bluuebunny/crossref_metadata_2025 huggingface dataset:
Absolute determination of molar masses of standard polystyrenes by means of sedimentation‐diffusion measurements in cyclohexane
Authors: Petrus Vladimír , Porsch Bedr̂ich , Nyström Bo , Sundelöf Lars‐Olof
Published: April 2003

Accurate measurements of the sedimentation coefficients at unit pressure and zero‐concentration s, the diffusion coefficients at zero concentration D0, and the intrinsic viscosities [η] were conducted at theta‐conditions (cyclohexane, 34,5°C) on 11 polystryrene standard samples with narrow molar mass distribution. These samples with nominal mass‐average molar masses (5 · 104 < Mw < 2 · 106 g · mol−1), provided by three manufacturers for the use as calibration standards, were the same as in the previous paper of this series summarizing our measurements in toluene. Logarithmic correlations between s, D0 and [η] are linear with deviations lower than ± 3% and indicate good consistency of all three independent sets of measured quantities. The molar masses MsD as determined from s and D0 by means of the Svedberg equation are in very good accordance with those previously determined in toluene, but for most samples the MsD are lower than the nominal values Mw as given by the manufacturers. For some standards the deviations amount to 15−35% and cannot be explained by experimental errors or by the polydispersity of the samples. On the other hand, two pairs of standards exhibit the same values of s, D0 and [η] in both solvents, although the nominal molar masses differ by 20%. These results lead to the conclusion that the experimentally determined MsD values are more reliable characteristics of the standard samples than the nominal Mw values and that the sedimentation‐diffusion technique is a powerful, though laborious, tool for an absolute determination of the molar mass.
Etude des prépolymères époxydes par chromatographie et 1H NMR à 350 MHz
Authors: Gulino Danièle , Galy Jocelyne , Pascault Jean‐Pierre , Tighzert Lan , Pham Quang Tho
Published: April 2003

The epoxy resins (DGEBA) obtained from 4,4′‐isopropylidendiphenol (bisphenol A) and 1‐chloro‐2,3‐epoxypropane (epichlorohydrin) and synthetized by the “taffy” process were found to consist of oligomers. The composition of prepolymers could be deduced from gel permeation chromatography (GPC), and particularly by high pressure liquid chromatography (HPLC). In the more resolved HPLC spectrum each oligomer was found to be accompanied by satellite peaks. The functionality of the prepolymers, determined by 1H NMR spectroscopy and cryometric or vapour pressure osmometric measurements was found to be less than two. These phenomena are due to the existence of abnormal chain ends having no epoxy group. The structure of the main components spearated by preparative GPC was studied by 1H NMR. For the impurities, the two indentified structures of chain ends are primary and secondary alcohol functions. Finally the compositions of three DGEBA were determined.
Polymères porteurs de dérivés du glycérol, 1. Polymérisation du méthacrylate d'époxy‐2,3 propyle et du méthacrylate‐phényl‐2 butyrate d'hydroxy‐2 triméthylène
Authors: Brosse Jean‐Claude , Mouity‐Moussounda François , Soutif Jean‐Claude
Published: April 2003

Radical polymerizations and copolymerizations of 2,3‐epoxypropyl methacrylate (1) and its reaction product with 2‐phenylbutyric acid (2), 2‐hydroxytrimethylene methacrylate 2‐phenylbutyrate (3), were studied using 2,2′‐azodiisobutyronitrile, benzoyl peroxide, or H2O2 (with UV irradiation) as initiators, and also the influence of the experimental conditions (temperature, concentration, time) on the yield. Due to the reactivity of the oxirane moiety, poly(2,3‐epoxy‐propyl methacrylate) can easily be modified by ring opening reactions, e.g. with carboxylic acids.
Syntheses and characterization of polycondensation products derived from β‐(4‐methoxy‐3‐methyl)phenylglutaconic acid and diols
Authors: Mehta Ashok , Patel Rajni , Dave Harshad , Patel Kanti
Published: April 2003

Five new copolyesters 3a – e were prepared by reacting β‐(4‐methoxy‐3 methyl)phenylglutaconic acid dichloride (1 b) with diols 2 a – e. The polymers were characterized by IR and TG. All polymers were found to decompose in the range of ≈200 to ≈650°C.
Studies of functional diene oligomers with an amino end group, 1. Synthesis of functional oligomers of isoprene with one diisopropylamino end group
Authors: Yoshino Norio , Yamaki Yoshitaka , Nagasaki Yukio , Tsuruta Teiji
Published: April 2003

Lithium diisopropylamide in the presence of diisopropylamine initiates the polymerization of isoprene to form oligomers with one diisopropylamino end group. The molecular weight of the oligomers formed is strongly dependent on the mole ratio diisopropylamine/lithium diisopropylamide. For instance, more than 70% of the oligomers obtained have an average molecular weight of 1 000, provided the reaction is run with an initial mole ratio 1:2 of amine to amide. Reactivities of several allylamine derivatives including the oligomers with amino end groups were studied in regard to their ability as chain transfer agents in the anionic polymerization of isoprene. According to the 1H NMR analysis, these oligomers contain 90% 1,4‐ and 10% 3,4‐enchainments.
Behaviour of poly(N‐vinylcarbazole) in 1,3‐dichlorobenzene/methanol mixtures
Authors: González M. C. , Zamora F. , Guzmán G. M. , León L. M.
Published: April 2003

