bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a new multiple‐layer spotting technique for matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry of synthetic polymers
Authors: Meier Michael A. R. , Schubert Ulrich S.
Published: March 2003

A new multiple‐layer matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) sample‐spotting technique is described. This fast and easy technique was evaluated with poly(ethylene glycol) (PEG) standards and optimized conditions for these synthetic polymers were obtained. PEGs up to 35 kDa were detectable with this approach and single monomer resolution was observed up to 20 kDa. The spotting was performed using a multiple‐layer approach, which offers the capability of complex sample preparation without the requirement of premixing the different matrix, analyte and doping salt solutions. The technique reduces the time required for sample preparation and offers high flexibility with respect to sample composition and solvents utilized for the crystallization of the compounds. The technique is thus perfectly suited for applications in combinatorial material research. Copyright © 2003 John Wiley & Sons, Ltd.
Mass spectral studies of N,N‐dialkylaminoethanols
Authors: Reddy T. Jagadeshwar , Mirza Shama P. , Saradhi U. V. R. Vijaya , Rao V. Jayathirtha , Vairamani M.
Published: March 2003

Some dialkylaminoethanols, precursors of chemical warfare agents such as V‐agents and nitrogen mustards, were analyzed by electron impact (EI) and electrospray ionization (ESI) mass spectrometry. The fragmentation pathways in EI and ESI‐MS/MS methods are rationalized. The collision‐induced dissociation (CID) spectra of [M+H]+ ions of aminoethanols in ESI mode are clearly distinguishable from one another, including those of isomeric normal and branched chain dialkylaminoethanols. Structures can be proposed based on the general fragmentation pathways of these molecules. Copyright © 2003 John Wiley & Sons, Ltd.
Nitrogen purity influences the occurrence of As+ ions in high‐performance liquid chromatography/electrospray ionization mass spectrometric analysis of four common arsenosugars
Authors: Kuehnelt Doris , Goessler Walter , Francesconi Kevin A.
Published: March 2003

High‐performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC/ESI‐MS) can provide both elemental and molecular information and, therefore, is a very useful tool for the identification of arsenic compounds. When a method for the identification of four arsenosugars was employed in our laboratory with an HPLC/ESI‐MS system equipped with a Whatman model 75‐72 nitrogen generator, a signal at m/z 75 (As+) could not be observed. When the HPLC/ESI‐MS system was operated with nitrogen 5.0 (nitrogen of a purity of at least 99.999%) all four arsenosugars gave a signal at m/z 75. Because of this observation the influence of the quality of the nitrogen drying gas on the fragmentation of the four arsenosugars was systematically investigated. Standard solutions containing the four arsenosugars (0.5 ng As each) were separated on an anion‐exchange column and detected with ESI‐MS in the positive ion mode by monitoring the signals for [M+H]+, m/z 237, 91, and 75. Nitrogen with defined oxygen concentrations was used as drying gas. The purity of the nitrogen ranged from 99 to 99.999% (10 400 to 10 ppm oxygen impurity). The nitrogen with 99% purity gave no signal at m/z 75, but signals were obtained at m/z 91, 237, and for [M+H]+. When higher purity nitrogen (99.9%) was used, a signal was obtained at m/z 75, which accounted for 0.8–1.1% (depending on the kind of arsenosugar) of the sum of the signals for m/z 75, 91, 237 and [M+H]+. As the level of oxygen in the nitrogen decreased, the m/z 75 signal increased to 2.0–3.1%. This was accompanied by a concomitant decrease in the m/z 91 signal from 5.2–6.6% to 0.7–1.5%, whereas the signals for [M+H]+ and m/z 237 were essentially unchanged. Signals at m/z 75 with intensities comparable with those observed for the 99.9% pure nitrogen were also obtained for all the arsenosugars when the HPLC/ESI‐MS system was operated with a Domnick Hunter Nitrox UHPLCMS18 nitrogen generator. Dimethylarsinic acid, arsenobetaine, trimethylarsine oxide, arsenocholine and the tetramethylarsonium cation also gave no signal at m/z 75 when they were analyzed with the Whatman model 75‐72 nitrogen generator, but clear signals at m/z 75 were observed with the Domnick Hunter Nitrox UHPLCMS18 nitrogen generator. A nitrogen quality of at least 99.9% is required to obtain elemental information (m/z 75) when arsenic compounds are investigated by HPLC/ESI‐MS. Molecular and elemental information from one chromatographic run is a valuable tool for the characterization of unknown arsenic compounds. Copyright © 2003 John Wiley & Sons, Ltd.
Confirmatory analysis of β‐lactam antibiotics in kidney tissue by liquid chromatography/electrospray ionization selective reaction monitoring ion trap tandem mass spectrometry
Authors: Fagerquist Clifton K. , Lightfield Alan R.
Published: March 2003

