bluuebunny/crossref_metadata_2025 huggingface dataset:
Versatile Phosphite Ligands Based on Silsesquioxane Backbones
Authors: van der Vlugt Jarl Ivar , Ackerstaff Jens , Dijkstra Tessa W. , Mills Allison M. , Kooijman Huub , Spek Anthony L. , Meetsma Auke , Abbenhuis Hendrikus C. L. , Vogt Dieter
Published: April 2004

Silsesquioxanes are employed as ligand backbones for the synthesis of novel phosphite compounds with 3,3′‐5,5′‐tetrakis(tert‐butyl)‐2,2′‐dioxa‐1,1′‐biphenyl substituents. Both mono‐ and bidentate phosphites are prepared in good yields. Two types of silsesquioxanes are employed as starting materials. The monophosphinite 1 and the monophosphite 2 are prepared from the thallium silsesquioxide derived from a completely condensed silsesquioxane framework (c‐C5H9)7Si7O12SiOTl. The diphosphite 3 is synthesized starting with the incompletely condensed monosilylated disilanol (c‐C5H9)7Si7O9(OSiMePh2)(OH)2. For monophosphite 2, the corresponding trans‐[PtCl2(2)] complex 4 is characterized by NMR spectroscopy as well as by X‐ray crystallography, as the first example of a completely condensed oxo‐functionalized silsesquioxane framework. The coordination of the bidentate ligand 3 towards Pd, Mo and Rh is studied, both by NMR spectroscopy as well as by X‐ray crystallography. Various modes of coordination are shown to be possible. The molecular structures for the complexes trans‐[PdCl2(3)] (5), cis‐[Mo(CO)4(3)] (6) and the dinuclear complex [{Rh(μ‐Cl)(CO)}2(κ2‐3)] (7) have been determined. In the rhodium‐catalyzed hydroformylation of 1‐octene high activities, with turnover frequencies of up to 6800 h−1, are obtained with these new nanosized phosphorus ligands.
Gold Catalysis: Mild Conditions for the Transformation of Alkynyl Epoxides to Furans
Authors: Hashmi A. Stephen K. , Sinha Pradipta
Published: April 2004

Gold(III) chloride catalyzes the isomerization of alkynyl epoxides to furans under mild conditions. Additional functional groups like hydroxy groups or aryl bromides do not need to be protected.
Effect of distribution tabs on mass transfer of artificial kidney
Authors: Ding Weiping , He Liqun , Zhao Gang , Luo Xiaodong , Zhou Min , Gao Dayong
Published: April 2004

The configuration of the dialysate inlet and outlet is one of the main factors that affect the mass transfer performance of the artificial kidney. The effect of the distribution tabs at the dialysate inlet and outlet on mass transfer is investigated qualitatively by means of three‐dimensional (3‐D) flow field numerical simulation. The nonporous tabs are designed to be the porous tabs. Then the variation of the artificial kidney's clearance is studied with the porous tabs' Darcy permeability decreasing from +∞ to 0. The results show that the clearance first increases slightly, and then rises sharply; after arriving at a maximum, the clearance falls sharply and then decreases steadily. From the results, the optimal Darcy permeability of the porous tabs is found, corresponding to which the maximal clearance is about 4.5% higher than the current artificial kidney's clearance under the same conditions. The results are very significant for designers to improve the artificial kidney. 2004 American Institute of Chemical Engineers AIChE J, 50: 786–790, 2004
Modeling hydrogen spillover in dual‐bed catalytic reactors
Authors: Weigle John C. , Phillips Jonathan
Published: April 2004

A semiquantitative model was developed to describe hydrogen spillover in dual‐bed catalytic reactors. In previous studies it has been conclusively demonstrated that hydrogen can diffuse macroscopic distances and activate catalytic sites. The test reaction in those studies was the isomerization of 1‐butene to 2‐butene. The model is derived based on the fundamental principles of transport phenomena and reaction kinetics. Because many of the required values in the model are unknown, it cannot be solved quantitatively. Thus, a parametric analysis was conducted. The model successfully predicts trends observed experimentally. Specifically, the activity increases nonlinearly as the bed composition changes, the selectivity was low for all dual‐bed reactors, and the selectivity was high for well‐mixed catalyst beds. © 2004 American Institute of Chemical Engineers AIChE J, 50: 821–828, 2004
Occupation and risk of meningioma and acoustic neuroma in the United States
Authors: Rajaraman Preetha , Roos Anneclaire J. De , Stewart Patricia A. , Linet Martha S. , Fine Howard A. , Shapiro William R. , Selker Robert G. , Black Peter M. , Inskip Peter D.
Published: April 2004

Background

Workplace exposures may be related to the development of brain tumors. In this case‐control study, we examine occupation as a risk factor for meningioma and acoustic neuroma.

Methods

A lifetime work history was obtained for 197 incident cases of meningioma, 96 cases of acoustic neuroma and 799 controls with non‐malignant diseases enrolled from three hospitals in the United States between 1994 and 1998. Jobs considered to have similar tasks and chemical exposures were assigned to an occupational group. Logistic regression was used to estimate odds ratios (OR) adjusted for study matching factors (hospital, age, sex, race/ethnicity, and proximity of residence to the hospital) and education.