The behaviour of poly(N‐vinylcarbazole) in a mixture of 1,3‐dichlorobenzene and methanol (solvent/non‐solvent system) is studied. The non‐solvent, methanol, is more strongly adsorbed than 1,3‐dichlorobenzene as judged from changes in the unperturbed dimensions and intrinsic viscosity. Therefore the Mark‐Houwink‐Sakurada constant and the flexibility parameter decrease with increasing methanol contents. A relation between the preferential adsorption parameter and the segment density is given.
Synthesis, characterization and conformational transition in poly(cyclohexylmethyl methacrylate)
Authors: Gargallo Ligia , Mendez Inés , Radic Deodato
Published: April 2003

Poly(cyclohexylmethyl methacrylate), (poly[1‐(cyclohexylmethoxycarbonyl)‐1‐methylethylene]) was prepared and characterized by osmometric and viscometric measurements. The temperature dependences of the viscosity data and of the refractive index increment of the polymer were investigated in isobutyl methyl ketone solution. A discontinuity of the intrinsic viscosity [η] was observed over the temperature range 5°C – 10°C. Also sharp changes of the unperturbed dimensions parameter K⊖ and the thermodynamic parameter B from the Stockmayer‐Fixman plot were observed in the same temperature range. Similar discontinuities occur with the refractive index increments dn/dc. This phenomenon can be accounted for by assuming conformational changes of the chain in the chosen solvent at a specific temperature range. The results are compared with that obtained in poly(cyclohexyl methacrylate). The influence of the spacer group CH2 in the conformational behaviour of poly(cyclohexylmethyl methacrylate) is analyzed.
The cationic polymerisation of 2‐alkenylfurans, 3. Spectroscopic study of the alkylation as important side reaction leading to branched products
Authors: Gandini Alessandro , Martínez Ricardo
Published: April 2003

A spectroscopic (UV, IR, 1H NMR) study of the cationic polymerisation of 2‐vinylfuran (1a) and 2‐isopropenylfuran (2a) showed the existence of an important alkylation reaction at C5 which competes with normal propagation. The extent of this competition depends on the monomer used and the polymerisation temperature. A comparison of the spectra of standard polymers (prepared by radical or stereospecific polymerisation) with those of polymers obtained by cationic initiation allowed to assess the extent of alkylation and its regiospecificity at C5 2‐Methyl‐5‐vinylfuran (1b) and 2‐methyl‐5‐isopropenylfuran (2b) were found to undergo cationic polymerisation without any interference from alkylation reactions. Reactions between these four monomers and 2‐methylfuran in the presence of typical acidic catalysts gave very high yields of alkylated products and no polymerisation, thus confirming the importance of this electrophilic reaction and its possible application to synthetic uses.
Polymerization of lactams, 64. Nonactivated anionic polymerization of 2‐pyrrolidone in the presence of quaternary ammonium cations
Authors: Roda Jan , Králíček Jaroslav , Šubr Vladimír , Stehlíček Jaroslav
Published: April 2003

The effect of addition of quaternary ammonium halides was studied in the nonactivated polymerization of 2‐pyrrolidone (1) initiated with the potassium salt of 2‐pyrrolidone (2‐oxo‐1‐pyrrolidinylpotassium) (2). The polymerization was accelerated upon small additions of Me4NCl, whereas addition of Et4NBr and Bu4NBr rather had a retardation effect and reduced the molecular weight of polymer. The formation of the corresponding quaternary ammonium salts of 2‐pyrrolidone in situ is analogous to the formation of the pure salts in their synthesis from the ammonium halides. The nonactivated polymerization of 1 initiated with the pure tetramethylammonium salt of 2‐pyrrolidone (3) showed all kinetic features of other nonactivated polymerizations of 1. High yields and molecular weights of poly(2‐pyrrolidone) and a higher number of growth centers during polymerization are evidence of a higher dissociation of 3 dissolved in 1 in comparison with 2 as the initiator. The activation energy of polymerization activated with 3 (47,9 kJ · mol−1 in the range 35 to 55°C) and the reaction order with respect to 3 (1,3 at 45°C) were determined.
Orientation of ketones embedded in a polyethylene matrix. Infrared dichroic study
Authors: Schmidt Pavel , Schneider Bohdan
Published: April 2003

Low‐molecular weight ketones embedded in polyethylene films were oriented by cold drawing of the films and the effect of temperature on the orientation was studied by IR dichroism. The loss of orientation of the low‐molecular weight ketones with temperature is discussed on the basis of the Cohen‐Turnbull model of “free volumes”.
Characterization of microgel‐containing polymers by the light scattering method: A new method of evaluation and its comparison with other procedures
Authors: Procházka Ondřej , Tuzar Zdeněk , Kratochvíl Pavel
Published: April 2003

A new method suitable for computer treatment was suggested for the evaluation of data obtained by light scattering from polymer solutions containing microgel. The method is based on the assumption of bimodal molar mass distribution and requires no additional data and/or restrictions. The accuracy of the present method was compared with that of other evaluation procedures (suggested by Lange, Gruber and Schurz, Strazielle, and Kratochvíl) using model mixtures consisting of two polymers differing by 2 to 3 orders of magnitude in molar mass. The values of molecular parameters (Mw,1, Mw, z2, (rz,12)1/2, (rz,22)1/2) obtained by the present method are in general more reliable then those calculated by means of the other evaluation procedures.
Lichtinitiierte polymer‐ und polymerisationsreaktionen, 10. Photoinduzierte zersetzung von diareniodonium‐ und triarensulfoniumsalzen durch kaliumtrisoxalatoferrat
Authors: Baumann Harald , Strehmel Bernd , Timpe Hans‐Joachim , Rehorek Detlef
Published: April 2003