Eleven β‐lactam antibiotics were analyzed in fortified and incurred beef kidney tissue using high‐performance liquid chromatography/electrospray ionization/selective reaction monitoring‐ion trap tandem mass spectrometry (LC/ESI‐SRM‐MSn). The analytes included: deacetylcephapirin, amoxicillin, cephapirin, desfuroylceftiofur cysteine disulfide (DCCD, a biomarker of ceftiofur), ampicillin, cefazolin, Pen G, oxacillin, cloxacillin, naficillin and dicloxicillin. Analytes were extracted with acetonitrile and water. Clean‐up was performed by solid‐phase extraction. Limits of confirmation in fortified tissue are as follows (tolerances or target levels in parentheses): deacetylcephapirin: 10–50 ng/g (100 ng/g); amoxacillin: 50–100 ng/g (10 ng/g); cephapirin: 10 ng/g (100 ng/g); DCCD: 500 ng/g (8000 ng/g); ampicillin: 10 ng/g (10 ng/g); cefazolin: 10 ng/g (10–50 ng/g); Pen G: 10 ng/g (50 ng/g); oxacillin: 10 ng/g (10–50 ng/g); cloxacillin: 10 ng/g (10 ng/g); naficillin: 10 ng/g (10–50 ng/g); dicloxacillin: 100–500 ng/g (10–50 ng/g). The present method was also tested on incurred kidney tissue that had previously been analyzed using a microbial assay. Good correspondence was found between the results from this new method and the bioassay. However, the present method is much more specific and, in several cases, more sensitive than the bioassay. In addition, the time of analysis is significantly shorter than the bioassay. We also found that SRM MSn was superior in the analysis of unknown incurred tissue than full spectrum MSn. We also obtained an MS/MS spectrum of DCCD that is significantly at variance with previously published fragmentation spectra. Published in 2003 by John Wiley & Sons, Ltd.
Detection of inorganic species by chemical reaction laser desorption ionization mass spectrometry
Authors: Matsumoto Kozo , Ajiro Hiroharu , Habaue Shigeki , Okamoto Yoshio
Published: March 2003

The oxidation numbers of metals in inorganic compounds were identified by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) by using their acetylacetonates, which are soluble in acetone. For the MALDI analysis of inorganic species insoluble in common solvents used for matrices, such as acetone, methanol, water, etc., a suspension method of sample preparation was developed. Turbid suspensions of inorganic species in the solvent were spotted on the sample holder with chelating reagents, as in the conventional sample preparation for MALDI‐MS. Chemical reaction between the inorganic species and the chelating reagents occurred in the plume after irradiation by laser light. Metal oxides were also analyzed by this method, and samples with different oxidation numbers gave different mass spectra. These results suggest that many other metal oxides with different oxidation numbers could be identified if suitable chelating reagents are chosen for sample preparation for MALDI‐MS. Copyright © 2003 John Wiley & Sons, Ltd.
Stable isotope dilution method for the determination of guanidinoacetic acid by gas chromatography/mass spectrometry
Authors: Fingerhut Ralph
Published: March 2003

For more than 30 years, guanidinoacetic acid (GAA), together with other guanidino compounds, has been proposed as an important marker for renal failure, in kidney transplantation, and for renal metabolism, especially for the metabolic activity of the renal proximal tubules. Since the discovery of the first patient with guanidinoacetic acid methyltransferase deficiency in 1994 by Stöckler et al. (Pediatr. Res. 1994; 36: 409), GAA has become of great interest for all laboratories involved in the diagnosis of metabolic diseases. In the literature there are several methods described for the determination of GAA, ranging from ion‐exchange chromatography with post‐column derivatisation, enzymatic methods, gas chromatography/mass spectrometry (GC/MS), to liquid chromatography/atmospheric pressure chemical ionisation mass spectrometry (LC/APCI‐MS). Here a stable isotope dilution method for quantitative and accurate determination of GAA in urine, plasma, and cerebrospinal fluid is described. GAA is converted to the bis(trifluoromethyl)pyrimidine di(tert‐butyldimethylsilyl) derivative by stepwise derivatisation with hexafluoroacetylacetone and N‐(tert‐butyldimethylsilyl)‐N‐methyltrifluoroacetamide (MTBSTFA). Analysis can be performed using a standard benchtop GC/MS system. For quantitative GAA determination with 1,2‐13C‐GAA as internal standard, selected ion monitoring is performed using m/z 460/462, with m/z 432/433 and 375/376 as qualifiers. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of class I phosphoinositide 3‐kinase autophosphorylation sites by mass spectrometry
Authors: Czupalla Cornelia , Nürnberg Bernd , Krause Eberhard
Published: March 2003

This article describes the identification of the autophosphorylation sites of the G protein‐sensitive class I phosphoinositide 3‐kinase isoforms β and γ by mass spectrometry. Since discrimination and suppression effects prevented the immediate detection and sequencing of phosphopeptides in complex mixtures, a strategy was applied that involved 32P‐radiolabeling of the phosphoproteins, cleavage of the phosphoproteins with several proteases and/or cyanogen bromide, separation of the resulting peptide mixtures by micro‐reversed‐phase liquid chromatography, and mass spectrometric analysis of fractions containing phosphopeptides. As a result the primary autophosphorylation sites of phosphoinositide 3‐kinase p110β and p110γ subunits could be unambiguously assigned to the C‐terminal Ser 1070 and Ser 1101, respectively. Copyright © 2003 John Wiley & Sons, Ltd.
Nitrogen isotopomer site preference of N2O produced by Nitrosomonas europaea and Methylococcus capsulatus Bath
Authors: Sutka R. L. , Ostrom N. E. , Ostrom P. H. , Gandhi H. , Breznak J. A.
Published: March 2003