Results

Elevated risk of meningioma was observed for individuals who had ever worked in the following occupational groups: auto body painters, designers and decorators, military occupations, industrial production supervisors, teachers, and managers. For acoustic neuroma, increased risk was noted for having worked as an athlete, gas station attendant, purchasing agent, sales representative, or teacher.

Conclusions

Although limited by multiple comparisons and the relatively small number of cases and controls in many occupational groups, these results nevertheless provide clues that deserve additional study in future epidemiologic studies. Am. J. Ind. Med. 45:395–407, 2004. Published 2004 Wiley‐Liss, Inc.
Mutagenic testing of workers exposed to toluene‐diisocyanates during plastics production process
Authors: Bilban Marjan
Published: April 2004

Background

Toluene diisocyanates (TDIs) are important industrial intermediates used in conjunction with polyester polyols as coreactants in the manufacture of polyurethane foam blocks, paints, etc. It is listed as a potential carcinogen by the National Toxicology Program (NTP) and International Agency for Research on Cancer (IARC) and is known to induce chromosomal aberrations.

Methods

The study involved 26 people, exposed to TDI during the production of plastics. The corresponding control group was comprised of 21 people coming from the same geographic area, who were never exposed to isocyanates.

Results

The concentration of TDI ranged between 0.007 mg/m3 and 0.016 mg/m3, which amounts to 0.10–0.23 MDK (extreme value of a single substance) 0.007 mg/m3. Structural chromosome aberrations (SCA) were evaluated in 200 lymphocytes of peripheral blood. The average value was 2.6. Sister chromatid exchange (SCE) was established in 50 cells, the average being 8.127. Micronucleus (MN) was established in 500 CB, with an average of 12.07. The averages of the control group were 1.89 (SCA), 5.52 (SCE), and 4.38 (MN). The difference between the groups is of statistical significance.

Conclusions

The ascertained results accentuate mutagenic activity of isocyanates or their metabolic products. Am. J. Ind. Med. 45:468–474, 2004. © 2004 Wiley‐Liss, Inc.
The psychosocial work environment and musculoskeletal disorders: Design of a comprehensive interviewer‐administered questionnaire
Authors: Rugulies Reiner , Braff Jeffrey , Frank John W. , Aust Birgit , Gillen Marion , Yen Irene H. , Bhatia Rajiv , Ames Genevieve , Gordon Deborah R. , Janowitz Ira , Oman Doug , Jacobs Bradly P. , Blanc Paul
Published: April 2004

Background

Psychosocial working conditions are likely to contribute to work‐related musculoskeletal disorders (WRMSDs), but a lack of standardized measurement tools reflects both the theoretical and methodological limitations of current research.

Methods

An interdisciplinary team including biomedical, behavioral, and social science researchers used an iterative process to adapt existing instruments for an interviewer‐administered questionnaire assessing psychosocial workplace exposure related to musculoskeletal disorders.

Results

The resulting questionnaire included measures of psychosocial workplace factors based on two theoretical models (the demand‐control‐support and the effort‐reward imbalance models), supplemented by the additional constructs of “emotional demands,” and “experiences of discrimination.” Other psychosocial and physical measures selected for questionnaire inclusion address physical workload, sociodemographic and anthropometric characteristics, social relations and life events, health behaviors, and physical and psychological health.

Conclusion

Using an interdisciplinary approach facilitated the development of a comprehensive questionnaire inclusive of key measures of psychosocial factors that may play a role in the complex mechanisms leading to WRMSDs. Am. J. Ind. Med. 45:428–439, 2004. © 2004 Wiley‐Liss, Inc.
Unilateral nerve injury produces bilateral loss of distal innervation
Authors: Oaklander Anne Louise , Brown Jennifer M.
Published: April 2004

There are no known anatomical connections between neurons that innervate homologous right and left body parts. Nevertheless, some patients develop bilateral abnormalities after unilateral injury, a phenomenon often unrecognized and not yet characterized. Therefore, we examined in rats the effects of ligating and cutting one tibial nerve on sensory function and on density of innervation in hind paws contralaterally as well as ipsilaterally to the injury, at times between 1 day and 5 months after surgery. Punches removed from tibial‐ or sural‐innervated planter paw skin were immunolabeled to quantitate epidermal nerve endings. Naive and sham‐operated rats provided controls. Axotomized rats had near‐total loss of PGP9.5+ innervation within ipsilateral tibial‐innervated skin at all time‐points. Adjacent ipsilateral sural‐innervated skin had persistent hyperalgesia without denervation, and robust axonal sprouting at 5 months after surgery. Contralesional hind paws lost 54% of innervation in tibial‐innervated epidermis starting 1 week after surgery and persisting throughout. Contralesional sural‐innervated skin had neither neurite loss nor sprouting. These results imply that unilateral nerve injury can cause profound, long lasting, nerve–branch–specific loss of distal innervation contralaterally as well as ipsilaterally. They discredit the practice of using tissues contralateral to an injury to provide normative controls and suggest the possibility of rapid, transmedian postinjury signals between homologous mirror‐image neurons.
Use of cationic starch derivatives for the removal of anionic dyes from textile effluents
Authors: Khalil Mohamed I. , Aly Amal A.
Published: April 2004