In order to elucidate kinetics and mechanism of photoinitiation processes based on potassium trioxalatoferrate(III) (K3[Fe(cx)3])/ onium compounds/acrylamide (AA) interactions, photolysis and stationary photopolymerization were carried out. Diphenyliodonium chloride (Ph2I⊕Cl⊖) and triphenylsulfonium tetrafluoroborate (Ph3S⊕BF⊖4) were used as onium compounds. These compunds react with photolytically formed ˙CO⊖2 radicals by an electron transfer mechanism. The resulting phenyl radicals were detected by spin trapping with nitrosodurene. The quantum yield of the decomposition of onium salts, ϕIn, depends both on their reduction potentials and concentrations. Thus, an efficient redox reaction between ˙CO⊖2 radical and Ph3S⊕BF⊖4 is impossible because the former reacts faster with the Fe(III) complex. The ratio between rate constants of these competitive reactions (onium compound/Fe(III)) are 0,1 (Ph2I⊕Cl⊖) and 4 · 10−4 (Ph3S⊕BF⊖4). Only with the system K3[Fe(ox)3]/Ph2I⊕Cl⊖/AA a radically induced photopolymerization was observed. Both the rate and the quantum yield (ϕBr) depend on the Ph2I⊕Cl⊖ concentration. A correlation between ϕBr and √ϕIn was found.
Syntheses and chelating properties of polymer‐supported macrocyclic polythioethers
Authors: Tomoi Masao , Abe Osamu , Takasu Nobutaka , Kakiuchi Hiroshi
Published: April 2003

Polymer‐supported macrocyclic polythioethers (7a, b, and 8) were prepared from chloromethylated polystyrene resins (6) and 14‐ or 20‐membered a hydroxyl group containing polythioethers (3a, b, and 5), which were synthesized by the reaction of the corresponding dithiols with 1,3‐dichloro‐2‐propanol (2). The polymer‐supported polythioethers were found to be highly efficient adsorbents of Ag(I), moderately effective for Cu(II), but less effective for Cd(II). For Ag(I) the binding ability of 7a is almost independent of the morphology of the polymer support, whereas for Cu(II) the binding ability depends on the morphology. Adsorbed Ag(I) or Cu(II) were removed by treatment with an ammonia solution from the polymer‐supported macrocyclic polythioethers, which can be re‐used without a significant decrease in binding ability.
Resines époxydes, 1. Mécanisme de polycondensation entre le bis[(époxy‐2,3 propoxy)‐4 phényl]‐2,2 propane et la m‐phénylénediamine par 13C NMR
Authors: Grenier‐Loustalot Marie‐Florence , Grenier Philippe
Published: April 2003

Curing of 2,2‐bis[4‐(2,3‐epoxypropoxy)phenyl]propane (diglycidyl ether of bisphenol A) (1) with m‐phenylenediamine (2) was performed in a variable temperature probe of a 13C FT NMR spectrometer (62,89 MHz). The formation of an initial adduct was directly observed and the progress of polymerisation was followed by recording the 13C NMR spectra at time intervals. Unreacted epoxide carbon atoms were detected in one sample as well as in a sample of 1 cured by a standard procedure.
Poly(ethylene glycol)s grafted onto crosslinked polystyrenes, 2. Multidetachably anchored polymer systems for the synthesis of solubilized peptides
Authors: Hellermann Heidi , Lucas Heinz‐Werner , Maul Jürgen , Pillai V. N. Rajasekharan , Mutter Manfred
Published: April 2003

Poly(ethylene glycol)s grated onto suitably functionalized, crosslinked polystyrenes were introduced as a new class of multidetachably immobilized hydrophilic macromolecular supports for the synthesis of peptides. This new polymeric carrier system facilitates both the homogeneous solvation of the reaction site and the insolubilization of the substrate, which are prerequisites for an efficient multistep synthesis using polymeric supports. In these support systems, a strongly solvated hydrophilic linear chain molecule, poly(ethylene glycol) (PEG)

Systematic IUPAC name: α‐Hydro‐ω‐hydroxypoly(oxyethylene).

, is attached to an insoluble, crosslinked polystyrene through suitable anchoring linkages. At the free chain end of this supported PEG, amino acid residues were stepwise incorporated following the standard synthetic methodology for peptides. A special feature of these new carriers is that the use of an orthogonal set of anchoring linkages to connect the polystyrene, PEG and the peptide provides access to the PEG‐bound solubilized peptide or to the free peptide, as desired. The applications of these new polymeric supports are illustrated by the synthesis of thioredoxin partial sequences in the free and PEG‐bound solubilized forms.
Accuracy of antenatal fetal ultrasound in the diagnosis of duplex kidneys
Authors: Whitten S. M. , McHoney M. , Wilcox D. T. , New S. , Chitty L. S.
Published: April 2003

Objectives

To assess the accuracy of ultrasound diagnosis of duplex kidneys in the fetus and to identify prognostic features of antenatal sonography associated with this diagnosis.

Methods

Retrospective identification of cases with an antenatal diagnosis of duplex kidney was made from computerized databases. Results of postnatal radiological investigations were obtained from the unit where delivery took place.