The relative importance of individual microbial pathways in nitrous oxide (N2O) production is not well known. The intramolecular distribution of 15N in N2O provides a basis for distinguishing biological pathways. Concentrated cell suspensions of Methylococcus capsulatus Bath and Nitrosomonas europaea were used to investigate the site preference of N2O by microbial processes during nitrification. The average site preference of N2O formed during hydroxylamine oxidation by M. capsulatus Bath (5.5 ± 3.5‰) and N. europaea (−2.3 ± 1.9‰) and nitrite reduction by N. europaea (–8.3 ± 3.6‰) differed significantly (ANOVA, f(2,35) = 247.9, p = 0). These results demonstrate that the mechanisms for hydroxylamine oxidation are distinct in M. capsulatus Bath and N. europaea. The average δ18O‐N2O values of N2O formed during hydroxylamine oxidation for M. capsulatus Bath (53.1 ± 2.9‰) and N. europaea (−23.4 ± 7.2‰) and nitrite reduction by N. europaea (4.6 ± 1.4‰) were significantly different (ANOVA, f(2,35) = 279.98, p = 0). Although the nitrogen isotope value of the substrate, hydroxylamine, was similar in both cultures, the observed fractionation (Δ15N) associated with N2O production via hydroxylamine oxidation by M. capsulatus Bath and N. europaea (−2.3 and 26.0‰, respectively) provided evidence that differences in isotopic fractionation were associated with these two organisms. The site preferences in this study are the first measured values for isolated microbial processes. The differences in site preference are significant and indicate that isotopomers provide a basis for apportioning biological processes producing N2O. Copyright © 2003 John Wiley & Sons, Ltd.
Generation and reactions of substituted phenide anions in an electrospray triple quadrupole mass spectrometer
Authors: Bieńkowski Tomasz , Danikiewicz Witold
Published: March 2003

Substituted benzoic acid anions undergo decarboxylation in the medium‐pressure region of an electrospray ion source yielding in most cases the correspondingly substituted phenide anions in high yield. The location of the anionic center is specified by the position of the carboxylic group. The only exceptions are compounds with substituents containing acidic hydrogen atoms, like OH and NH2 groups. For such compounds, either an intra‐ or an intermolecular (mediated by the molecules of methanol or water) proton transfer from the more acidic position to the benzene ring is observed. The generated anions can be selected using the first quadrupole for studying their ion‐molecule chemistry in the second quadrupole of a triple quadrupole mass spectrometer. Their reactions with CO2, O2, CH3COCH3 and CCl4 may serve as typical examples. The general applicability of this method for the generation of phenide anions has been confirmed on three different mass spectrometers. Experiments performed using carboxylic acids other then benzoic acid and its derivatives show that this method is not limited to phenide anions and can be used for the generation of a much wider range of carbanions in the gas phase. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of α‐tocopherol in infant foods by liquid chromatography combined with atmospheric pressure chemical ionisation mass spectrometry
Authors: Kalman Andras , Mujahid Claudia , Mottier Pascal , Heudi Olivier
Published: March 2003

A novel, sensitive and specific method for the quantification of α‐tocopherol in two infant foods (milk and cereals) using liquid chromatography on‐line with positive atmospheric pressure chemical ionisation mass spectrometry detection (LC/APCI‐MS) has been developed. The samples were first saponified in order to eliminate fats and to transform tocopherol esters into free tocopherol, followed up by a liquid–liquid extraction of the analyte in petroleum benzine/diisopropyl ether (75:25, v/v) prior to injection onto the LC system. For the quantification, deuterium‐labelled tocopherol was used as internal standard and the samples were monitored in selected ion monitoring (SIM) mode. Calibration curves between 1–40 μg/mL of α‐tocopherol showed a good linear correlation (r2 = 0.99994), and the detection limit was determined to be 2.5 ng/mL. The within‐day and between‐day precision were determined for several dietetic infant formulae and certified reference samples, and found to be below 3.5%. The accuracy determined on a Nestlé reference sample (milk powder) was calculated to be 115.2 ± 1.2%, which confirms the robustness of the proposed method. This study shows that single quadrupole LC/MS can be applied for the quantification of vitamins in food and the method offers better sensitivity and selectivity than traditional method such as LC‐UV. This would simplify the preparation of the food samples and consequently enhance the vitamin analysis throughput in the food area. Copyright © 2003 John Wiley & Sons, Ltd.
Improved liquid chromatography/mass spectrometric analysis of low molecular weight carboxylic acids by ion exclusion separation with electrospray ionization
Authors: Gamoh Keiji , Saitoh Hiroki , Wada Hiroo
Published: March 2003

An improved, simple and sensitive analytical method for low molecular weight organic acids has been developed. A mixture of acetic, propionic, butyric, glycolic, lactic, 2‐hydroxybutyric, malonic, succinic, glutaric, tartaric and citric acids was separated on a semi‐rigid styrene‐divinylbenzene copolymer‐based H‐type cation‐exchange resin (ULTRON PS‐80H) based on an ion exclusion chromatographic (IEC) mechanism, with detection using electrospray ionization mass spectrometry (ESI‐MS). Formic or acetic acid was used as a mobile phase to separate the carboxylic acids within 15 min. For liquid chromatography/mass spectrometry (LC/MS), the ESI interface was used in both positive and negative ionization mode. ESI produced reasonable signals from positive ions, [M+NH4]+, of acetic, propionic and butyric acids and from negative ions, [MH]−, of glycolic, lactic, 2‐hydroxybutyric, malonic, succinic, glutaric, tartaric and citric acids. The effects of ionization parameters, source temperature, capillary voltage and cone voltage, on sensitivity and linearity were examined. Linear plots of peak area versus concentration were obtained over the range 0.1–20 ppm for MS detection. The detection limits of the target carboxylic acids calculated at signal‐to‐noise (S/N) ratio of 3 ranged from 9 to 59 ppb. The reproducibility of retention times and peak areas were 0.55–1.25 and 0.85–2.45%, respectively. Copyright © 2003 John Wiley & Sons, Ltd.
Atmospheric pressure chemical ionisation reversed‐phase liquid chromatography/ion trap mass spectrometry of intact bacteriohopanepolyols
Authors: Talbot Helen M. , Squier Angela H. , Keely Brendan J. , Farrimond Paul
Published: March 2003