Six types of cationic starch derivatives were prepared. These types were (1) cationic starch derivatives containing primary, secondary, and tertiary amino groups and quaternary ammonium salt and (2) etherified and grafted cationic starch derivatives. These cationic starch derivatives were treated with three types of dyes, an acid dye, a hydrolyzed reactive dye, and a direct dye. Different factors affecting the dye sorption value (mmol/100 g of sample) were been studied. These factors were the pH of the medium, treatment time, amine type, amine content, dye type and molecular size, and the distance between the amine groups. The dye sorption value and the sorption efficiency percentage were determined. The dye sorption value increased with increasing amine content to a maximum value and then decreased. This phenomenon occurred with all of the amine types. The maximum dye sorption values on with the acid dye depended on the amine type. These values were 73.8 (at an amine content of 155), 90 (at an amine content of 150), 84.9 (at an amine content of 133), and 72.5 (at an amine content of 75) for primary, secondary, and tertiary amines and the quaternary ammonium salt, respectively. The sorption efficiency percentage at these maximum values were 47.6, 60, 63.8, and 96.3%, respectively. The maximum sorption values were acid dye > hydrolyzed reactive dye > direct dye. The dye sorption value and the sorption efficiency percentage of the etherified cationic starch derivatives had higher values than that of the grafted cationic starch derivatives. The prepared cationic starch derivatives that had amine contents of 155, 150, 133, and 75 m atom/100 g of sample for primary, secondary, and tertiary amines and the quaternary ammonium salt, respectively, had the best ability to adsorb anionic dyes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 227–234, 2004
Polyimides. IV. Synthesis and characterization of fluorinated copolyimides
Authors: Madhra Mukesh Kumar , Sharma Mamta , Banerjee Susanta
Published: April 2004

A series of new copolyimides were synthesized by the reaction of pyrometallic dianhydride, benzophenone tetracarboxylic acid dianhydride, and 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA) with two diamines, 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl and 4,4′‐diaminodiphenyl ether, at a 50:50 ratio by a thermal imidization route. The complete spectral assignment of the copolymer derived from 6FDA was done with the help of distortionless enhancement of polarization transfer 90° and two‐dimensional heteronuclear (C, H) shift correlation spectroscopy. The various types of couplings in the copolymers were assigned with the help of two‐dimensional correlated spectroscopy (COSY) homonuclear correlation spectroscopy. A long‐range connectivity was also observed by a heteronuclear correlation spectroscopy via long‐range coupling experiment. The copolyimides derived from 6FDA were soluble in common organic solvents such as N,N‐dimethyl formamide, N,N‐dimethyl acetamide, dimethyl sulfoxide, N‐methyl pyrrolidone, and chloroform. Water absorption values, after the samples were boiled in water for 72 h, were in the range 0.3–0.7%. These polyimides had low dielectric constants of 2.79–3.01 at 1 MHz, low refractive indices of 1.655–1.705 at 589.3 nm, and high optical transparencies (>90%). The onset temperature for 5% weight loss for these polyimides, as assessed by thermogravimetric analysis, was up to 551°C in air, indicating a very high thermal stability, and the polyimides showed glass‐transition temperatures as high as 316°C. Transparent thin films of these polyimides exhibited tensile strengths up to 93 MPa, moduli of elasticity up to 3.1 GPa, and elongations at break up to 24% depending on the exact repeat unit structure. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 235–246, 2004
Modeling of the copolymerization, with depropagation, of α‐methyl styrene and methyl methacrylate at an elevated temperature
Authors: Cheong Seong Ill , Penlidis A.
Published: April 2004

We propose a dynamic model for the copolymerization of α‐methyl styrene (α‐MS) and methyl methacrylate (MMA) in a batch reactor. The parameters are based on data from the literature and our own laboratories over the full conversion range. A two‐parameter model with constant reactivity ratios shows the most reasonable results. The dynamic model depicts the reaction kinetics and reactor behavior more clearly. Termination occurs mainly by the cross reaction of unlike radicals, and its rate increases with the molar ratio of α‐MS to MMA. The model enables us to predict the instantaneous and cumulative properties of the copolymer and also provides us with a basic tool for the optimization and control of industrial reactors. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 261–270, 2004
Adhesion between dissimilar polymers. II. Effects of bonding temperature and crosslinking agent
Authors: Tse M. F. , Hu W. , Yeganeh M. S. , Zhang D.
Published: April 2004

We study the effects of bonding temperature and crosslinking agent on the adhesion of a crosslinkable BIMS polymer (terpolymer of isobutylene, p‐bromomethylstyrene, and p‐methylstyrene) to a crosslinkable diene polymer, such as polyisoprene rubber (IR) or polybutadiene rubber (BR). The strength of adhesion between these two dissimilar polymers, represented by the work of detachment, Ga, is measured by using the T‐peel geometry at various test temperatures and separation speeds. Surface‐sensitive infrared‐visible sum frequency generation (SFG) spectroscopy is used to characterize the surface of BIMS and ensure the existence of crosslinkable species, the p‐bromomethylstyrene functional group, on this polymer. Time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS) is utilized to determine the loci of failure of the debonded surfaces and the influence of curative migration, if any, on adhesion. Although a zinc di‐2‐ethylhexanoate crosslinkable BIMS polymer shows interfacial crosslinking or cocure when bonded to a sulfur crosslinkable diene polymer at 140°C, interfacial cocure does not occur when the bonding temperature is raised to 180°C. On the other hand, if the sulfur crosslinking agent in the diene polymer is replaced by another crosslinking agent, a brominated phenolic resin, interfacial cocure occurs between BIMS and the diene polymer when the bonding temperature is 140, 160, or 180°C. Also, this brominated resin cocures the BIMS and diene polymer phases when these immiscible polymers are blended together in the presence of a metal compound (salt) of carboxylic acid, such as zinc di‐2‐ethylhexanoate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 323–335, 2004
Crystallization behavior of poly(N‐methyldodecano‐12‐lactam). III. Kinetics of isothermal crystallization
Authors: Kratochvíl J. , Sikora A.
Published: April 2004