Results

A total of 75% of cases seen in a multidisciplinary fetal renal clinic were correctly diagnosed as having a duplex kidney. Prognostic sonographic features are described. Detection of two separate poles or a ureterocele were strongly associated with a correct diagnosis. Accuracy was increased when two or more prognostic features were seen.

Conclusion

Accurate sonographic diagnosis of duplex kidneys in the fetus is possible in a dedicated multidisciplinary setting. Antenatal counseling and planning of postnatal care for the infant can be made with a high degree of certainty. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Multivariable analysis of tests for the diagnosis of intrauterine growth restriction
Authors: Bachmann L. M. , Khan K. S. , Ogah J. , Owen P.
Published: April 2003

Objectives

To describe how data from antenatal fetal ultrasound biometry, amniotic fluid index and umbilical artery Doppler can be appropriately combined using multivariable models and to investigate how the addition of these ultrasound parameters influences the ability to predict intrauterine growth restriction (IUGR).

Methods

This was a prospective cohort study involving 274 low‐risk pregnancies undergoing serial ultrasound examination at predetermined intervals. Standard deviation (Z) scores of the last values for fetal abdominal area (FAA), growth velocity of the FAA, amniotic fluid index (AFI) and umbilical artery Doppler pulsatility index prior to delivery were calculated for 260 fetuses. Customized estimated fetal weight (cEFW) centiles were also calculated using the last EFW before delivery after adjustment for fetal gender, gestational age, birth order and maternal weight, height and ethnic origin. Following delivery the neonatal ponderal index was calculated and centile position obtained. A neonatal ponderal index <25th centile served as the main outcome measure for diagnosis of IUGR. Logistic regression analysis was used to delineate the predictive value of the three fetal growth tests FAA, FAA growth velocity and cEFW and the additional values of AFI and pulsatility index of the umbilical artery.

Results

The areas under the receiver–operating characteristics (ROC) curves (95% confidence interval) for FAA, FAA growth velocity and cEFW alone were 0.819 (0.748–0.891), 0.784 (0.699–0.869) and 0.74 (0.643–0.837), respectively, in the prediction of a neonatal ponderal index <25th centile. The addition of both the AFI and pulsatility index to FAA, FAA growth velocity and cEFW generated small increases in the areas, to 0.831 (0.758–0.904), 0.817 (0.735–0.899) and 0.766 (0.672–0.859), respectively. These improvements in diagnostic prediction were not statistically significant.

Conclusions

The addition of AFI and umbilical artery pulsatility index to the fetal biometry parameters did not significantly increase the ROC areas in the study population. The approach applied in this study is useful in the context of hypothesis generation. Further studies using larger data sets and other predictors should be carried out using the analytical techniques outlined in this paper to determine the contribution of various antenatal tests in the prediction of IUGR. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Epignathus: always a simple teratoma? Report of an exceptional case with two additional fetiforme bodies
Authors: Sarioglu N. , Wegner R. D. , Gasiorek‐Wiens A. , Entezami M. , Schmock J. , Hagen A. , Becker R.
Published: April 2003

We report on a case of a fetal epignathus combined with two fetus‐like structures resembling acardius acranius. The anomaly was detected at 23 weeks of gestation and led to termination of pregnancy at 24 weeks. This is the first description of epignathus with parasitic fetuses detected prenatally. It shows that the boundary between fetal teratoma and multiple pregnancy in special cases may be difficult to define. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal diagnosis of total anomalous pulmonary venous connection to the portal vein associated with right atrial isomerism
Authors: Boopathy Vijayaraghavan S. , Rao A. R. , Padmashree G. , Raman M. L.
Published: April 2003

We report the prenatal diagnosis of total anomalous pulmonary venous connection to the portal system in a 20‐week fetus with right atrial isomerism. The apex of the fetal heart pointed to the left, the fetal stomach was on the right, there was a common atrioventricular valve, the left ventricle was small and the abdominal aorta and inferior vena cava were on the left side; all these features were suggestive of right atrial isomerism. An anomalous vein was connected to the portal vein which ascended above the diaphragm and ended in a confluence of pulmonary veins, posterior to the common atrium. Color Doppler imaging helped confirm the diagnosis of total anomalous pulmonary venous connection. The prenatal findings were confirmed on autopsy. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Conducting nanowires built by controlled self-assembly of amyloid fibers and selective metal deposition
Authors: Scheibel Thomas , Parthasarathy Raghuveer , Sawicki George , Lin Xiao-Min , Jaeger Heinrich , Lindquist Susan L.
Published: April 2003

