bluuebunny/crossref_metadata_2025 huggingface dataset:
Reactive micelles: nitroso group transfer from N‐methyl‐N‐nitroso‐p‐toluenesulfonamide to amphiphilic amines
Authors: García‐Río L. , Hervés P. , Leis J. R. , Mejuto J. C. , Rodríguez‐Dafonte P.
Published: October 2004

The reactivity of N‐methyl‐N‐nitroso‐p‐toluene sulfonamide (MNTS) towards n‐alkylamines in water and in micellar aggregates was studied. Kinetic constants in both media were obtained. The pseudophase micellar model allows a satisfactory prediction of the experimental behaviour in all cases. The value obtained for the micellar pseudophase rate constant, k, is lower than that in bulk water. The increase in the observed rate constant, ko, with n‐alkylamine concentration is due to an increase in the local concentration of reactants in the micellar surface. The differences between kw and k values is due to the polarity of micellar pseudophase being lower than that in bulk water. Copyright © 2004 John Wiley & Sons, Ltd.
Theoretical study of protonated xylenes: ethene elimination and H,C‐scrambling reactions
Authors: Arstad Bjørnar , Kolboe Stein , Swang Ole
Published: October 2004

Quantum chemical calculations have been carried out to investigate various unimolecular rearrangements that can take place in protonated gas‐phase xylenes. Hydrogen and methyl group ring migrations were investigated. The barriers for hydrogen migrations are lower than the barriers for methyl group migrations. Mechanisms for ring expansion to seven‐membered rings, and for contraction to five‐membered rings were studied. Both of these mechanisms can eventually lead to ethene elimination. The most favourable ring expansion step goes through a 1,3‐hydrogen shift from a methyl group onto the arenium ring, forming a protonated methylcycloheptatriene. Interconversions between various ring‐expanded forms have been investigated. Re‐contraction can lead to an ethylbenzenium ion that could subsequently split off ethene. Alternatively, the xylenium ion can contract to a five‐membered ring. The immediate product is a bicyclic ion (bicyclo[3.1.0]hexane skeleton) that can rearrange further to give an ethylbenzenium ion, or the five‐ring system can split off ethene, and be converted into a cyclopentadienyl ion that can isomerize into a benzenium ion. Stable structures and transition states are calculated both at the B3LYP/cc‐pVTZ//B3LYP/6‐311G(d,p) and at the MP2/cc‐pVTZ//MP2/6‐31G(d) levels. The energies needed for ring expansion or ring contraction are not very different, and the calculations suggest that both reaction paths are possible, but the energy needed for actually splitting off an ethene molecule is lower along the expansion path. Copyright © 2004 John Wiley & Sons, Ltd.
A priori calculation of molecular properties to chemical accuracy
Authors: Helgaker Trygve , Ruden Torgeir A. , Jørgensen Poul , Olsen Jeppe , Klopper Wim
Published: October 2004

Quantum chemical methods for the calculation of molecular properties to chemical accuracy are reviewed. We begin by reviewing wave‐function based electronic structure theory, with emphasis on coupled‐cluster theory and the description of electron correlation in terms of virtual excitations from occupied to virtual molecular orbitals. Next, we discuss the expansion of molecular orbitals in atomic orbitals and the design of one‐electron basis sets for correlated calculations at the coupled‐cluster level of theory. In particular, we discuss the convergence of the electronic energy in the principal expansion as realized in the correlation‐consistent basis sets. Following this theoretical introduction, we consider the accurate calculation of atomization energies, reaction enthalpies, dipole moments and spectroscopic constants such as bond distances and harmonic and anharmonic force constants. For each property, we identify what levels of theory in terms of basis set (the one‐electron description) and virtual excitation level (the N‐electron description) are needed for agreement with experiment to chemical accuracy, that is, about 1 kcal mol−1 (1 kcal = 4.184 kJ) for atomization energies and reaction enthalpies, about 0.1 pm for bond distances and about 1 cm−1 for vibrational frequencies. In each case, we consider in detail the direction and magnitude of the changes in the calculated properties with improvements in the one‐ and N‐electron descriptions of the electronic system, paying particular attention to the cancellation of errors arising from the simultaneous truncations of the coupled‐cluster expansion and the one‐electron basis set. We emphasize that agreement with experiment, even with chemical accuracy, for a few selected properties is by itself no guarantee of quality and should never be taken as indicative of an accurate description of the electronic system. To ensure such a description, the errors arising from the truncations of the one‐ and N‐electron expansions must be controlled by carrying out sequences of calculations, where the different levels of theory are systematically varied and where convergence is carefully monitored. Copyright © 2004 John Wiley & Sons, Ltd.
Catalytic dehydrogenation of ethane over mononuclear Cr(III) surface sites on silica. part I. C—H activation by σ‐bond metathesis
Authors: Lillehaug Sindre , Børve Knut J. , Sierka Marek , Sauer Joachim
Published: October 2004