Differential scanning calorimetry, combined with Avrami theory, was used to investigate the kinetics of three steps of the complex crystallization process of poly(N‐methyldodecano‐12‐lactam) (MPA): (1) primary melt crystallization at respective crystallization temperature (Tc), (2) additional crystallization at 30°C, and (3) recrystallization at 54°C. Kinetics of the three steps was discussed with respect to Tc. The Avrami exponent n of primary melt crystallization decreased between 2.5 and 1.9 in the range of Tc values of −10 to 20°C, which suggests heterogeneous nucleation, followed by two‐dimensional growth, with a larger involvement of homogeneous thermal nucleation at greater supercoolings. The crystallization rate constant k decreased with increasing Tc. The value of n = 1.5 for additional crystallization implies a two‐dimensional diffusion‐controlled crystal growth with a suppressed nucleation phase. For Tc values ranging from −10 to 0°C and 0 to 20°C, k showed weak and quite strong decreasing dependencies on Tc, respectively. The recrystallization mechanism involved partial melting of primary crystallites and two‐dimensional rearrangement of chains into a more perfect structure. The rate of this process was almost independent of Tc. The values of activation energies were derived for the three steps of MPA crystallization using the Arrhenius equation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 279–293, 2004
Structural changes of injection molded starch during heat treatment in water atmosphere: Simultaneous wide and small‐angle X‐ray scattering study
Authors: Cagiao M. E. , Rueda D. R. , Bayer R. K. , Baltá Calleja F. J.
Published: April 2004

Native starches with wide varying amylose content were processed by injection molding. The injection‐molded materials were conditioned in water for 20 days and sealed in glass capillaries. Simultaneous wide‐ and small‐angle X‐ray scattering (WAXS and SAXS, respectively) were recorded during thermal heating using a synchrotron source. Crystallinity, SAXS invariant, Q, and long period, L, were measured as a function of heating temperature. The injection‐molding process provokes a destruction of the crystal forms A (cereal starch) and B (tubercle starch) but favors a development of the crystal form Vh. After wet conditioning, WAXS of the injection‐molded samples shows again the appearance of the crystal forms A or B, and crystallinity reaches values similar or larger than those of native starch. A constant heating rate (5°C/min) was particularly used for a comparison of potato and corn starch with a similar amylose content. While the crystallinity associated to forms A and B slowly decreases below 55°C and then rapidly decreases until its disappearance at 85–90°C, the invariant shows a maximum around 40°C and rapidly decreases thereafter. The total nanostructure disappearance occurs at temperatures about 10°C higher for the case of potato starch. In addition, a recovery of the WAXS and SAXS maxima during the subsequent cooling process before reaching room temperature was observed only for potato starch. Analysis of WAXS and SAXS for the rest of the starch materials reveals clear differences in the structural parameters of the samples that cannot be easily explained solely on the basis of the amylose content. Thus, for Cerestar and Roquette, it is noteworthy that there was a continuous decrease of L until its total disappearance as well as the persistence of crystallinity (form B), presumably stabilized by the presence of the Vh structure (12–15%). Real‐time crystallization experiments on two amorphous injection molded samples, waxy maize (free amylose starch) and potato starch, are also discussed. It is shown that the absence of amylose delays the recrystallization of amylopectine during the experiment. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 301–309, 2004
On rotation, torsion, lateralization, and handedness of the embryonic heart loop: New insights from a simulation model for the heart loop of chick embryos
Authors: Männer Jörg
Published: April 2004

The internal organs of vertebrates show specific anatomical left‐right asymmetries. The embryonic heart is the first organ to develop such asymmetries during a process called dextro‐looping. Thereby the initially straight heart tube curves toward its original ventral side and the resulting bend becomes displaced toward the right side of the embryo. Abnormal displacement of the heart loop toward the left is rare and is called levo‐looping. Descriptive studies have shown that the lateralization of the heart loop is driven by rotation around its dorsal mesocardium. However, nothing was known on the modes of this process. To gain insight into this subject, different modes of rotation were tested in a simulation model for the looping chick embryo heart. The morphological phenotypes obtained in this model were compared with normal and mirror‐imaged embryonic hearts. The following observations were made. One, rotation of the heart loop around its dorsal mesocardium has two consequences: first, lateral displacement of its bending portion either toward the right (D‐loop) or left (L‐loop) side of the embryo, and second, torsion of the cardiac bend into a helical structure that is wound either clockwise (right‐handed helix) or counterclockwise (left‐handed helix). The normal loop presents as a D‐loop with left‐handed helical winding and its mirror image presents as an L‐loop with right‐handed helical winding. This conflicts with the use to define D‐loops as right‐ and L‐loops as left‐handed structures. Two, dextro‐looping might be driven almost exclusively by rightward rotation of the arterial pole of the loop. It becomes complemented by leftward rotation of the venous pole during the subsequent phase of looping. An inverse mode of rotation might drive levo‐looping. Three, the two different helical configurations of heart loops both can occur as right‐sided, median, or left‐sided positional variants. When viewed from the front, all right‐sided variants appear as D‐loops and all left‐sided variants appear as L‐loops at the end of dextro‐ or levo‐looping. Their true asymmetric phenotypes become fully apparent only after simulation of the subsequent phase of looping. The terms D‐ and L‐loop obviously do not fully define the chirality of heart loops. The chirality of their helical configuration should be defined, too. The implications of these data with respect to molecular and experimental data are discussed. Anat Rec Part A 278A:481–492, 2004. © 2004 Wiley‐Liss, Inc.
Quantitative study on guinea pig spermatogenesis shows a relative high percentage of early meiotic prophase stages
Authors: Rodríguez Rosana E. , Wettstein Rodolfo M.
Published: April 2004