Recent research in the field of nanometer-scale electronics has focused on the operating principles of small-scale devices and schemes to realize useful circuits. In contrast to established “top-down” fabrication techniques, molecular self-assembly is emerging as a “bottom-up” approach for fabricating nanostructured materials. Biological macromolecules, especially proteins, provide many valuable properties, but poor physical stability and poor electrical characteristics have prevented their direct use in electrical circuits. Here we describe the use of self-assembling amyloid protein fibers to construct nanowire elements. Self-assembly of a prion determinant from
Saccharomyces cerevisiae
, the N-terminal and middle region (NM) of Sup35p, produced 10-nm-wide protein fibers that were stable under a wide variety of harsh physical conditions. Their lengths could be roughly controlled by assembly conditions in the range of 60 nm to several hundred micrometers. A genetically modified NM variant that presents reactive, surface-accessible cysteine residues was used to covalently link NM fibers to colloidal gold particles. These fibers were placed across gold electrodes, and additional metal was deposited by highly specific chemical enhancement of the colloidal gold by reductive deposition of metallic silver and gold from salts. The resulting silver and gold wires were ≈100 nm wide. These biotemplated metal wires demonstrated the conductive properties of a solid metal wire, such as low resistance and ohmic behavior. With such materials it should be possible to harness the extraordinary diversity and specificity of protein functions to nanoscale electrical circuitry.
The melanocortin-1 receptor gene mediates female-specific mechanisms of analgesia in mice and humans
Authors: Mogil Jeffrey S. , Wilson Sonya G. , Chesler Elissa J. , Rankin Andrew L. , Nemmani Kumar V. S. , Lariviere William R. , Groce M. Kristina , Wallace Margaret R. , Kaplan Lee , Staud Roland , Ness Timothy J. , Glover Toni L. , Stankova Magda , Mayorov Alexander , Hruby Victor J. , Grisel Judith E. , Fillingim Roger B.
Published: April 2003

Sex specificity of neural mechanisms modulating nociceptive information has been demonstrated in rodents, and these qualitative sex differences appear to be relevant to analgesia from κ-opioid receptor agonists, a drug class reported to be clinically effective only in women. Via quantitative trait locus mapping followed by a candidate gene strategy using both mutant mice and pharmacological tools, we now demonstrate that the melanocortin-1 receptor (
Mc1r
) gene mediates κ-opioid analgesia in female mice only. This finding suggested that individuals with variants of the human
MC1R
gene, associated in our species with red hair and fair skin, might also display altered κ-opioid analgesia. We found that women with two variant
MC1R
alleles displayed significantly greater analgesia from the κ-opioid, pentazocine, than all other groups. This study demonstrates an unexpected role for the
MC1R
gene, verifies that pain modulation in the two sexes involves neurochemically distinct substrates, and represents an example of a direct translation of a pharmacogenetic finding from mouse to human.
The hydration structure of guanidinium and thiocyanate ions: Implications for protein stability in aqueous solution
Authors: Mason P. E. , Neilson G. W. , Dempsey C. E. , Barnes A. C. , Cruickshank J. M.
Published: April 2003

Neutron diffraction experiments were carried out on aqueous solutions containing either guanidinium or thiocyanate ions. The first-order difference method of neutron diffraction and isotopic substitution was applied, and the hydration structures of two of nature's strongest denaturant ions were determined. Each ion is shown to interact weakly with water: Guanidinium has no recognizable hydration shell and is one of the most weakly hydrated cations yet characterized. Hydration of thiocyanate is characterized by a low coordination number involving around one hydrogen-bonded water molecule and approximately two water molecules weakly interacting through “hydration bonds.” The weak hydration of these denaturant ions strongly supports suggestions that a major contribution to the denaturant effect is the preferential interaction of the denaturant with the protein surface. By contrast, solute species such as many sugars and related polyols that stabilize proteins are strongly hydrated and are thus preferentially retained in the bulk solvent and excluded from the protein surface.
Treatment with isotretinoin inhibits lipofuscin accumulation in a mouse model of recessive Stargardt's macular degeneration
Authors: Radu Roxana A. , Mata Nathan L. , Nusinowitz Steven , Liu Xinran , Sieving Paul A. , Travis Gabriel H.
Published: April 2003

Recessive Stargardt's macular degeneration is an inherited blinding disease of children caused by mutations in the
ABCR
gene. The primary pathologic defect in Stargardt's disease is accumulation of toxic lipofuscin pigments such as
N
-retinylidene-
N
-retinylethanolamine (A2E) in cells of the retinal pigment epithelium. This accumulation appears to be responsible for the photoreceptor death and severe visual loss in Stargardt's patients. Here, we tested a therapeutic strategy to inhibit lipofuscin accumulation in a mouse model of recessive Stargardt's disease. Isotretinoin (Accutane) has been shown to slow the synthesis of 11-
cis
-retinaldehyde and regeneration of rhodopsin by inhibiting 11-
cis
-retinol dehydrogenase in the visual cycle. Light activation of rhodopsin results in its release of
all-trans
-retinaldehyde, which constitutes the first reactant in A2E biosynthesis. Accordingly, we tested the effects of isotretinoin on lipofuscin accumulation in

abcr
−/−

knockout mice. Isotretinoin blocked the formation of A2E biochemically and the accumulation of lipofuscin pigments by electron microscopy. We observed no significant visual loss in treated

abcr
−/−

mice by electroretinography. Isotretinoin also blocked the slower, age-dependent accumulation of lipofuscin in wild-type mice. These results corroborate the proposed mechanism of A2E biogenesis. Further, they suggest that treatment with isotretinoin may inhibit lipofuscin accumulation and thus delay the onset of visual loss in Stargardt's patients. Finally, the results suggest that isotretinoin may be an effective treatment for other forms of retinal or macular degeneration associated with lipofuscin accumulation.
C-terminal-binding protein corepresses epithelial and proapoptotic gene expression programs
Authors: Grooteclaes Madeleine , Deveraux Quinn , Hildebrand Jeffrey , Zhang Qinghong , Goodman Richard H. , Frisch Steven M.
Published: April 2003