Mononuclear Cr(III)–silica models have been studied by quantum chemical methods with respect to catalytic activity toward dehydrogenation of ethane. Both cluster and slab models have been developed and used to explore the conceptual model of mononuclear Cr(III) with three covalent ligands that coordinate through oxygen. The study focuses on a reaction mechanism consisting of three main reaction steps: (1) C—H activation of ethane according to σ‐bond metathesis and accompanied by the formation of O—H and Cr—C bonds, (2) β‐H transfer to chromium with subsequent loss of ethene and (3) regeneration of the chromium site under evolution of H2. An alternative mechanism is also explored, in which C—H activation takes place at a reactive hydridochromium complex. Stationary points pertaining to these reactions have been optimized, and free energy calculations are used to identify the rate‐determining steps. The influence of the local structure of the chromium surface sites is explored by means of a number of idealized surface models and electronic energy profiles for the reactions. Copyright © 2004 John Wiley & Sons, Ltd.
Additional evidence of possible structural effect of diol units in preformed oligoesters on solution copolycondensation with x,y‐dihydroxytoluenes and their isomers promoted by tosyl chloride/dimethylformamide/pyridine
Authors: Higashi Fukuji , Tsubonouchi Shingo
Published: October 2004

A two‐stage copolycondensation of a mixture of equal parts of isophthalic acid and terephthalic acid was conducted using a tosyl chloride/dimethylformamide/pyridine condensing agent. In the initial stage x,y‐dihydroxytoluenes (x,y‐DHTs) or 2,4‐dihydroxyethylbenzene (2,4‐DHEB) was used and in the next stage isomeric DHTs or the DHEB was used. The results were examined in terms of how the reaction of the resulting oligomers with the next monomers proceeded, which was evaluated from distributions of the next monomers in the resultant copolymers as determined by 1H NMR. A structurally selective reaction was observed. The preformed oligomers from symmetrically substituted 3,5‐DHT reacted randomly with similarly substituted 2,6‐DHT or asymmetric 2,4‐DHEB, but those from 2,4‐DHEB reacted selectively with both of 3,5‐ and 2,6‐DHT. In the reactions of the oligomers from 2,6‐DHT, they reacted randomly with 2,6‐DHT but selectively with 2,4‐DHEB. Such selective reactions were also observed in the reaction of p‐isomeric 2,5‐DHT with the oligomers prepared from 3,5‐ or 2,6‐DHT. When the monomers were copolymerized simultaneously instead of stepwise, they distributed randomly in the resultant copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5687–5694, 2004
Intramolecular energy transferable (2,2‐diphenylvinyl)phenyl substituted poly(p‐phenylenevinylene) derivative with efficient photoluminescence and electroluminescence
Authors: Shin Dong‐Cheol , Kim Yun‐Hi , You Hong , Jin Jae Gyu , Kwon Soon‐Ki
Published: October 2004

A poly(p‐phenylenevinylene) (PPV) derivative containing a bulky (2,2‐diphenylvinyl)phenyl group in the side chain, EHDVP‐PPV, was synthesized by Gilch route. The reduced tolane‐bisbenzyl (TBB) defects, as well as the structure of the polymer, was confirmed by various spectroscopic methods. The intramolecular energy transfer from the (2,2‐diphenylvinyl)phenyl side group to the PPV backbone was studied by UV‐vis and photoluminescence (PL) of the obtained polymer and model compound. The polymer film showed maximum absorption and emission peaks at 454 and 546 nm, respectively, and high PL efficiency of 57%. A yellow electroluminescence (λmax = 548 nm) was obtained with intensities of 6479 cd/m2 when the light‐emitting diodes of ITO/PEDOT/EHDVP‐PPV/LiF/Al were fabricated. The maximum power efficiency of the devices was 0.729 lm/W with a turn‐on voltage of 3.6 V. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5636–5646, 2004
Atom transfer radical polymerization of ionic liquid 2‐(1‐butylimidazolium‐3‐yl)ethyl methacrylate tetrafluoroborate
Authors: Ding Shijie , Tang Huadong , Radosz Maciej , Shen Youqing
Published: October 2004

Polymeric forms of ionic liquids may have many potential applications because of their high thermal stability and ionic nature. They are generally synthesized by conventional free‐radical polymerization. Here we report a living/controlled free‐radical polymerization of an ionic liquid monomer, 2‐(1‐butylimidazolium‐3‐yl)ethyl methacrylate tetrafluoroborate (BIMT), via atom transfer radical polymerization. Copper bromide/bromide based initiator systems polymerized BIMT very quickly with little control because of fast activation but slow deactivation. With copper chloride as the catalyst and trichloroacetate, CCl4, or ethyl α‐chlorophenylacetate as the initiator, BIMT was polymerized at 60 °C in acetonitrile with first‐order kinetics with respect to the monomer concentration. The molecular weight was linearly dependent on the conversion. The monomer concentration strongly affected the polymerization: a low monomer concentration caused the polymerization to be incomplete, probably because of catalyst disproportionation in polar solvents. The addition of a small amount of pyridine suppressed such disproportionation, but a further increase in the amount of pyridine greatly slowed the polymerization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5794–5801, 2004
Preparing a polystyrene‐functionalized multiple‐walled carbon nanotubes via covalently linking acyl chloride functionalities with living polystyryllithium
Authors: Huang Hsuan‐Ming , Liu I‐Chun , Chang Ching‐Yu , Tsai Hung‐Chieh , Hsu Chuan‐Hsiao , Tsiang Raymond Chien‐Chao
Published: October 2004