Atmospheric pressure chemical ionisation liquid chromatography/multi‐stage ion trap mass spectrometry (APCI‐LC/MSn) has been applied to the study of intact bacteriohopanepolyols. Spectral characterisation of bacteriohopanepolyols of known structure present in bacterial extracts (Zymomonas mobilis and a fermenter containing methanotrophs including Methylococcus capsulatus) has revealed greater structural detail than previous liquid chromatography/mass spectrometry (LC/MS) methods and identified characteristic fragmentations indicative of numerous biohopanoid structures. Analysis of a Recent sedimentary extract from Lake Druzhby (Antarctica) has demonstrated the power of this technique to detect biohopanoids in complex samples including at least partial characterisation of previously unknown composite structures. Copyright © 2003 John Wiley & Sons, Ltd.
Tandem mass spectra of ammonium ion, metal ion and ligated metal ion adducts of acyclic sugar derivatives
Authors: Madhusudanan K. P. , Kumar B. , Pathak R. , Pant C. S. , Shaw A. K.
Published: March 2003

The tandem mass (MS/MS) spectra of ammonium ion, metal ion and ligated metal ion adducts of chain‐extended acyclic nitro‐containing deoxyglucose and deoxygalactose derivatives have been studied. The ammonium adducts fragment primarily by elimination of ammonia followed by acetic acid, thus not giving much structural information. In contrast, cationization of these compounds by metal ions and ligated metal ions gave structurally informative and useful fragment ions on MS/MS. The metal ions and ligated metal ions play an important role in controlling and directing fragmentation. Retro‐aldol fragmentation is facilitated by metal ions such as Li+, Na+, Ag+ and Cu+, whereas the adducts with higher alkali metal ions such as Rb+ and Cs+ fragment to give only the corresponding metal ions. The divalent metal ions such as Cu2+ and Ba2+ also induce retro‐aldol fragmentation. However, the charge is carried by the aldehyde fragment in the case of Cu2+ adducts, whereas the nitroalkane fragment carries the charge in the case of Ba2+ adducts. Ligated metal ions such as ZnCl+, CuCl+, InCl2+ and BaCl+ also behave similarly and induce retro‐aldol fragmentation in these acyclic sugars. Both the metal ion and ligated metal ion adducts can fragment by elimination of metal‐containing neutral molecules. Copyright © 2003 John Wiley & Sons, Ltd.
Learning environment, motivation, and achievement in high school science
Authors: Nolen Susan Bobbitt
Published: March 2003

In a study of the relationship between high school students' perceptions of their science learning environments and their motivation, learning strategies, and achievement, 377 students in 22 introductory science classrooms completed surveys in the fall and spring of their ninth‐grade year. Hierarchical linear regression was used to model the effects of variables at both the classroom and individual level simultaneously. High intraclass agreement (indicated by high parameter reliability) on all classroom environment measures indicated that students shared perceptions of the classroom learning environment. Controlling for other factors, shared perceptions that only the most able could succeed in science classrooms and that instruction was fast‐paced and focused on correct answers negatively predicted science achievement, as measured on a districtwide curriculum‐linked test. Shared perceptions that classrooms focused on understanding and independent thinking positively predicted students' self‐reported satisfaction with learning. Implications of these results for both teaching and research into classroom environments are discussed. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 347–368, 2003
High school students' ideas about theories and theory change after a biological inquiry unit
Authors: Sandoval William A. , Morrison Kathryn
Published: March 2003

Students' epistemological beliefs about scientific knowledge and practice are one important influence on their approach to learning. This article explores the effects that students' inquiry during a 4‐week technology‐supported unit on evolution and natural selection had on their beliefs about the nature of science. Before and after the study, 8 students were interviewed using the Nature of Science interview developed by Carey and colleagues. Overall, students held a view of science as a search for right answers about the world. Yet, the inconsistency of individuals' responses undermines the assumption that students have stable, coherent epistemological frameworks. Students' expressed ideas did not change over the course of the intervention, suggesting important differences between students' talk during inquiry and their abilities to talk epistemologically about science. Combined with previous work, our findings emphasize the crucial role of an explicit epistemic discourse in developing students' epistemological understanding. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 369–392, 2003
Intervention program to keep girls in the science pipeline: Outcome differences by ethnic status
Authors: Jayaratne Toby Epstein , Thomas Nancy G. , Trautmann Marcella
Published: March 2003

This study evaluated a 2‐week residential program aimed at enhancing the science interest and persistence of high‐achieving 8th‐grade girls. Questionnaires were administered to 38 program participants (14 of whom were of minority ethnicity) and 173 applicants who did not attend the program, at 3 time points: preprogram, 1 year postprogram, and 4 years postprogram. Outcomes, measured postprogram, included science self‐concept and interest, persistence and aspirations in science, science activities, science course‐taking in high school, and plans for a science college major. There was no main effect of program participation on any of the outcome measures, but a significant Participation × Ethnicity interaction effect occurred for all but one of the outcome variables. At Time 2, and especially Time 3, nonminority participants tended to have the most positive outcomes, whereas minority participants tended to have the most negative outcomes, compared with applicants. Post hoc analyses showed that although nonminority girls overall were more advantaged, this difference did not explain results. Several interpretations for these findings are discussed, the most likely that some global feature of the program, not any intervention component, interacted over time with the girls' postprogram experience. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 393–414, 2003
Cognitive factors affecting student understanding of geologic time
Authors: Dodick Jeff , Orion Nir
Published: March 2003