The genesis of carcinoma cells often involves epithelial-to-mesenchymal transitions and the acquisition of apoptosis resistance, but it is unclear whether these alterations are controlled coordinately or independently. Our previously reported effects of adenovirus E1a in human tumor cells raised the possibility that the E1a-interacting corepressor protein C-terminal-binding protein (CtBP) might selectively repress epithelial cell adhesion and proapoptotic genes. Here, we report that CtBP-knockout cells were hypersensitive to apoptosis. Correspondingly, microarray analysis of CtBP-knockout vs. CtBP-rescued mouse embryo fibroblasts revealed that many epithelial-specific and proapoptotic genes were indeed regulated by CtBP. Neither the apoptosis nor the repression activities of CtBP required histidine-315, suggesting that the proposed dehydrogenase activity is not essential for CtBP function. The results presented herein establish two functional roles of CtBP: to corepress epithelial genes, thus permitting epithelial-to-mesenchymal transitions, and to modulate the cellular threshold for apoptotic responses.
Comprehensive sampling of gene expression in human cell lines with massively parallel signature sequencing
Authors: Jongeneel C. Victor , Iseli Christian , Stevenson Brian J. , Riggins Gregory J. , Lal Anita , Mackay Alan , Harris Robert A. , O'Hare Michael J. , Neville A. Munro , Simpson Andrew J. G. , Strausberg Robert L.
Published: April 2003

Whereas information is rapidly accumulating about the structure and position of genes encoded in the human genome, less is known about the complexity and relative abundance of their expression in individual human cells and tissues. Here, we describe the characteristics of the transcriptomes of two cultured cell lines, HB4a (normal breast epithelium) and HCT-116 (colon adenocarcinoma), using massively parallel signature sequencing (MPSS). We generated in excess of 10
7
short signature sequences per cell line, thus providing a comprehensive snapshot of gene expression, within the technical limitations of the method. The number of genes expressed at one copy per cell or more in either of the lines was estimated to be between 10,000 and 15,000. The vast majority of the transcripts found in these cells can be mapped to known genes and their polyadenylation variants. Among the genes that could be identified from their signature sequences, ≈8,500 were expressed by both cell lines, whereas 6,000 showed cellular specificity. Taking into account sequence tags that map uniquely to the genome but not to known transcripts, overall the data are consistent with an upper limit of 17,000 for the total number of genes expressed at more than one copy per cell in one or both of the two cell lines examined.
Probing polymerization forces by using actin-propelled lipid vesicles
Authors: Upadhyaya Arpita , Chabot Jeffrey R. , Andreeva Albina , Samadani Azadeh , van Oudenaarden Alexander
Published: April 2003

Actin polymerization provides a powerful propulsion force for numerous types of cell motility. Although tremendous progress has been made in identifying the biochemical components necessary for actin-based motility, the precise biophysical mechanisms of force generation remain unclear. To probe the polymerization forces quantitatively, we introduce an experimental system in which lipid vesicles coated with the
Listeria monocytogenes
virulence factor ActA are propelled by actin polymerization. The polymerization forces cause significant deformations of the vesicle. We have used these deformations to obtain a spatially resolved measure of the forces exerted on the membrane using a model based on the competition between osmotic pressure and membrane stretching. Our results indicate that actin exerts retractile or propulsive forces depending on the local membrane curvature and that the membrane is strongly bound to the actin gel. These results are consistent with the observed dynamics. After a slow elongation of the vesicle from a spherical shape, the strong bonds between the actin gel and the membrane rupture if the retractile forces exceed a critical value, leading to a rapid release of the vesicle's trailing edge.
Robotics and assembly automation at TEAM
Authors: Rooks Brian
Published: April 2003

Ten events made up the new total engineering and manufacturing (TEAM) exhibition, one of which, factory automation (FA) is the focus of this article. A main sponsor of FA was Bosch Rexroth, and a report is given on the state of the company since the acquisition of Rexroth by Bosch. Descriptions are given of a new range of Rexroth Bosch articulated arm robots and an application of the company's Turboscara robots assembling lambda exhaust control probes. Other exhibitors featured are ABB with a new heavy duty robot, Orwin Automation who demonstrated an automatic bagger, part of its flexible intelligent packaging systems (FIPS) range and DT Assembly and Test who promoted its project and value engineering expertise. Finally, reference is made to GE Panametrics hand held ultrasonic weld testing system.
The automated filling of bonded joints – Part 2 three dimensional joints
Authors: Young Ken , Pearson Ian
Published: April 2003

Building automobile bodies from lightweight materials using space‐frame construction techniques is increasingly popular because of exhaust emission legislation. One proposed method of achieving this is by using plug and socket joints, which are injected with adhesive after assembly. A method for controlling this process, irrespective of component tolerances, is proposed here. A test rig representing a plug and socket joint was injected with the adhesive and a method for successfully filling the butt‐jointed end of the joint found. The addition of a restriction to the joint's open end gave a method of filling the cavity without creating any air gaps. The use of neoprene O‐ring seals for creating the restriction was investigated. The pressure of the adhesive at the joint inlet (gate) was recorded (data logger), and an analysis of this has been used to determine the point when adhesive injection can be arrested and the joint correctly filled.
Management of irritable bowel syndrome
Authors: Gunn M C , Cavin A A , Mansfield J C
Published: April 2003

The diagnosis of irritable bowel syndrome (IBS) is made on clinical grounds with appropriate limited investigations to exclude organic disease. IBS is common and may have a significant impact on a patient’s quality of life. Psychological symptoms are common. IBS may benefit from pharmacological and non-pharmacological management. Specific measures should be directed towards the dominant symptoms of constipation or diarrhoea. Several new drugs are currently under evaluation and may prove valuable for subgroups of patients with IBS. Successful management requires a combination of reassurance and explanation about the natural history of the condition.
RECENT TESTS FOR THE STATISTICAL PARTON DISTRIBUTIONS
Authors: BOURRELY CLAUDE , SOFFER JACQUES , BUCCELLA FRANCO
Published: April 2003