A new method was developed for preparing polystyrene‐functionalized multiple‐walled carbon nanotubes (MWNTs) through the termination of anionically synthesized living polystyryllithium with the acyl chloride functionalities on the MWNTs. The acyl chloride functionalities on the MWNTs were in turn obtained by the formation of carboxyls via chemical oxidation and their conversion into acyl chlorides. The polystyrene‐functionalized MWNTs had good dispersion in common organic solvents, and this indicated good compatibility for the preparation of styrenic nanocomposite materials. The synthesis results and characterization data for the functionalized MWNTs, collected via Fourier transform infrared, thermogravimetric analysis, solid‐state NMR, and electron microscopy, are presented and discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5802–5810, 2004
MSDsite: A database search and retrieval system for the analysis and viewing of bound ligands and active sites
Authors: Golovin Adel , Dimitropoulos Dimitris , Oldfield Tom , Rachedi Abdelkrim , Henrick Kim
Published: October 2004

The three‐dimensional environments of ligand binding sites have been derived from the parsing and loading of the PDB entries into a relational database. For each bound molecule the biological assembly of the quaternary structure has been used to determine all contact residues and a fast interactive search and retrieval system has been developed. Prosite pattern and short sequence search options are available together with a novel graphical query generator for inter‐residue contacts. The database and its query interface are accessible from the Internet through a web server located at: http://www.ebi.ac.uk/msd‐srv/msdsite. Proteins 2005. © 2004 Wiley‐Liss, Inc.
All‐atom folding of the three‐helix HIV accessory protein with an adaptive parallel tempering method
Authors: Schug A. , Herges T. , Wenzel W.
Published: October 2004

All‐atom protein structure prediction from the amino acid sequence alone remains an important goal of biophysical chemistry. Recent progress in force field development and validation suggests that the PFF01 free‐energy force field correctly predicts the native conformation of various helical proteins as the global optimum of its free‐energy surface. Reproducible protein structure prediction requires the availability of efficient optimization methods to locate the global minima of such complex potentials. Here we investigate an adapted version of the parallel tempering method as an efficient parallel stochastic optimization method for protein structure prediction. Using this approach we report the reproducible all‐atom folding of the three‐helix 40 amino acid HIV accessory protein from random conformations to within 2.4 Å backbone RMS deviation from the experimental structure with modest computational resources. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Effects of mutations in tyrosine hydroxylase associated with progressive dystonia on the activity and stability of the protein
Authors: Royo Montserrat , Daubner S. Colette , Fitzpatrick Paul F.
Published: October 2004

Tyrosine hydroxylase (TyrH) catalyzes the conversion of tyrosine to dihydroxyphenylalanine (DOPA), the rate‐limiting step in the biosynthesis of dopamine. Four mutations in the TyrH gene have recently been described in cases of autosomal recessive DOPA‐responsive dystonia (Swaans et al., Ann Hum Genet 2000;64:25–31). All four are predicted to result in changes in single amino acid residues in the catalytic domain of the protein: T245P, T283M, R306H, and T463M. To determine the effects of these mutations on the molecular properties of the enzyme, mutant proteins containing the individual single amino acid changes have been expressed in bacteria and purified. Only the T283M mutation results in a decrease in the enzyme kcat value, while the T245P enzyme has a slightly higher value than the wild‐type enzyme. The only case in which a Km value for either tyrosine or tetrahydrobiopterin is perturbed is the T245P enzyme, for which the Km value for tyrosine has increased about 50%. In contrast to the minor effects of the mutations on enzyme activity, the stability is decreased significantly by the mutations. The R306H and T283M enzymes are the least stable, losing activity 30‐ and 50‐fold more rapidly than the wild‐type enzyme. The apparent Tm value for unfolding was decreased by 3.9, 8.2, and 7.2° for the T245P, R306H, and T463M enzymes, while the T283M enzyme was too unstable for measurement of a Tm value. The results establish that the physiological effects of the mutations are primarily due to the decreased stability of the mutant proteins rather than decreases in their intrinsic activities. Proteins 2005. © 2004 Wiley‐Liss, Inc.
The anti‐platelet approach targeting the fibrinogen ligand of the GPIIb/IIIa receptor
Authors: Tsikaris Vassilios
Published: October 2004

Activation of the platelet surface receptor GPIIb/IIIa is the final pathway of platelet aggregation, regardless of the initiating stimulus. RGD analogues, peptidomimetics and monoclonal antibodies to GPIIb/IIIa have been developed targeting the blockage of the receptor and inhibition of the fibrinogen binding. However, the intrinsic activating effect of GPIIb/IIIa blockers is widely discussed as one potential contributing factor for the disappointing outcome of trials with GPIIb/IIIa inhibitors. An alternative method for thrombus prevention could be the use of specific fibrinogen blockers since they will act at the final step of the platelet aggregation and are expected to leave the receptor unaffected. To achieve this target the design of the fibrinogen ligands could be based on (i) sequences derived from GPIIb/IIIa ligand binding sites, and (ii) sequences complementary to RGD and/or to fibrinogen γ‐chain. The available information, which could be used as a starting point for developing potent fibrinogen ligands, is reviewed. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
BAM‐L002—a new type of certified reference material for length calibration and testing of lateral resolution in the nanometre range
Authors: Senoner M. , Wirth Th. , Unger W. , Österle W. , Kaiander I. , Sellin R. L. , Bimberg D.
Published: October 2004