Meiosis is the special double cellular division characterized by the reduction of chromosome number of the final products and recombination of genetic information present in maternal and paternal homologous chromosomes. Early stages of meiotic prophase, leptotene and zygotene (L/Z), are functionally important since homologous chromosomes recognize, align, and pair during them. They are poorly represented in the seminiferous tubules of mammalian species, and this fact turns studies focused on these stages difficult to perform. As a consequence, the molecular bases of these important events are so far poorly known and understood in higher eukaryotes. The purpose of this work was to provide an advantageous experimental mammalian model (with a reasonable number of cells) for biochemical and molecular analysis of early meiotic prophase stages. Here, we present the results of our quantitative study on testes material of both immature and adult guinea pig specimens (Cavia porcellus). We show that their seminiferous tubules contain a comparatively high percentage of L/Z spermatocytes, as well as a very conspicuous chromosome bouquet at the L/Z transition, which points out this species as a well‐suited one to address studies on such stages in mammals. Anat Rec Part A 278A:493–504, 2004. © 2004 Wiley‐Liss, Inc.
New Derivatives of Quinazoline and 1, 2‐Dihydroquinazoline N3‐Oxide with Expected Antitumor Activity
Authors: Mikiciuk‐Olasik Elżbieta , Baszczak‐Światkiewiz Katarzyna , Żurek Elżbieta , Krajewska Urszula , Różalski Marek , Kruszyński Rafał , Bartczak Tadeusz J.
Published: April 2004

Some derivatives of quinazoline and 1, 2‐dihydroquinazoline N3‐oxide were synthesised and their cytotoxic activities against human leukaemia HL‐60 cells under hypoxic and aerobic conditions were tested and compared to tirapazamine as the reference compound. Compound 8 showed 5‐fold higher toxicity under hypoxic conditions than in normal oxygen atmosphere. The structure of quinazoline derivatives was established by X‐ray crystal structure analysis.
Scrapie‐infected cells, isolated prions, and recombinant prion protein: A comparative study
Authors: Kneipp J. , Miller L. M. , Spassov S. , Sokolowski F. , Lasch P. , Beekes M. , Naumann D.
Published: April 2004

Fourier ‐transform infrared microscopic spectra of scrapie‐infected nervous tissue measured at high spatial resolution (∼6 μm) were compared with those obtained from the purified, partly proteinase K digested scrapie isoform of the prion protein isolated from nervous tissue of hamsters infected with the same scrapie strain (263K) to elucidate similarities/dissimilarities between prion structure investigated in situ and ex vivo. A further comparison is drawn to the recombinant Syrian hamster prion protein SHaPrP90–232 after in vitro conformational transition from the predominantly α‐helical isoform to β‐sheet‐rich structures. It is shown that prion protein structure can be investigated within tissue and that detectability of regions with elevated β‐sheet content as observed in microspectra of prion‐infected tissue strongly depends on spatial resolution of the experiment. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Techniques of reconstruction after total gastrectomy for cancer
Authors: Lehnert T , Buhl K
Published: April 2004

Background

Jejunal pouch formation and restoration of duodenal transit have been suggested for reconstruction after total gastrectomy. Opinions about the clinical value vary.

Methods

The literature was searched for prospective randomized trials comparing reconstructive procedures after total gastrectomy for malignancy. Reports with at least an English or German abstract were included. Immediate results were evaluated in terms of postoperative deaths and complications. Long-term outcome was analysed using trends in bodyweight and quality of life.

Results

A total of 19 randomized trials including 866 patients was identified. The operative risk of total gastrectomy was low, with a median mortality rate of 0 (range 0–22) per cent, irrespective of the method of reconstruction. Neither gastric substitution nor restoration of duodenal transit was associated with significant procedure-related complications. Results for specific reconstructions varied considerably within and between individual trials. Jejunal pouch reconstruction, but not restoration of duodenal passage, was associated with improved food intake and a tendency for weight gain in the early postoperative months. A favourable perception of quality of life persisted in the long term in some studies.

Conclusion

Preservation of duodenal transit offers little clinical benefit. Construction of a small-bowel reservoir after total gastrectomy should be considered to improve early postoperative eating capacity, bodyweight and quality of life.
Belgian experience with dynamic graciloplasty for faecal incontinence
Authors: Penninckx F
Published: April 2004

Background

Dynamic graciloplasty (DGP) is an option in patients with end-stage faecal incontinence. The aim of this retrospective multicentre study was to assess early and late outcome after DGP.