We compare some recent experimental results obtained at DESY, SLAC and Jefferson Lab., with the predictions of the statistical model, we have previously proposed. The result of this comparison is very satisfactory.
Dorsal Cortex Lesions Impair Habituation in Turtles (Chrysemys picta)
Authors: Moran Alberto , Wojcik Larissa , Cangiane Lorraine , Schade Powers Alice
Published: April 2003

Two experiments investigated habituation in painted turtles (Chrysemys picta). In the first, turtles were given lesions of the dorsal cortex or sham lesions and then trained on a restraint. Although the sham-lesioned turtles learned to tolerate the restraint, the lesioned animals continued to struggle against it. Thus dorsal cortex lesions disrupted habituation to restraint. In order to test habituation to a looming stimulus in a second experiment, all animals were habituated to the restraint before surgery. Postoperatively they continued to be habituated to the restraint. The looming stimulus was a circular shadow that enlarged suddenly on a screen in front of the turtle. It was presented 5 times per day for 15 days. Between-day or long-term habituation was impaired by dorsal cortex lesions.
Afferent and Efferent Connections of Nucleus praeeminentialis in the Channel Catfish: A Reevaluation
Authors: New John , He Jie
Published: April 2003

Nucleus praeeminentialis (nPr) is an isthmic nucleus that has been described in the brains of electrosensory teleost fishes and a single non-electrosensory species. The nucleus receives axon collaterals of ascending medullary sensory lemniscal neurons. Axons of nPr neurons project in turn back down onto those same populations of medullary projection neurons via a descending parallel fiber system (the molecular layer or cerebellar crest). Thus nPr forms a link in a sensory feedback loop that modulates the activity of neurons that relay information from medulla to midbrain. The purpose of this study is to investigate the nature of the afferent and efferent connections of the nPr with the specific aim of investigating other sources of input into this modulatory circuit. Transport of neuronal tracers (horseradish peroxidase, DiI and dextran amines) revealed that nPr has extensive interconnections with nuclei in the basal metencephalon, cerebellum, octavolateralis column and basal medulla. A previously described source of afference, the torus semicircularis in the mesencephalon, was not indicated by our studies. Our studies suggest that in addition to regulating the sensitivity and resolution of electrosensory and mechanosensory lateral line systems, the nPr may play a role in the resolution of signal ambiguities posed by auditory or vestibular stimulation of the saccular endorgan of the inner ear.
Role of the Archistriatal Nucleus taeniae in the Sexual Behavior of Male Japanese Quail (Coturnix japonica): A Comparison of Function with the Medial Nucleus of the Amygdala in Mammals
Authors: Thompson Richmond , Goodson James , Ruscio Michael , Adkins-Regan Elizabeth
Published: April 2003

Nucleus taeniae (Tn) is a prominent cell group within the medial archistriatum of birds. Based upon similarities in sex-steroid binding sites, this nucleus has been hypothesized to be homologous to the medial nucleus of the amygdala (Me) in mammals, which is known to modulate the expression of sexual behavior in rodents. We therefore tested whether or not Tn likewise plays a role in the expression of sexual behavior in male Japanese quail. We found that bilateral damage to Tn produced deficits in several components of male responses toward female stimuli that were indicative of decreased sexual arousal, incuding goal-oriented responses, vocalizations associated with courtship, and motor reflexes that precede copulation. Our results suggest that Tn influences a wide range of behavioral functions in response to sexual stimuli, and they indicate a function for this nucleus similar to that subserved by the Me in mammals. These results strengthen the argument that these sex-steroid accumulating cell groups are homologous and suggest a conservation of function for them despite the vastly divergent evolutionary histories separating birds and mammals.
The Foam Production System of the Male Japanese Quail: Characterization of Structure and Function
Authors: Seiwert C.M. , Adkins-Regan E.
Published: April 2003

The research described here characterizes a unique neuromuscular system involved in reproductive behavior – the foam production system of the male Japanese quail (Coturnix japonica). Male quail produce a large amount of foam that is transferred to the female during copulation, enhancing male fertilization success. The source is the foam gland complex, a large sexually dimorphic, androgen sensitive, external protuberance of the dorsal cloaca, consisting of glandular units interdigitated with striated muscle fibers of the sphincter cloacae muscle (mSC). Electromyographic (EMG) analysis of mSC activity in freely moving males interacting with females revealed different characteristics of the EMG signal during copulation, voiding of excreta, and other mSC movement. The amount of mSC activity and also the amount of foam produced were greatly increased by the presence of a female behind a screen. Denervation of mSC eliminated normal mSC movement and also abolished foam production, confirming that mSC activity is the mechanism for foam production. The spinal cord locations of the motoneurons innervating the major cloacal muscles, including mSC, were determined by injecting cholera-toxin conjugated horseradish peroxidase into each muscle. Labelled somata with multiple primary dendrites were located in Area IX of the lateral motor column of synsacral segments 7, 8, or 9 or 8, 9, and 10. The motoneurons serving mSC were intermingled with those projecting to the other cloacal muscles, but there were differences in the rostral-caudal placement of these neural populations. Thus mSC activity is an integral part of the male’s reproductive behavior, mSC activity can be socially stimulated, and mSC activity occurring in anticipation of copulation is likely to be functionally significant. Continued investigation of this highly accessible system has the potential to shed light on the mechanisms by which complex motor acts are produced and hormonally regulated.
Developmental Homologues: Lineages and Analysis
Authors: Trevarrow Bill
Published: April 2003