A new type of test sample for the determination of lateral resolution in surface analysis is presented. The certified reference material BAM‐L002 ‘Nanoscale strip pattern for length calibration and testing of lateral resolution’ is an embedded cross‐section of epitaxially grown layers of AlxGa1−xAs and InxGa1−xAs on GaAs substrate. The surface of the sample provides a flat pattern with strip widths of 0.4–500 nm. The combination of gratings, isolated narrow strips and sharp edges of wide strips offers improved possibilities for the calibration of a length scale, the determination of lateral resolution and the optimization of instrument settings. The feasibility of the reference material for an analysis of lateral resolution is demonstrated for SIMS. Copyright © 2004 John Wiley & Sons, Ltd.
Conceptual system design evaluation: Rating and ranking versus compliance analysis
Authors: Smith Caroline , Verma Dinesh
Published: October 2004

The conceptual design phase is a critical part of the systems engineering approach, in terms of commitment of both time and money. Structure and discipline at this time are fundamental to the efficient and effective development of competitive products and systems. However, the extent and resolution of information available during this phase, in the form of parameter values and priorities, is typically characterized by imprecision and subjectivity. Such uncertainty can be represented by fuzzy variables and linguistic values. Discrimination between competing product concepts thus necessitates identification of a defuzzification technique to allow comparison of imprecise requirements with imprecise expected values for conceptual alternatives. Since fuzzy numbers do not exhibit complete order, many existing defuzzification techniques are based on the philosophy of rating and ranking fuzzy sets. This paper argues that a defuzzification technique based on the degree of compliance between required and anticipated parameter values is more suited to concept evaluation and selection. The advantage of such an approach is demonstrated and a fuzzy logic based framework for this purpose is proposed. Finally, techniques for accelerating such a compliance analysis are suggested. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 338–351, 2004
The fetal esophagus: anatomical and physiological ultrasonographic characterization using a high‐resolution linear transducer
Authors: Malinger G. , Levine A. , Rotmensch S.
Published: October 2004

Objective

To study the sonographic anatomy and physiology of the human fetal esophagus during the mid‐trimester of pregnancy using a high‐resolution linear transducer.

Methods

This was a prospective observational study of the fetal esophagus between 19 and 25 weeks' gestation. The study was performed in 60 consecutive fetuses, after a normal anatomy scan, using a 5–13‐MHz matrix array wide‐band transducer. During the examination the collapsed esophagus was first visualized, and followed by a 5‐min video recording in order to demonstrate luminal patency and peristaltic waves.

Results

Complete anatomical visualization of the esophagus was possible in 52 (86.7%) patients and at least partial visualization in 58 (96.7%) patients. Three different patterns of esophageal motility were observed: a simultaneous and short opening of the whole esophagus was found in 35 (58.3%) fetuses; a segmental, peristalsis‐like movement from the pharynx, through the mediastinum, and into the stomach was found in 18 (30%) fetuses; and in one fetus reflux‐like passage of solid contents from the stomach was observed. The mean time required for demonstration of esophageal patency was 96.1 (range, 10–300) s.

Conclusions

Demonstration of normal anatomy and physiological activity of the fetal esophagus is feasible using appropriate transducers. The most commonly observed pattern of esophageal motility in the mid‐trimester of pregnancy is the simultaneous relaxation of the upper and lower esophageal sphincters with concurrent opening of the esophageal lumen from the upper thorax to the stomach. Demonstration of a patent esophagus may be helpful in fetuses with suspected esophageal atresia. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Sonographic features of decidualized ovarian endometriosis suspicious for malignancy
Authors: Fruscella E. , Testa A. C. , Ferrandina G. , Manfredi R. , Zannoni G. F. , Ludovisi M. , Malaggese M. , Scambia G.
Published: October 2004

The discovery of an ovarian mass during pregnancy is often a difficult issue because of the risk related to surgical intervention during pregnancy. Moreover, ultrasound examination is often unable to provide a definitive diagnosis. A case of decidualized ovarian endometriosis is presented to highlight the challenges in this diagnosis. We report the transvaginal ultrasound findings, including color Doppler examination, magnetic resonance characteristics and tumor marker longitudinal evaluation during the first trimester of pregnancy, as well as the final histological characteristics of the lesion. Decidualization is a rare occurrence in ovarian endometriosis and must be differentiated from malignant transformation. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Middle cerebral artery Doppler indices at different sites: prediction of umbilical cord gases in prolonged pregnancies
Authors: Figueras F. , Lanna M. , Palacio M. , Zamora L. , Puerto B. , Coll O. , Cararach V. , Vanrell J. A.
Published: October 2004

Objectives

To assess the value of middle cerebral artery Doppler indices obtained from different sampling sites in predicting umbilical cord gases at delivery in prolonged pregnancies.

Methods

This was a prospective study of consecutive pregnant women referred for prolonged‐pregnancy surveillance. The predictive value of distal and proximal middle cerebral artery Doppler indices for cord blood gases was evaluated in women who delivered within 48 h of their last antenatal test using stepwise multiple regression.

