo , Basso Nicola
Published: May 2005

This article presents an analysis of acute gastroduodenal mucosal lesions (AGML) based on a review of current literature and the personal experience of the authors. The pathology of AGML involves two distinct types of lesions, namely, superficial erosions confined to the acid‐secreting gastric mucosa and presenting as erosive hemorrhagic gastritis, and acute ulcers that occur in the alkaline gastric mucosa and duodenum. The etiology of these two lesions is very likely different. Acute gastroduodenal ulcers, best known as stress ulcers, are probably “peptic” lesions, whereas erosive hemorrhagic gastritis appears to be due to pathologic back diffusion of hydrogen ions caused by a breakdown of the gastric mucosal barrier as a result of endogenous factors, such as gastric mucosal ischemia, and sometimes exogenous factors, such as alcohol, urea, and acetylsalicylic acid. Catecholamine hypersecretion resulting from severe stress, such as occurs in hypovolemia, sepsis, and hypercapnea, contributes to ischemia of the gastric mucosa by producing splanchnic vasoconstriction. The key to the diagnosis of AGML is early endoscopy in all cases of upper gastrointestinal bleeding. Therapy for AGML should begin with a trial of medical measures directed at restoring effective perfusion of tissues and removing hydrogen ions from the stomach by gastric washing. Medical therapy is effective in 80% of patients with erosive hemorrhagic gastritis, but surgical treatment is usually required in acute gastroduodenal ulcer. When surgery is necessary for either type of lesion, vagotomy with hemigastrectomy appears to be the most effective operation. The personal experience of the authors has involved 36 patients with AGML who were treated in three periods between 1968 and 1976. The mortality rate of patients with AGML has been reduced from 50% in the first 2 years to zero in the last 2 years by the use of emergency endoscopy for diagnosis, appropriate medical therapy, properly timed and executed surgery, and, most recently, selective angiography.
Geographical aspects of peptic ulcer surgery
Authors: Tovey Frank I.
Published: May 2005

The geographic distribution of duodenal ulcer and its characteristics in rural areas of high incidence in developing countries are reviewed. The choice of surgical procedures is discussed in light of the bulky diet and nutritional problems of these countries. A vagotomy procedure is advised for duodenal ulcer and a Billroth I gastrectomy for gastric ulcers of the body of the stomach.
Surgery of hemophiliacs—20 years' experience
Authors: Nilsson Inga Marie , Hedner Ulla , Ahlberg åke , Larsson S. Anders , Bergentz Sven ‐Erik
Published: May 2005

Seventy‐seven hemophilic patients of type A or type B were subjected to a total of 108 major surgical procedures mainly in the field of general surgery, orthopedic surgery, or neurosurgery. The principles for the substitution therapy in the different types of procedures and different types of hemophilic diseases are described, as well as the indications for surgery and the surgical technique. The importance of prolonged substitution therapy postoperatively to avoid late hematoma, particularly in patients with severe hemophilia undergoing major surgery, is stressed. With this type of management there has been no increased intraoperative hemorrhage, and very few cases of late hematoma formation. By combining the substitution therapy with immunosuppression, it has been possible to operate also on patients with inhibitors against factor VIII or IX. The rate of complications, particularly the incidence of hepatitis, has been low with the type of substitution given in this series of patients. It is concluded that major surgery can be carried out even in severe hemophilia without significantly increased risk. The handling of the substitution therapy, and the surgical judgment and technique, offers however, special problems, necessitating centralization of elective cases.
Isolation of viable human pancreatic islets
Authors: Ferguson John , Allsopp Roger H. , Taylor Ross M. R. , Johnston Ivan D. A.
Published: May 2005

This article reports a method for the isolation of viable pancreatic islets from the human pancreas. Isolated islets were obtained from human pancreata of cadavers, patients undergoing surgical operations, and fetuses, using a freehand microdissection procedure. Viability was assessed by light microscopy of sections stained with aldehyde fuchsin and by measuring the insulin output of islets in response to a glucose stimulus in vitro using a perifusion system. Ten pieces of cadaver pancreas were studied. Islets were isolated from 6 specimens and in 5 of these were shown to respond to a glucose stimulus in vitro. Histologically the islets showed minimal damage with slight degranulation of the beta cells. Five pieces of pancreas removed at operation were studied as well. Islets were isolated in all cases, but only 2 showed a response to a glucose stimulus. Pancreata from a 26‐week and 34‐week human fetus were also studied. It was not possible to microdissect islets from either case, but small pieces of pancreas from the 26‐week fetus were shown to respond to a glucose stimulus by producing a significant increase in insulin output.
Transsphenoidal microsurgery for selective removal of functional pituitary microadenomas
Authors: Nielson Karl D. , Watts Clark , Clark Kemp
Published: May 2005

The transsphenoidal approach to the pituitary gland is emerging as the safest and most efficacious procedure for the management of pituitary tumors. With the aid of the microscope large tumors producing visual symptoms can be removed and microadenomata producing only signs and symptoms of endocrinopathies can be safely and adequately approached. The procedure is described in this report. The results of its use in 29 patients with selected illustrative case reports are described.
Bronchobiliary fistula due to echinococcosis of the liver
Authors: Tierris Emmanuel J. , Avgeropoulos Kostas , Kourtis Kostas , Papaevangelou Evangelos J.
Published: May 2005