Methods

Sixty consecutive patients with congenital (14) or acquired (40) faecal incontinence or who had undergone total anorectal reconstruction (six) underwent DGP. Patients were followed up for a median of 48 (range 13–117) months.

Results

There were no deaths; 75 complications that required 61 reoperations were observed in 44 patients. Loss of muscle stimulation occurred in 22 patients, more frequently after direct nerve stimulation. Evacuation difficulties occurred in 12 patients. Overall, DGP failed in 27 patients, of whom seven had stoma construction. At follow-up, continence to solid stool without stoma was obtained in 47 of 60 patients, although 26 required use of antegrade continence enemas or other measures. Functional outcome was related to the presence of a functioning DGP and a short delay (less than 50 days) of muscle training after transposition.

Conclusion

DGP is a major operation with a high morbidity rate; it requires experience and early muscle training. The outcome after DGP should be compared prospectively with that after implantation of an artificial sphincter or other less expensive alternatives.
Oesophageal and gastric bile exposure after gastroduodenal surgery with Henley's interposition or a Roux-en-Y loop
Authors: Mabrut J-Y , Collard J-M , Romagnoli R , Gutschow C , Salizzoni M
Published: April 2004

Background

The degree which the various reconstruction techniques prevent bile reflux after gastroduodenal surgery has been poorly studied.

Methods

Bile exposure in the intestinal tract just proximal to the jejunal loop was measured with the Bilitec 2000® device for 24 h after gastroduodenal surgery in three groups of patients. Group 1 comprised 24 patients with a 60-cm Henley's loop after total gastrectomy. Group 2 included 31 patients with a 60-cm Roux-en-Y loop after total (22 patients) or subtotal (nine) gastrectomy. Group 3 contained 21 patients with a 60-cm Roux-en-Y loop anastomosed to the proximal duodenum as part of a duodenal switch operation for pathological transpyloric duodenogastric reflux. Bile exposure, measured as the percentage time with bile absorbance greater than 0·25, was classified as nil, within the range of a control population of healthy subjects, or pathological (above the 95th percentile for the control population). Reflux symptoms were scored and all patients had upper gastrointestinal endoscopy.

Results

Bile was detected in the intestine proximal to the loop in none of 24 patients in group 1, eight of 31 in group 2 and 12 of 21 in group 3 (P < 0·001). The mean reflux symptom score increased with the degree of bile exposure, and the proportion of patients with oesophagitis or gastritis correlated well with the extent of bile exposure (P < 0·001).

Conclusion

A long Henley's loop was more effective in preventing bile reflux than a long Roux-en-Y loop. Bilitec® data correlated well with the severity of reflux symptoms and the presence of mucosal lesions.
Neoadjuvant therapy for oesophagogastric cancer
Authors: Lordick F , Stein H J , Peschel C , Siewert J R
Published: April 2004

Background

The prognosis after surgery for oesophagogastric cancer remains poor.

Methods

This review clarifies current indications for neoadjuvant therapy for oesophageal and gastric cancer. A systematic literature research and evaluation of data from international cancer meetings were carried out.

Results

Recently published results of large randomized phase III trials underscore the potential value of neoadjuvant treatment for oesophagogastric cancer. However, it remains uncertain which subgroups of patients should routinely undergo preoperative therapy. Metabolic response evaluation during neoadjuvant treatment is a promising tool for the selection of responding patients.

Conclusion

Neoadjuvant chemotherapy is a valid option for locally advanced oesophageal and gastric cancer. In the future, more effective and better tolerated treatment strategies, tailored to the specific tumour characteristics of each individual, should be possible.
Aortic dissection
Authors: Safi H J , Estrera A L
Published: April 2004

In the acute setting management is primarily medical
Letter 1: Preoperative probability model for predicting overall survival after resection of pulmonary metastases from colorectal cancer (Br J Surg 2004; 91: 112–120)
Authors: Nunoo-Mensah J W , Kaiser A M
Published: April 2004

The Editors welcome topical correspondence from readers relating to articles published in the Journal. Responses can be sent electronically via the BJS website (www.bjs.co.uk) or by post. All letters will be reviewed and, if approved, appear on the website. A selection of these will be edited and published in the Journal. Letters must be no more than 250 words in length. Letters submitted by post should be typed on A4-sized paper in double spacing and should be accompanied by a disk.
Evaluation of P‐glycoprotein, HER‐2/ErbB‐2, p53, and Bcl‐2 in primary tumor and metachronous lung metastases in patients with high‐grade osteosarcoma
Authors: Ferrari Stefano , Bertoni Franco , Zanella Licciana , Setola Elisabetta , Bacchini Patrizia , Alberghini Marco , Versari Michela , Bacci Gaetano
Published: April 2004

BACKGROUND

Investigation of the relation between primary tumor and metastatic disease is necessary for the identification of predictive factors for postrecurrence survival (PRS) in patients with recurrent osteosarcoma.

METHODS

Cellular levels of P‐glycoprotein, ErbB‐2, p53, and Bcl‐2 expression were evaluated in primary tumor biopsy and metachronous pulmonary metastasis specimens from 19 patients with high‐grade osteosarcoma. Results were analyzed for differences between primary tumor and pulmonary metastases and for correlations between expression patterns and survival.