Results

There was a significant linear correlation between proximal and distal middle cerebral artery pulsatility indices (R = 0.777; P < 0.0001), the mean values being 1.49 (SD, 0.45) and 1.56 (SD, 0.47), respectively. There was also a linear correlation between proximal and distal cerebroplacental ratios (R = 0.68; P < 0.0001), the mean values being 1.85 (SD, 1.96) and 1.92 (SD, 1.89), respectively. The stepwise multiple regression analysis for umbilical artery pH showed that once the distal middle cerebral artery pulsatility index was introduced into the model, the addition of any variable did not result in a significant improvement of the predictive capacity. The model showed a coefficient of determination (R2) of 0.079. There was a significant correlation between umbilical artery pO2 and both proximal middle cerebral artery pulsatility index (positive) and the occurrence of elective Cesarean section (negative). This model accounted for 21% of the variance (R2 = 0.21). No other variables added any significant prediction for pO2.

Conclusions

In post‐term pregnancies the proximal middle cerebral artery pulsatility index significantly predicts umbilical artery pO2 at delivery but does not predict pH. There is a weak association between distal middle cerebral artery pulsatility index and pH but, as this only explains 8% of the variance, it is of little clinical value. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Assessment of fetal cerebral arterial and venous blood flow before and after vaginal delivery or Cesarean section
Authors: Baytur Y. B. , Tarhan S. , Uyar Y. , Ozcakir H. T. , Lacin S. , Coban B. , Inceboz U. , Caglar H.
Published: October 2004

Objectives

To compare perinatal intracranial arterial and venous blood velocity changes between healthy term neonates delivered vaginally or by Cesarean section and to correlate these changes with cord blood gases and pH values at birth.

Methods

The study involved 43 healthy term neonates who were delivered vaginally (n = 20) or by Cesarean section (n = 23). All fetuses/neonates were examined by Doppler ultrasound to obtain middle cerebral artery (MCA) and cerebral transverse sinus (Tsin) Doppler waveforms on three occasions (before delivery, and 1 h and 24 h after birth). Pulsatility index (PI) and peak systolic velocity (PSV) for MCA and Tsin were measured and compared between neonates who were delivered vaginally or by Cesarean section. Umbilical cord blood samples were analyzed for umbilical artery and vein pH, pO2 and pCO2 and values were correlated with MCA and Tsin Doppler indices.

Results

MCA‐PI increased and MCA‐PSV decreased at 1 h after birth, and Doppler measurements returned to predelivery values at 24 h after birth. Tsin Doppler measurements remained unchanged at 1 h and 24 h when compared to predelivery values in both the Cesarean and vaginal delivery groups. There was a negative correlation between Tsin‐PI before birth and umbilical venous pH. There was a positive correlation between Tsin‐PSV at 1 h after birth and umbilical vein pCO2.

Conclusions

Cerebral arterial blood velocity decreases immediately after birth and increases within 24 h, probably as part of neonatal adaptation. Cerebral venous blood velocity remains constant during the perinatal period and is likely to be regulated in a different and more complex manner than that of arterial blood velocity. Mode of delivery does not affect cerebral blood velocity. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
On‐line Quality Control of Coated Glass. On‐line Qualitätskontrolle von beschichtetem Glas
Authors: List M. , Melde C. , Krause J. , Köckert C.
Published: October 2004

Eigenschaften von optischen Schichten, wie z. B. Wärmedämm‐ oder Sonnenschutzschichten, können in der Glasindustrie durch die Messung von Transmission, Reflexion und Flächenwiderstand beschrieben und kontrolliert werden. Verschiedene in situ Transmissionsmessstellen erlauben eine schnelle Rückkopplung zu den einzelnen Beschichtungsprozessen (Schichtdicke und ‐gleichmäßigkeit). Die abschließende Charakterisierung des beschichteten Glases erfolgt durch eine traversierbare ex situ Messung von Transmission, Reflexion und Flächenwiderstand. Präzise und reproduzierbare Messungen erlauben die Anwendung von Reverse Engineering Methoden zur exakten Bestimmung aller Schichtdicken und zur Erkennung von Driften während des Produktionsprozesses.
Experience with Radical esophagogastric devascularization procedures (Sugiura) for variceal bleeding outside Japan
Authors: Dagenais Michel , Langer Bernard , Taylor Bryce R. , Greig Paul D.
Published: October 2004

The Sugiura operation has been reported to have low operative mortality, rebleeding, and encephalopathy rates when carried out in a predominantly nonalcoholic Japanese population with good liver function. A literature review of reports of the Sugiura procedure outside Japan reveals a high complication and mortality rate when it is used as an emergency procedure in patients with advanced liver disease, especially in those with alcoholic cirrhosis. Uncontrolled studies report results that differ little from the Japanese series when the operation is confined to good‐risk patients in the elective situation. Our experience with the Sugiura operation supports its role in these circumstances, especially in patients with portal vein thrombosis and normal liver function. The only good prospective controlled trial has been carried out in patients with schistosomiasis and suggests that the Sugiura operation is far superior to total shunt and may have a slight advantage over the Warren shunt because of its low incidence of postoperative encephalopathy. More controlled trials are required to establish its role in good‐to moderate‐risk patients with alcoholic cirrhosis.
Role of surgical therapy in management of intractable ascites
Authors: Elcheroth Feanny , Vons Corinne , Franco Dominique
Published: October 2004