A critical element of the earth sciences is reconstructing geological structures and systems that have developed over time. A survey of the science education literature shows that there has been little attention given to this concept. In this study, we present a model, based on Montagnero's (1996) model of diachronic thinking, which describes how students reconstruct geological transformations over time. For geology, three schemes of diachronic thinking are relevant: 1. Transformation, which is a principle of change; in geology it is understood through actualistic thinking (the idea that present proceeses can be used to model the past). 2. Temporal organization, which defines the sequential order of a transformation; in geology it is based on the three‐dimensional relationship among strata. 3. Interstage linkage, which is the connections between successive stages of a transformation; in geology it is based on both actualism and causal reasoning. Three specialized instruments were designed to determine the factors which influence reconstructive thinking: (a) the GeoTAT which tests diachronic thinking skills, (b) the TST which tests the relationship between spatial thinking and temporal thinking, and (c) the SFT which tests the influence of dimensional factors on temporal awareness. Based on the model constructed in this study we define the critical factors influencing reconstructive thinking: (a) the transformation scheme which influences the other diachronic schemes, (b) knowledge of geological processes, and (c) extracognitive factors. Among the students tested, there was a significant difference between Grade 9–12 students and Grade 7–8 students in their ability to reconstruct geological phenomena using diachronic thinking. This suggests that somewhere between Grades 7 and 8 it is possible to start teaching some of the logical principles used in geology to reconstruct geological structures. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 415–442, 2003
The lung‐to‐head ratio and fetoscopic temporary tracheal occlusion: prediction of survival in severe left congenital diaphragmatic hernia
Authors: Keller R. L. , Glidden D. V. , Paek B. W. , Goldstein R. B. , Feldstein V. A. , Callen P. W. , Filly R. A. , Albanese C. T.
Published: March 2003

Objectives

To evaluate the reliability of sonographic lung‐to‐head ratio (LHR) measurement as a predictor of survival in fetuses with congenital diaphragmatic hernia (CDH) and to compare the probability of survival in those with temporary tracheal occlusion (TO) or standard care with respect to the LHR.

Methods

Fifty‐six fetuses with left CDH with liver herniated into the thorax at complete prenatal evaluation were included in logistic regression analyses of antenatal predictors of survival to hospital discharge. Sixteen subjects underwent TO and 40 received standard care.

Results

LHR was a significant predictor of survival, with probability of survival increasing with increasing LHR (odds ratio (OR) 8.5, P = 0.04). When subjects with anomalies were excluded, the LHR effect was similar after adjustment for TO (OR 7.1, P = 0.11). Linear spline models suggested a plateau in survival at an LHR of 1.0 and all models suggested increased odds of survival with TO. Minimum LHR measurements had a high degree of inter‐ and intraobserver agreement (intraclass correlation coefficients of 0.70 and 0.80, respectively).

Conclusions

Calculation of the LHR in fetuses with CDH is a reliable and powerful predictor of survival to hospital discharge, although improving odds of survival may plateau at an LHR of 1.0. TO may have an independent benefit on survival to hospital discharge. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
The role of fetal nuchal translucency and ductus venosus Doppler at 11–14 weeks of gestation in the detection of major congenital heart defects
Authors: Favre R. , Cherif Y. , Kohler M. , Kohler A. , Hunsinger M.‐C. , Bouffet N. , Tanghe M. , Cancellier M. , Nisand I.
Published: March 2003

Objective

To determine whether, in a selected high‐risk population, Doppler velocimetry of the ductus venosus can improve the predictive capacity of increased nuchal translucency in the detection of major congenital heart defects in chromosomally normal fetuses at 11–14 weeks of gestation.

Methods

Ductus venosus Doppler ultrasound blood velocity waveforms were obtained prospectively at 11–14 weeks of gestation in 1040 consecutive singleton pregnancies. Waveforms were classified either as normal in the presence of a positive A‐wave, or as abnormal if the A‐wave was absent or negative. All cases were screened for chromosomal defects by a combination of maternal age and fetal nuchal translucency thickness. In 484 cases karyotyping was performed. Those fetuses found to be chromosomally normal by prenatal cytogenetic analysis, and which had abnormally increased nuchal translucency and/or abnormal ductus venosus Doppler velocimetry, underwent fetal echocardiography at 14–16 weeks of gestation. Ultrasound examination was repeated at 22–24 weeks of gestation in all women. The sensitivity, specificity and positive and negative predictive values for the detection of major cardiac defects of increased nuchal translucency thickness alone, ductus venosus Doppler alone and increased nuchal translucency thickness in association with abnormal ductus venosus Doppler were determined.