RESULTS

Positive staining in lung metastases was noted in 68%, 53%, 32%, and 84% of patients for P‐glycoprotein, ErbB‐2, p53, and Bcl‐2, respectively. These percentages were higher than those observed in primary tumor specimens for all genetic markers evaluated, with a significant difference in the percentage of patients with positive staining for P‐glycoprotein (68% vs. 32%; P = 0.05) and a near‐significant difference in the percentage of patients with positive staining for Bcl‐2 (84% vs. 53%; P = 0.08). Patients with ErbB‐2 expression in the primary tumor were more likely to have multiple metastases and shorter recurrence‐free intervals compared with patients in whom ErbB‐2 expression was not observed, whereas differences in P‐glycoprotein, p53, and Bcl‐2 expression were not related to differences in metastatic pattern. PRS was influenced by p53 expression levels in pulmonary metastases, with patients who had negative staining for p53 having a significantly better PRS rate relative to patients with positive staining for p53 (3‐year PRS rate: p53‐negative, 64%; p53‐positive, 17%; P = 0.008).

CONCLUSIONS

In the current study of patients with high‐grade osteosarcoma, most patients exhibited increased cellular expression of P‐glycoprotein, ErbB‐2, and Bcl‐2 in recurrent pulmonary metastases compared with primary tumor. Further studies aimed at investigating the relation between altered p53 expression in lung metastases and postrecurrence survival are recommended. Cancer 2004. © 2004 American Cancer Society.
Skip metastasis in nonsmall cell lung carcinoma
Authors: Prenzel Klaus L. , Baldus Stephan E. , Mönig Stefan P. , Tack Daniela , Sinning Jan M. , Gutschow Christian A. , Grass Guido , Schneider Paul M. , Dienes Hans P. , Hölscher Arnulf H.
Published: April 2004

BACKGROUND

Skip metastasis to mediastinal lymph nodes is a prognostic factor for patients with nonsmall cell lung carcinoma (NSCLC). Little is known about the biologic behavior of tumors with noncontinuous spread to the mediastinal lymph nodes. In patients with pN2 skip metastases, micrometastases to N1 lymph nodes, which only mimic skip metastases, have not been investigated.

METHODS

In a retrospective study, the authors analyzed the primary tumor specimens from 45 patients with pN2 NSCLC (18 patients had squamous cell carcinomas, 23 had adenocarcinomas, and 4 had large cell carcinomas). They immunohistochemically evaluated the expression of p21, p53, MUC‐1, Bcl‐2, c‐ErbB‐2, and E‐cadherin. Survival rates and biomarker expression levels were compared between patients with pN2 disease and infiltration of N1 lymph nodes (without skip metastasis [n = 28]) and patients with pN2 disease without N1 infiltration (with skip metastasis [n = 17]). To evaluate micrometastasis in the pN1 lymph nodes of 17 patients with skip metastases, lymph nodes were stained using the anticytokeratin antibody, AE1/AE3.

RESULTS

The 5‐year survival rate of patients with skip metastases was 41%, compared with 14% for patients without skip metastases (P = 0.019). In a multivariate analysis, the incidence of skip metastases did not vary significantly according to gender, age, histology, pT status, or cM status. Three skip‐positive patients (17.6%) had micrometastatic tumor involvement of pN1 lymph nodes. After adding these patients to the group of patients without skip metastases, there was still a significant difference in survival between the two groups. p53, MUC‐1, c‐ErbB‐2, and E‐cadherin expression levels in primary tumor specimens were not significantly different in patients with continuous metastasis and patients with skip metastases. Patients with skip metastases expressed lower levels of p21 (P = 0.026), whereas Bcl‐2 expression levels were considerably higher (P = 0.019) compared with the corresponding levels in patients without skip metastases.

CONCLUSIONS

Patients with NSCLC and pN2 skip metastases have a more favorable prognosis than do patients with pN2 disease without skip metastases. Tumor specimens from these patients exhibit elevated expression of the antiapoptosis gene BCL2 and lower expression levels of p21 relative to patients with pN2 disease without skip metastases. Micrometastases occurred in 3 of 17 (17.6%) patients with pN2 disease and skip metastases diagnosed by routine histopathology. Cancer 2004. © 2004 American Cancer Society.
A suitable method for identifying cell aggregates in laser scanning cytometry listmode data for analyzing disaggregated cell suspensions obtained from human cancers
Authors: Shackney Stanley E. , Smith Charles A. , Pollice Agnese A. , Brown Kathryn , Kosiban Deborah
Published: April 2004

Background

The presence of cell aggregates in cell suspensions obtained from human solid tumors can interfere with the measurement of cell DNA content of cell singlets, and can confound multiparameter analysis of other measurements on the same cells. Flow cytometric corrections for cell aggregates based on signal pulse shape have not proven to be reliable. Mathematical models have been developed to correct for cell aggregates in binned DNA histogram data, but they are not suitable for the correction of correlated non‐DNA measurements obtained on the same cells.