Almost 10% of patients with cirrhosis and ascites develop intractable ascites. When large‐volume paracentesis fails to relieve aseites, patients may be submitted to one of the three following surgical options: portosystemic shunting, peritoneovenous shunting, or liver transplantations Portosystemic shunting is efficient in clearing ascites, but it is associated with a high rate of encephalopathy and liver failure. The adications for portosystemic shunting are therefore limited for treatment of intractable ascites and should be performed only in patients with good liver function in whom all other treatments failed. Peritoneovenous shunting has been associated with a high rate of early complications and calve obstruction. Improvements in perioperative care and in the material used have greatly reduced the operative risks and increased the patency rate. Mortality remains high in patients with severe liver failure or with history of spontaneous bacterial peritonitis or variceal bleeding. Peritoneovenous shunting should not be done when these risk factors are present. In the absence of such risk factors; peritoneovenous shunting is in good procedure and may provide definitive relief of ascites and long‐term survival in more than 50% of the operated patients. In patients with poor risk factors liver transplantation may be preferable, and the onset of intractable ascites in a patient with a severely compromised liver should trigger the indication of liver replacement.
Molecular biology of gastric cancer
Authors: Tahara Eiichi
Published: October 2004

Gastric cancer involves changes in multiple oncogenes and multiple suppressor genes, and it causes genetic instability. Aberrant expression and amplification of the c‐met gene, inactivation of the p53 gene, and CD44 abnormal transcripts are common events of both well differentiated and poorly differentiated gastric cancers. Amplification of the cyclin E gene is also observed in gastric cancer regardless of histologic type. Decreased expression of the pic1 (p21) gene occurs independent of the p53 mutations. In addition, K‐ras mutations, c‐erbB‐2 gene amplification, loss of heterozygosity (LOH) and mutations of the APC gene, LOH of the bcl‐2 gene, and LOH at the DCC locus are preferentially associated with well differentiated gastric cancer. Moreover, LOH on chromosome 1q is involved in the progression of well differentiated cancer. Precancerous lesions, including hyperplastic polyp, intestinal metaplasia, and adenoma, share genetic changes found in well differentiated cancers. Conversely, genetic instability may be involved in the first step of stomach carcinogenesis of the poorly differentiated type. Reduction or loss of cadherin and catenins, K‐sam gene amplification, and c‐met gene amplification are necessary for the development and progression of poorly differentiated or scirrhous carcinoma. Interaction between cell‐adhesion molecules in the c‐met expressed tumor cells and hepatocyte growth factor from stromal cells is implicated in the morphogenesis of two types of gastric cancer. Taken together, different genetic pathways of stomach carcinogenesis may exist for well differentiated and poorly differentiated gastric cancers. Some of the former may develop by a cumulative series of gene alterations similar to those of colorectal cancer. Peritoneal dissemination and metastasis may require LOH on chromosome 7q, reduction in nm23 protein, abnormal transcripts of CD44, changes in cadherin and catenins, and overexpression of a 31‐kDa lactoside‐binding lectin.
News of TNM and its use for classification of gastric cancer
Authors: Hermanek P. , Wittekind C.
Published: October 2004

Tumor classification is associated with two inherent problems: (1) to find a compromise between the simplicity needed for a wide application by the medical community and sufficient differentiation and specification required for the presently high differentiation in treatment options and for detailed analysis of treatment results; and (2) to achieve an agreement between the stability necessary for data collection over long periods and the needed continuous inclusion of new proposals that arise by advances in diagnostic and therapeutic methods and the increasing knowledge of prognostic factors. The aim of this report is to inform on the changes and expansions of the international classification of gastric carcinoma during the last few years, to refer to new developments, to point out the relations between established classifications and molecular biology, and to show the future trend in tumor classification.
Intraoperative radiation therapy for gastric cancer
Authors: Abe Mitsuyuki , Nishimura Yasumasa , Shibamoto Yuta
Published: October 2004

From among 115 patients who were treated by intraoperative radiation therapy (IORT), 94 patients were classified according to the histologic findings. The control 127 patients who were treated by operation alone during the same period were also histologically classified, and survivals were compared between the two groups. No difference in the survivals of patients with stage I was observed for the two groups. On the other hand, the survivals of patients with stages II through IV who were treated by IORT increased by nearly 10% to 20% at 5 years. A comparative study was also performed on the survivals between patients treated by IORT and those treated by operation alone according to the presence or absence of the serosal invasion and the grade of the lymph node metastasis. The number of patients treated by IORT in whom the serosal invasion and the lymph node metastasis were histologically examined was 57. The 171 control patients who underwent operation alone were examined histologically in the same fashion, and survivals for the two groups were compared. IORT did not afford any benefit if the lymph node metastasis was limited within n1 group or serosal invasion was not found. On the other hand, the 5‐year survival rates for patients who were treated by IORT increased by nearly 10% when the serosal invasion was observed and by nearly 18% when n2 and n3 lymph node metastases were found.
Prophylaxis and treatment of peritoneal carcinomatosis: Intraperitoneal chemotherapy with mitomycin C bound to activated carbon particles
Authors: Takahashi Toshio , Hagiwara Akeo , Shimotsuma Masataka , Sawai Kiyoshi , Yamaguchi Toshiharu
Published: October 2004