Results

In 29 of 998 fetuses presumed to be chromosomally normal, reversed or absent flow during atrial contraction was associated with increased (> 95
th
centile for crown–rump length) nuchal translucency. Major cardiac defects were observed in 9 of these 29 fetuses. No other major cardiac abnormalities were found in chromosomally normal fetuses in spite of the presence of either increased nuchal translucency alone or abnormal ductus venosus velocimetry. A total of 25 cardiac malformations were observed in the population. Fifteen were associated with aneuploidy and 10 fetuses had a normal karyotype. Nine of the 10 had major cardiac anomalies and one had a ventricular septal defect. The nine cases with normal karyotype and major cardiac anomalies had both increased nuchal translucency and abnormal ductus venosus flow velocity waveforms.

Conclusion

In chromosomally normal fetuses with increased nuchal translucency, assessment of ductus venosus blood flow velocimetry could improve the predictive capacity for an underlying major cardiac defect. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal brain/liver volume ratio and umbilical volume flow parameters relative to normal and abnormal human development
Authors: Boito S. , Struijk P. C. , Ursem N. T. C. , Fedele L. , Wladimiroff J. W.
Published: March 2003

Objectives

To estimate fetal brain volume from head circumference and published postmortem data; to determine normal values for the fetal brain/liver volume ratio relative to gestational age; to establish the relationship between the brain/liver volume ratio and fetal circulatory parameters during normal and restricted (SGA) fetal growth.

Patients and Method

This was a cross‐sectional study involving a total of 47 uncomplicated pregnancies appropriate‐for‐gestational age (AGA) and 23 pregnancies resulting in the delivery of a SGA fetus. At enrollment gestational age ranged between 20 and 36 weeks in both groups. Umbilical venous cross‐sectional area and time‐averaged velocity for calculation of volume flow as well as velocity waveforms from the umbilical artery, middle cerebral artery and ductus venosus, were recorded. Fetal liver volume measurements were obtained using three‐dimensional ultrasound. Fetal brain volume was estimated from fetal head volume following comparison with published postmortem data on fetal brain weight.

Results

A significant correlation was observed between prenatally estimated fetal head volume and postmortem fetal brain volume. Fetal brain volume was approximately half that of fetal head volume. The normal fetal brain/liver volume ratio demonstrated a significant reduction with gestational age (R = −0.54; P < 0.001). The normal mean ± standard
deviation (SD) fetal brain/liver volume ratio (3.4 ± 0.7) was significantly different (P < 0.001) from the mean fetal brain/liver volume ratio in the SGA group (n = 23) (5.9 ± 1.9). A significant difference existed for mean umbilical venous volume flow between AGA (104.7 ± 26.9 mL/min/kg) and SGA (59.6 ± 22.7 mL/min/kg) fetuses. In the SGA fetus, there was a significant inverse relationship (P < 0.001) between fetal weight‐related umbilical venous volume flow and fetal brain/liver volume ratio. In a subset of 16 SGA and 16 AGA fetuses matched for gestational age, a significant difference existed for umbilical artery pulsatility index (2.30 ± 1.52 vs. 0.99 ± 0.19), fetal middle cerebral artery pulsatility index (1.3 ± 0.4 vs. 2.1 ± 0.3) and late diastolic flow velocity in the fetal ductus venosus (6.9 ± 14.2 cm/s vs. 23.9 ± 8.8 cm/s), but not for peak systolic, early diastolic and time‐averaged velocity in the ductus venosus.

Conclusion

Sonographic estimates of fetal brain volume can be obtained. The fetal brain/liver volume ratio is a predictor of fetal outcome in the growth‐restricted fetus. An inverse relationship exists in SGA fetuses between brain/liver volume ratio and fetal weight‐related umbilical venous blood flow. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
First‐trimester diagnosis and management of pregnancies implanted into the lower uterine segment Cesarean section scar
Authors: Jurkovic D. , Hillaby K. , Woelfer B. , Lawrence A. , Salim R. , Elson C. J.
Published: March 2003

Objective

To describe first‐trimester ultrasound diagnosis and management of pregnancies implanted into uterine Cesarean section scars.

Methods

All women referred for an ultrasound scan because of suspected early pregnancy complications were screened for pregnancies implanted into a previous Cesarean section scar. The management of Cesarean section scar pregnancies included transvaginal surgical evacuation, medical treatment with local injection of 25 mg methotrexate into the exocelomic cavity and expectant management.

Results

Eighteen Cesarean section scar pregnancies were diagnosed in a 4‐year period. The prevalence in the local population was 1 : 1800 pregnancies. Surgical treatment was used in eight women and it was successful in all cases. The respective success rates of medical treatment and expectant management were 5/7 (71%) and 1/3 (33%). Five women (28%) required blood transfusion and one woman (6%) had a hysterectomy.

Conclusions

Cesarean section scar pregnancies are more common than previously thought. When the diagnosis is made in the first trimester the prognosis is good and the risk of hysterectomy is relatively low. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Contraction stress test versus ductus venosus Doppler evaluation for the prediction of adverse perinatal outcome in growth‐restricted fetuses with non‐reassuring non‐stress test
Authors: Figueras F. , Martínez J. M. , Puerto B. , Coll O. , Cararach V. , Vanrell J. A.
Published: March 2003

Objective

To compare Doppler evaluation of the ductus venosus and contraction stress test (CST) in the prediction of adverse perinatal outcome in growth‐restricted fetuses with evidence of hemodynamic redistribution and a non‐reactive non‐stress test (NST).