Methods

A total of 21 samples representing a variety of normal and malignant human cell types, including normal lymphocytes, normal sputum, human breast cancer cell lines, and mechanically disaggregated cell suspensions from primary breast cancers and nonsmall cell lung cancers, were studied by laser scanning cytometry (LSC) using the CompuCyte laser scanning cytometer (Cambridge, MA). Nuclear area, nuclear perimeter, and an LSC‐based cell texture parameter were measured on ≈400 cells in each sample, using an air‐cooled, violet laser emitting at a wavelength of 405 nm for DAPI excitation, and each cell was classified as a singlet or aggregate by its appearance under direct observation. A “saddle function” provided by CompuCyte was used, together with an algorithm based on the measurements of nuclear area, perimeter, and cell texture (the APT algorithm), to identify cell aggregates and exclude them from the listmode data file.

Results

Proportions of cell aggregates in the uncorrected samples ranging from 6 to 56% (mean, 20%) were reduced to proportions ranging from 0 to 7% (mean, 2.4%) after correction. The discriminant function was “tuned” to maintain both average cell singlet purity and average cell singlet yield at >70% over a broad range of cell DNA contents.

Conclusions

A combined approach to cell aggregate detection, which utilizes both the saddle function and the APT algorithm, produces list mode data files that exclude >80% of cell aggregates from samples of disaggregated cell suspensions of human tumors and other sources of clinical material. Such data files are suitable for multiparameter analysis. © 2004 Wiley‐Liss, Inc.
Reconstruction of chaotic signals with application to channel equalization in chaos‐based communication systems
Authors: Feng Jiuchao , Tse Chi K. , Lau Francis C. M.
Published: April 2004

A number of schemes have been proposed for communication using chaos over the past years. Regardless of the exact modulation method used, the transmitted signal must go through a physical channel which undesirably introduces distortion to the signal and adds noise to it. The problem is particularly serious when coherent‐based demodulation is used because the necessary process of chaos synchronization is difficult to implement in practice. This paper addresses the channel distortion problem and proposes a technique for channel equalization in chaos‐based communication systems. The proposed equalization is realized by a modified recurrent neural network (RNN) incorporating a specific training (equalizing) algorithm. Computer simulations are used to demonstrate the performance of the proposed equalizer in chaos‐based communication systems. The Hénon map and Chua's circuit are used to generate chaotic signals. It is shown that the proposed RNN‐based equalizer outperforms conventional equalizers as well as those based on feedforward neural networks for noisy, distorted linear and non‐linear channels. Copyright © 2004 John Wiley & Sons, Ltd.
Skeletal involvement in patients with diabetes mellitus
Authors: Carnevale Vincenzo , Romagnoli Elisabetta , D'Erasmo Emilio
Published: April 2004

Studies on skeletal involvement in patients with diabetes mellitus have generated conflicting results, largely because of the pathogenetic complexity of the condition.

Several mechanisms may contribute to skeletal damage, including the increased urinary excretion coupled with the lower intestinal absorption of calcium, the inappropriate homeostatic response in terms of parathyroid hormone secretion, and also the complex alteration of vitamin D regulation. Decreased or increased insulin and IGF‐1 concentrations and the effects of the accumulation of glycation endproducts on the bone tissue could also play a role. A possible genetic predisposition is also currently under investigation. Finally, the role of fat tissue in type 1 and type 2 diabetes and that of diabetic complications also deserve note.

As far as bone mass is concerned, in adult patients with type 1 diabetes a moderately reduced bone mineral density has been shown in both axial and appendicular skeleton. On the contrary, patients with type 2 diabetes seem to have higher bone mineral density in respect to healthy control subjects, especially when overweight women are considered.

No clear relationship between bone mass measurements and biochemical parameters of mineral metabolism has been shown in the different types of diabetes.

Cohort studies recently carried out on large samples indicate that diabetic patients (with both type 1 and type 2 disease) have a higher risk for fracture, in particular for hip fracture, the most dangerous osteoporotic complication. This seems to be dependent both on qualitative and quantitative alterations of the bone, as well as on extra‐skeletal factors due to the neuropathic and microangiopathic complications of the disease. Copyright © 2004 John Wiley & Sons, Ltd.
Arbitrary viewpoint image synthesis based on light field construction from uncalibrated image sequence
Authors: Kobayashi Kenkichi , Saito Hideo
Published: April 2004

Recently, image‐based rendering in which the actual image is efficiently utilized to synthesize a new image has been attracting attention. There have been many studies of arbitrary viewpoint image synthesis based on the light field, which is an image‐based rendering procedure. It is now possible to synthesize images with a high degree of realism. However, in the method based on the theory of the light field, the camera parameters used in the imaging must be known (with calibration). In cases such as imaging by a free hand‐held camera, the theory of the light field cannot be applied to the sequence of uncalibrated images. Consequently, this paper proposes an image generation method using the theory of the light field, which can be applied to a sequence of uncalibrated images. In the proposed method, the ray in each frame can be handled appropriately, using only the correspondence between frames, which is derived by tracking the feature points in the uncalibrated image sequence. This is possible because a special space, the projective grid space, which is determined by the two cameras, rather than Euclidean space, that is, ordinary three‐dimensional space, is used for light field construction in the proposed method. In the projective grid space, the general geometrical relations among straight lines and planes in Euclidean space do not apply, but the position of the ray in space can be calculated by using the fundamental matrix. The proposed method is applied to uncalibrated image sequences taken by free hand‐held video cameras. In experiments, the image from an arbitrary viewpoint is generated in a satisfactory way, indicating the usefulness of the proposed method. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(9): 11–21, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20102