A novel method of prophylaxis and treatment for peritoneal carcinomatosis—mitomycin C bound to activated carbon particles (MMC‐CH)—was tested in patients with advanced gastric cancer in a prospective randomized study. Activated carbon particles are taken up selectively by lymphatic tissues, which seem to be a primary site of peritoneal carcinomatosis in the peritoneal cavity, and adsorb a large amount of anticancer agent mitomycin C, which is subsequently released slowly and for a protracted period. A group of 113 patients who underwent radical resection for gastric cancer with definite serosal involvement were entered in this trial. Those in the control group received no intraperitoneal anticancer drugs. Patients in the MMC‐CH group were given 50 mg mitomycin C as MMC‐CH, which was dispersed throughout the peritoneal cavity just before surgical closure. No other anticancer drugs were given to these patients after surgery. The 2‐ and 3‐year survival rates for the MMC‐CH group were 42% and 38%, respectively; and the rates for the control group were 28% and 20%, respectively. The difference in survival between the two groups was significant at 2 and 3 years (p<0.05). For the survival of patients with macroscopic peritoneal carcinomatosis, there was no difference between these two groups. For the survival of patients who underwent histologically curative resection, 2‐ and 3‐year survivals for the MMC‐CH group were 66% and 66%, respectively and for the control group 35% and 20%, respectively. The difference between the two groups was statistically significant (p<0.01) at both 2 and 3 years. There was no difference in morbidity after surgery between these two groups, except a bowel (colocutaneous) fistula developed in two patients given MMC‐CH. There were no operative deaths in this series.
Hepatolithiasis associated with cholangiocarcinoma
Authors: Kubo Shoji , Kinoshita Hiroaki , Hirohashi Kazuhiro , Hamda Hiroyuki
Published: October 2004

Hepatolithiasis is a risk factor for cholangiocarcinoma. It is difficult to make an accurate diagnosis before treatment. In a retrospective study, we identified characteristic clinical features of 103 patients with hepatolithiasis (group H) and 10 patients with hepatolithiasis associated with cholangiocarcinoma (group HC), and examined the methods for diagnosis and treatment. The main symptoms were abdominal pain, fever, and jaundice, although few patients in group HC had jaundice. The incidence of abnormal serum levels of carcinoembryonic antigen (CEA) in group HC was higher than in group H. The incidence of cholangiocarcinoma in cases in which most of the stones were present in the intrahepatic ducts of the left lobe (type I‐L) was higher than the incidence in the other patients. Of the patients who underwent portography in group HC, portal veins in the portion of the liver containing the cholangiocarcinoma were not seen, and this region was atrophic in the operative specimens. The incidence of portal obstruction in portograms in group HC was higher than that in group H. The possibility of carcinoma should be kept in mind if there are high levels of CEA, if the location of the stones is classified as type I‐L, or if portal veins cannot be seen on portograms. In such patients, liver resection should be considered because there may be undiagnosed cholangiocarcinoma.
Early recurrence of hyperthyroidism in patients with Graves' disease treated by subtotal thyroidectomy
Authors: Sugino Kiminori , Mimura Takashi , Ozaki Osamu , Kure Yoshio , Iwasaki Hiroyuki , Wada Nobuyuki , Matsumoto Akihiko , Ito Kunihiko
Published: October 2004

Prerequistes for surgical treatment of Graves' disease are that it can be done safely and that it is associated with a low incidence of recurrent hyperthyroidism. Early recurrence is especially undesirable. We studied 728 patients with Graves' disease treated by subtotal thyroidectomy using multivariate analysis in order to determine the factors related to early recurrence. The following factors were analyzed: age, sex, duration of medical treatment, weight of resected thyroid tissue, thyroid remnant size, preoperative level of thyroid‐stimulating hormone (TSH) binding inhibitory immunoglobulin (TBII), and antimicrosomal hemagglutination antibody (MCHA). “Early recurrence” was defined as TSH suppression observed within the first year after surgery and continuing for at least 6 months. A total of 106 patients (14.6%) had early recurrence. Statistical analyses were performed by the chi‐square test for univariate analysis and a logistic model for multivariate analysis. Significant factors were thyroid remnant size, MCHA, and TBII. These results indicated that TBII and MCHA are related to early recurrence of hyperthyroidism, and smaller remnant size is recommended for patients with a high MCHA titer or a high TBII level (or both) in order to avoid early recurrence.
Comparison of cefotaxime plus metronidazole versus cefoxitin for prevention of wound infection after abdominal surgery
Authors: Kow Lilian , Toouli James , Brookman Judith , McDonald Peter James
Published: October 2004

In a randomized prospective stratified trial consisting of 1010 patients undergoing abdominal surgery involving the viscera, the efficacy of cefotaxime plus metronidazole was compared to cefoxitin for preventing wound infection. The efficacy of a single dose of antibiotics versus three doses over 24 hours was also evaluated. This study demonstrated that a single‐dose antibiotic regimen was as effective as a multiple‐dose regimen in the prophylaxis of wound infections following abdominal surgery. In addition it demonstrated that the cefotaxime plus metronidazole regimen is comparable to that of cefoxitin and is more cost‐effective. It is concluded that a single dose of cefotaxime plus metronidazole provides effective prophylaxis against postoperative wound infections following abdominal surgery.
Survival after resection of gastric cancer and prognostic relevance of systematic lymph node dissection: Twenty years experience in Taiwan
Authors: Lee Wei‐Jei , Lee Wen‐Chung , Houng Shyh‐Jinn , Shun Chia‐Tung , Houng Ren‐Long , Lee Po‐Hung , Chang King‐Jen , Wei Ta‐Cheng , Chen Kai‐Mo
Published: October 2004