Methods

Data were collected from all singleton pregnancies seen in our Fetal Surveillance Unit who underwent antenatal monitoring for fetal growth restriction, non‐reactive NST and arterial redistribution beyond 26 weeks of pregnancy. Patients were divided into four groups based on their CST and ductus venosus waveform results. Perinatal outcome was evaluated by means of four variables: the need for admission to the neonatal intensive care unit (NICU), need for neonatal intubation, an umbilical artery pH < 7.10 and significant neonatal morbidity. Outcome was compared among fetuses delivered within 3 days of their antenatal test. Logistic regression analysis was used to analyze the relation between predictive and outcome variables.

Results

Sixty‐eight women met the inclusion criteria for the study. The positive predictive value of the CST was 45% for admission to the NICU, 13% for significant neonatal morbidity, 26% for need of neonatal intubation and 29% for umbilical artery pH < 7.10. The positive predictive values of abnormal ductus venosus waveform (ADVW) were 81.5%, 26%, 48% and 55%. Groups with ADVW showed significantly poorer neonatal outcome. No significant differences were observed when CST results were compared. Logistic regression analysis showed that both gestational age at delivery and ADVW significantly predict the occurrence of adverse perinatal outcome.

Conclusion

In growth‐restricted fetuses with hemodynamic redistribution and a non‐reassuring NST, Doppler assessment of the ductus venosus correlates with adverse perinatal outcome. In this clinical situation there is no benefit of CST in terms of prediction. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
The interobserver reliability and validity of volume calculation from three‐dimensional ultrasound datasets in the in vitro setting
Authors: Raine‐Fenning N. J. , Clewes J. S. , Kendall N. R. , Bunkheila A. K. , Campbell B. K. , Johnson I. R.
Published: March 2003

Objectives

The primary aim of this validation study was to determine the interobserver reliability and validity of measurements of phantom objects of known volume using conventional and rotational techniques of volume calculation according to measurement technique.

Methods

Two observers each acquired a single three‐dimensional ultrasound dataset of three water‐filled objects of different size and shape. The same two observers measured all six datasets using both the conventional technique and the newer rotational technique (Virtual Organ Computer‐aided AnaLysis, VOCAL™) of volume calculation. Reliability was assessed by calculating intraclass correlation coefficients (ICC) and validity by examining the percentage difference from the ‘true’ volume, as determined by a water displacement technique, by the limits of agreement method.

Results

All of the techniques were highly reliable (ICC: 0.9962–0.9997) and valid to within 4% of the ‘true’ volumes. There were no significant differences in reliability according to measurement plane or between observers. Measurements made with the 6° rotation step were significantly more reliable than those made by all other techniques with the exception of the 9° rotation step (P < 0.05) and significantly more valid than those made with the 30° rotation step or conventional technique (P < 0.05).

Conclusions

Volume calculation in the in vitro setting is both reliable and valid but is dependent upon the technique applied, with rotational measurements of volume proving superior to conventional techniques. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Intraobserver and interobserver variability of ovarian volume, gray‐scale and color flow indices obtained using transvaginal three‐dimensional power Doppler ultrasonography
Authors: Järvelä I. Y. , Sladkevicius P. , Tekay A. H. , Campbell S. , Nargund G.
Published: March 2003

Objective

To assess intraobserver and interobserver variability in ovarian volume and gray‐scale and color flow index measurements using transvaginal, three‐dimensional, power Doppler ultrasonography.

Methods

Eleven women (22 ovaries) were examined on day 8 of controlled ovarian hyperstimulation therapy, which was part of their in vitro fertilization treatment protocol. The patients were examined twice by the first observer and once by the second observer. The acquired volume datasets were analyzed using the VOCAL™ imaging program, enabling the assessment of ovarian volume, vascularization index (VI), flow index (FI), vascularization flow index (VFI) and mean grayness (MG). For these parameters the intraclass (intra‐CC) and interclass (inter‐CC) correlation coefficients, within‐observer and between‐observers repeatability coefficient (r) and limits of agreement were calculated.

Results

Both intraobserver and interobserver repeatability of ovarian volume measurements were considered very good with an intra‐CC value of 1.00 and inter‐CC value of 0.99, respectively. Also VI, FI, VFI and MG measurements were repeatable by a single observer, the intra‐CC ranging from 0.82 to 0.91. The interobserver reproducibility was also good for VI, VFI and MG measurements (inter‐CC values 0.73, 0.70 and 0.81, respectively), but for FI measurements the reproducibility was poor (inter‐CC = 0.29, r = 7.87).

Conclusions

In general, the intraobserver reproducibility was better than interobserver reproducibility for all parameters. The volume assessments were reproducible both by one observer and by two separate observers. The intraobserver and interobserver variabilities were acceptable for VI, VFI and MG, whereas for FI the interobserver reproducibility was poor. Our results suggest that measurement of gray‐scale and color Doppler flow indices is reproducible thus allowing them to be used in clinical practice and research. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Pulmonary stenosis and atresia with intact ventricular septum during prenatal life
Authors: Todros T. , Paladini D. , Chiappa E. , Russo M. G. , Gaglioti P. , Pacileo G. , Cau M. A. , Martinelli P.
Published: March 2003

Aim

To identify fetal echocardiographic characteristics predictive of perinatal outcome in cases with a prenatal diagnosis of pulmonary stenosis or pulmonary atresia.

Patients and methods

We retrospectively reviewed the records and the videotapes of all the cases of pulmonary stenosis and pulmonary atresia diagnosed at our institutions between 1990 and 1999. The following measurements were obtained: diameters of right and left atria and ventricles and ventricular wall thickness; main pulmonary artery and aortic root diameter; direction of flow through the atrioventricular, aortic and pulmonary valves and through the ductus arteriosus. Perinatal outcome and follow‐up of the survivors were available in each case.