Developmental processes present several problems for identifying homologies and analyzing their evolution. Most evolutionary techniques approach homologies from either a taxonomic or a molecular perspective. Approaches that can accommodate many problems of developmental evolution are not well developed. Developmental process and evolutionary lineage complexity lead to a number of largely unappreciated conceptual and analytic problems. Developmental processes can evolve by duplication or diversification. Each process is in a hierarchy of super- and subprocesses. As they evolve, process components may be exchanged with or acquired by those of other processes. Because they do not fit into standard analytic procedures, these situations (including reticulate or reticulate-appearing lineages, partial homologues, iterative features, and the tracing of nontaxonomic and nonmolecular evolutionary lineages) are often ignored or considered illegitimate. Biology’s disdain for the dichotomously branching phylogenetic lineages that are the basis of standard analytic approaches is ignored at the risk of making falsely negative homology evaluations. I will present an approach that can accommodate analyses of these situations. The use of nontaxonomic and nonmolecular lineages provides a way to structure comparisons between other entities, as taxonomic lineages structure comparisons among potential homologues. From an informational point of view, any entity (either a structure or process) with an evolutionary history is a potential homologue with a potential evolutionary lineage. Comparing lineages of interacting entities can reveal topological incongruences among them. Methods that identify reticulated taxonomic and molecular lineages should also apply to other lineages. Partial homologues, resulting from reticulated lineages, can be handled in several possible ways. Analytically, such an entity can be treated as a partial homologue, a novel feature, an independent sub-unit, or a unitary feature homologous to the major contributor of its inherited features.
Rattlesnake Hunting Behavior: Correlations between Plasticity of Predatory Performance and Neuroanatomy
Authors: Kardong Kenneth V. , Berkhoudt Herman
Published: April 2003

Rattlesnakes may shift between visual (eyes) and infrared (facial pits) stimuli without significant loss of predatory performance during an envenomating strike. The relative equivalency of these proximate stimuli is correlated with the organization of the associated neural pathways in the central nervous system. Visual and infrared information, although gathered by different sensory organs, converges within the optic tectum in an orderly spatiotopical representation where bimodal neurons respond to both stimuli. In turn, the tectum sends efferent pathways directly to premotor areas (brainstem) and indirectly to motor areas (spinal cord) where axial muscles involved in the strike might be activated. On the other hand, rattlesnakes do not maintain a high level of equivalent predatory performance when switching between chemosensory stimuli i.e., olfactory, and vomeronasal information. Deprived of vomeronasal input, strikes drop by about half, and poststrike trailing is lost entirely. Surprisingly, compensation by switching to information delivered via an intact olfactory input does not occur, despite the convergence of chemosensory information within the central nervous system. Finally, the launch of a targeted, envenomating strike involves both these modalities: radiation reception (visual, infrared) and chemoreception (olfactory, vomeronasal). However, in the absence of chemosensory information, the radiation modalities do not completely compensate, nor does the animal maintain a high level of predatory performance. Similarly, in the absence of radiation information, the chemosensory modalities do not completely compensate, nor does the animal maintain a high level of predatory performance. The absence of compensation in this multimodal system is also correlated with an absence of convergence of radiation and chemical information, at least at the level of first and second-order neurons, in the central nervous system.
Comparative Anatomy of the Claustrum in Selected Species: A Morphometric Analysis
Authors: Kowiański Przemysław , Dziewiątkowski Jerzy , Kowiańska Jolanta , Moryś Janusz
Published: April 2003

The morphology of the claustrum was studied by stereological methods in representatives of five mammalian orders (Insectivora, Rodentia, Lagomorpha, Carnivora and Primates). In each species under study, a dorsal and a ventral part of the nucleus can be distinguished. Based on differences in shape and separation from surrounding structures, five morphological types of the claustrum occur. The claustrum of Insectivora and some rodents represents the least complicated morphological type. The nucleus is very poorly separated from the surrounding structures. The human claustrum is morphologically the most complicated, although the two above-mentioned principal divisions are apparent. The ventrally situated paraamygdalar part of the human claustrum may correspond to the endopiriform nucleus or ventral part of the claustrum of other mammals, because of its morphological characteristics and connections with the limbic system. In guinea pigs, traditionally classified as members of the Rodentia, a characteristic morphological type of the claustrum is present. This observation may support arguments questioning the current position of this species in mammalian classification. Based on stereological studies, the increase of the claustral volume that occurs with increase of the hemispheric volume is significantly smaller than the increase of the isocortical volume and larger than the increase of the allocortical volume. The increase of the volume of the dorsal and ventral parts of the claustrum does not differ significantly in the species under study. Neurons of the claustrum represent differentiated morphology. The numerical density of neurons in the dorsal part of the claustrum is significantly higher than in the ventral one. Differences in the morphology and cellular structure of the two parts of the claustrum may suggest differences in function of the two parts of the nucleus, most probably concerned with transfer of information among various cortical regions. Changes in the claustrum, a cortico-related structure, that occur with increased brain volume, may suggest that its development is less dynamic than that of the isocortex.