In Greece, which has the second highest incidence of echinococcosis in the world, there has been an overall decrease in the frequency of this disease and its complications during the past 15 years. Between 1920 and 1960, approximately 46 patients per year were operated on for echinococcosis at the Hellenic Red Cross Hospital, and 1.8% of 1037 hepatic hydatid cysts had ruptured into the bronchi. From 1960 to 1975, the number of patients requiring operation decreased to approximately 25 per year, and the incidence of rupture into the bronchi declined to 1% of 288 liver cysts. The reduction has resulted from improvements in preventive medicine and surgical care and a decrease in the frequency of infected cysts.

Bronchobiliary fistula is a serious complication of hydatid cyst of the liver and it must be treated surgically. A right thoracotomy or thoracoabdominal approach offers the possibility of dealing simultaneously with the hepatic cyst and the pulmonary lesions. The choice of operation depends on the findings and ranges from simple drainage of the hepatic cavity with division of the bronchobiliary communication, to resection of the lung (usually lobectomy) when a chronically infected pulmonary cavity is present. If a hydatid cyst of the liver ruptures simultaneously into the lung and the extrahepatic biliary tree with resultant obstruction of the common bile duct, unblocking of the common duct by evacuation of cysts and debris through a laparotomy takes priority over any other surgical action. Of 3 patients with bronchobiliary fistulas treated during the past 15 years, 2 were cured by simple drainage through a transabdominal approach.
Survival of patients with duodenal fistulas from necrotizing pancreatitis
Authors: Storm F. Kristian , Wilson Samuel E.
Published: May 2005

Acute necrotizing pancreatitis associated with occult duodenal necrosis and perforation developed in 3 patients 2 to 4 weeks after initially successful treatment of hemorrhagic pancreatitis. Exploration was required for fever, abdominal mass, or X‐ray findings of an intra‐abdominal abscess. At operation all pancreatic and retroperitoneal abscesses were drained with sump tubes, and the duodenal fistula was closed. An intraluminal tube, placed via a gastrostomy, was used for decompression of the duodenum. Postoperative management included total parenteral nutrition, antibiotics specific for aerobic and anaerobic flora, and frequent X‐rays to locate new intra‐abdominal abscesses. One to 4 reoperations were necessary because of continuing pancreatic necrosis and abscess formation in each patient. Necrotizing pancreatitis with unrelenting retroperitoneal sepsis and fistula formation results in serious morbidity, hospital stays of several months, and is now the major cause of death in patients with pancreatitis. Survival of all 3 patients resulted from drainage of evolving retroperitoneal abscesses and improvement in our technique for management of large duodenal fistulas.
Prevention of pulmonary embolism by inferior vena cava filters: Results in 62 cases
Authors: Schlosser Volker , Spillner G. , Kaiser W.
Published: May 2005

The most effective methods of preventing recurrent pulmonary embolism involve interruption of the pathway of emboli through the inferior vena cava. Of the several procedures that interrupt vena caval blood flow, percutaneous implantation of a screen filter is associated with the lowest risk and appears to be as effective as any of the other procedures in preventing recurrent emboli. This article describes the experience with 62 cases of screen filter implantation performed between 1971 and 1975. Pulmonary embolism recurred in 1.6% of the patients, and 10% of the patients developed swelling of the lower extremities that did not exist preoperatively. Inferior vena cava phlebography performed 6 to 24 months postoperatively in 25 patients showed a patent inferior vena cava in 9 patients, partial occlusion of the vena cava in 8 patients, and complete occlusion of the vena cava with extensive collateral veins in 8 patients.
Pathology of gastric cancer
Authors: Wanke M. , Schwan H.
Published: May 2005

This paper reviews the gross morphology, histologic classification, location, and modes of spread of gastric cancer. On the basis of gross appearance, we have classified gastric carcinoma into 4 types: (a) superficial spreading (6% of cases), (b) polypoid (11% of cases), (c) ulcerated (45% of cases), and (d) diffuse infiltrating (38% of cases). Our histologic classification includes 4 categories: (a) adenocarcinoma (70% of cases), (b) round cell carcinoma, (c) mucinous carcinoma, and (d) rare forms of carcinoma (squamous, adenoacanthoma, carcinosarcoma, collision tumor, ductogenic carcinoma). These main histologie categories are subdivided according to the degree of differentiation of each tumor. From 81 to 86% of gastric cancers arise in the pyloric region. Multifocal origin of stomach cancers occurs in about 10% of cases. The prognosis of gastric cancer depends on the extent of spread at the time of treatment. Intramural propagation beyond the grossly apparent margins is common, and extension into the duodenum and esophagus from lesions in the pylorus and cardia regularly occurs. Approximately 50% of gastric cancers infiltrate neighboring organs. Metastases to regional lymph nodes, particularly in the lesser curvature drainage area, occur in over half of the cases. Blood‐borne spread, to the liver and beyond, and peritoneal seeding are common.