Results

There were 21 cases of pulmonary atresia. Eleven were diagnosed before 24 weeks and nine of them (82%) underwent termination of pregnancy. The survival rate was 50% among the 12 fetuses born at term. None of the fetuses that survived had a large right ventricle, while this was a finding in 50% of those that died. Among the fetuses that died, 83% had a hypertrophic right ventricular wall compared to 33% of the survivors. There were 12 cases of pulmonary stenosis. Three cases were diagnosed before 24 weeks but none underwent termination of pregnancy. All the fetuses with pulmonary stenosis were born at term and four died in the perinatal period. The survival rate was thus 66.6% (8/12). Three (75%) of the fetuses that died had reversed flow in the ductus arteriosus compared with one of the fetuses that survived.

Conclusion

Our data suggest that a grossly enlarged right ventricle and/or a hypertrophied right ventricular wall in cases of pulmonary atresia and reversed flow in the arterial duct in cases of pulmonary stenosis are likely indicators of a poor prognosis. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal supraventricular tachycardia diagnosed and treatedat 13 weeks of gestation: a case report
Authors: Porat S. , Anteby E. Y. , Hamani Y. , Yagel S.
Published: March 2003

Supraventricular tachycardia (SVT) is the most commonly encountered clinically significant tachycardia in the fetus. When SVT is sustained, congestive heart failure and fetal hydrops may ensue, due to both systolic and diastolic dysfunction. Sonographic diagnosis is usually incidental during the second or third trimester. Treatment goals are cardioversion to sinus rhythm and reversal of cardiac dysfunction. We describe a case of fetal SVT diagnosed at 13 weeks of gestation. Treatment with digoxin and flecainide was successful; the heart rate returned to sinus rhythm within one day, and fetal hydrops resolved within 8 days of treatment. We suspect that as more first‐trimester examinations are performed, more cases with SVT will be diagnosed. We discuss the treatment protocol, and suggest that co‐administration of two drugs that act synergistically may be more efficient than monotherapy, which is currently used as the first line of treatment. In addition, we discuss the potentially deleterious effect of heart failure encountered at an early developmental stage on the central nervous system. More data need to be collected in order to substantiate a clear recommendation regarding optimal management. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Skewed fetal gender distribution in prolonged pregnancy: a fallacy with consequences
Authors: Kitlinski Laczna M. , Källén K. , Mars̆ál K. , Olofsson P.
Published: March 2003

Objective

Skewed gender distribution and falsely assigned gestational age lead to unnecessary or late obstetric intervention in prolonged pregnancy. The aim of this study was to examine the consequences of a fetal gender‐dependent systematic 1.5‐day dating error at ultrasound fetometry.

Material and methods

A total of 82 484 singleton deliveries ≥37 weeks at 11 hospitals in southern Sweden from 1995 to 2000 were included. Frequencies of labor induction and Apgar scores <7 at 5 min were compared with regard to fetal gender, both before and after correction of gestational age by adding 0.75 days to female‐fetus pregnancies and subtracting 0.75 days from male‐fetus pregnancies.

Results

The uncorrected odds ratio for having a male baby at ≥42 weeks was 1.41 (95% confidence interval, 1.33–1.49). After adjusting gestational age by ±0.75 days, the odds ratio reduced to 0.90 (95% confidence interval, 0.84–0.95). The risk for labor induction was significantly above unity in male‐fetus pregnancies delivered after 41 weeks when gestational age was corrected for fetal gender, while the risk for female fetuses having a low Apgar score was not significantly increased compared to male fetuses (P = 0.087).

Conclusion

Skewed gender distribution in prolonged pregnancy results in a higher rate of labor induction in pregnancies with male fetuses at ≥41 weeks, and the risk for newborn females having a low Apgar score in prolonged pregnancy is not significantly increased compared to boys. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Single and multiple umbilical cord cysts in early gestation: two different entities
Authors: Ghezzi F. , Raio L. , Di Naro E. , Franchi M. , Cromi A. , Dürig P.
Published: March 2003

Objective

To investigate the prevalence of single and multiple umbilical cord cysts in the first trimester and to assess whether there is a difference in the pregnancy outcome between them.

Methods

A targeted sonographic morphological and morphometric evaluation of the umbilical cord was performed in consecutive patients between 7 and 14 weeks of gestation. Crown–rump length and umbilical cord diameter were measured in all cases. Nuchal translucency thickness was measured between 11 and 14 weeks' gestation. In pregnancies at very early gestational ages (7–10 weeks) an additional scan was performed between 11 and 14 weeks.

Results

A total of 1159 patients was screened. The prevalence of umbilical cord cysts was 2.1% (24/1159). The cysts were single and multiple in 18 and six cases, respectively. The median (range) largest umbilical cord cyst diameter was no different between multiple and single umbilical cord cysts (3.8 (2.1–18) mm vs. 3.05 (2.0–7.8) mm; P = 0.386). All women with a single umbilical cord cyst delivered an infant without structural abnormalities and without features suggestive of chromosomal abnormalities. Among the women with multiple umbilical cord cysts, four had a missed miscarriage and one had a fetus with obstructive uropathy.

Conclusion

Single and multiple umbilical cord cysts in the first trimester of gestation represent two different entities. While single cysts in the first trimester are associated with a favorable pregnancy outcome, the presence of multiple umbilical cord cysts is associated with an increased risk of miscarriage and aneuploidy. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.