A retrospective study of 954 resectable gastric cancers in a single institute of Taiwan from 1971 to 1990 was performed to evaluate improvements in gastric cancer surgery. The patients were divided into four time periods representing an overall experience of progressive implementation of aggressive resection and increased extent of systematic lymph node dissection. The clinicopathologic data and survival rates were statistically compared and the significance of the extent of resection on survival analyzed. A significant increase in the proportion of upper one‐third tumors (from 14.8% to 20.4%) and a decrease in the incidence of intestinal type (73.6% to 41.5%) was found within the overall period. The proportion of patients with early gastric cancer increased from 11.5% to 19.4%. Patients who underwent total gastrectomy and combined visceral resection increased from 13.7% to 27.4% and 19.8% to 41.1%, respectively. An increase of both total dissected lymph, node number and the incidence of detected lymph node metastases in early gastric cancer were associated with more extensive lymphadenectomy. An improved 5‐year survival rate following aggressive resection was found for all stages except stage IV and T4 lesions, and the surgical mortality decreased from 5.5% to 2.0%. Patients with earlier stage lesions benefited more from radical resection, especially those with stage II and T2 lesions. Systematic lymph node dissection increased the 5‐year survival of patients by about 10% for stage III or T3 lesions, but not for patients with stage IV or T4 lesions. Multivariate analysis confirmed the significance of the improved technique of lymphadenectomy on the prognosis of gastric cancer following resection in Taiwan. In conclusion, a changing pattern of gastric cancer epidemiology in Taiwan is documented. A decrease in surgical mortality indicates that curative resection with extensive lymph node dissection can be safely performed. Although potential for increasing survival by upstaging remains, radical gastrectomy with extended lymphadenectomy could be adopted for gastric cancer resection with possibly more adequate control of locoregional disease.
Management of intrabiliary rupture of hydatid cyst of the liver
Authors: Ulualp Kenan M. , Aydemir Ismail , Senturk Hakan , Eyuboğlu Erhun , Cebeci Hayrettin , Unal Gurcan , Unal Hilal
Published: October 2004

Thirty‐six patients with intrabiliary rupture of hepatic echinococcal cysts were managed between 1974 and 1993. Clinical findings, skin tests, serologic tests, and imaging techniques were used to establish the diagnosis. Twenty‐five (69.4%) patients had pain, 24 (66.6%) jaundice 22 (61.1%) fever, 20 (55.5%) chills, 10 (27.7%) malaise, and 7 (19.4%) other symptoms as the major causes of admission. All patients underwent choledochotomy and T‐tube drainage. Treatment directed to the cyst was cystectomy and capittonage, cystectomy and drainage, and partial hepatectomy in 22, 12, and 2 patients, respectively. Omentoplasty was added to the treatment in 10 patients. Seven (19.4%) patients had complications. The period of hospitalization for patients with and without complications was 34.6±18.1 and 15.1±2.7, days, respectively. This study indicates that better results are obtained in patients with cystic lesions of the liver by avoiding percutaneous puncture or biopsy, the early use of ultrasonography and computed tomography, evacuation of the cyst together with its germinative membrane and the involved biliary tract under adequate care to avoid spillage into the peritoneal cavity, treating the remaining cavity according to its location, size, and the presence of infection, and decreasing the pressure in the biliary tract by T‐tube drainage.
Childhood melanoma in Australia
Authors: McWhirter W. R. , Dobson C.
Published: October 2004

Data from a population‐based registry, the Australian Paediatric Cancer Registry, were used to determine the incidence of malignant melanoma in children under 15 years of age in Australia. Over a 17‐year period, 217 cases were identified. For the period 1977–89 inclusive, the annual age incidence was 0.34 per 100,000. There was some variation in incidence between the different states with Queensland recording the highest incidence at 0.97 per 100,000, the highest reported incidence in the world for childhood melanoma. Most of the cases occurred in children aged 13 or 14 years old with girls affected slightly more often, the sex ratio being 0.92. There was a statistically significant seasonal variation with fewer cases being diagnosed during the winter months. The commonest site was the trunk. Two of the cases were second neoplasms. This series demonstrates the need for increased education of children living in tropical and subtropical regions about the dangers of sun exposure and of methods of reducing exposure. Children who have undergone chemotherapy appear to be at particular risk.
Radiation therapy for nodal disease in malignant melanoma
Authors: Burmeister B. H. , Smithers B. M. , Poulsen M. , McLeod G. R. , Bryant G. , Tripcony L. , Thorpe C.
Published: October 2004

Radiation therapy has been widely used for palliative management of inoperable metastatic malignant melanoma. For patients with nodal disease, response rates of approximately 70% have been reported. There are limited data concerning the role of adjuvant irradiation following therapeutic lymph node dissection. In this review, 57 patients with isolated resectable and nonresectable nodal disease have been treated with radiation. The overall response rate is 84% for bulky disease. Large fractions are beneficial. The median disease‐free survivals were 11 months after adjuvant treatment and 7 months for those with inoperable disease. The median overall survivals were 20 months and 18 months, respectively. Local control in long‐term survivors was excellent. Sixty‐five percent of patients developed distant metastases. There is a need for additional studies with the use of adjuvant radiation therapy following lymph node dissection.