bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of hepatic oxidative DNA damage in patients with hepatoblastoma and children with non‐neoplastic disease
Authors: Ikeda Hitoshi , Hirato Junko , Suzuki Norio , Kuroiwa Minoru , Maruyama Kenichi , Tsuchida Yoshiaki
Published: October 2004

Background

The authors have revealed a significant association between hepatoblastoma and low birth weight. This study was done to explore the evidence that liver cells were oxidatively damaged, based on the hypothesis that oxidative damage to DNA is involved in the development of hepatoblastoma in children of low birth weight.

Procedure

Oxidative DNA damage in the liver was examined by immunohistochemically detecting the presence of a DNA repair product, 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG), in five patients with hepatoblastoma and 14 children with non‐neoplastic disease.

Results

Positive staining for 8‐OHdG was observed in all five patients with hepatoblastoma. Distribution of 8‐OHdG positivity was diffuse in the intralobular area in one patient and was restricted to the periportal area of the lobules in four patients. There was no apparent correlation between birth weight of the patients, histological findings in the liver, and the distribution of 8‐OHdG positivity. In children with non‐neoplastic disease, 8‐OHdG was detected in nine of 14 patients, and 8‐OHdG was positive in the intralobular area of the liver parenchyma except in one patient.

Conclusions

These results suggest that the cause of oxidative DNA damage in patients with hepatoblastoma may be different from the cause, extensive parenchymal damage to the liver, in children with non‐neoplastic disease, but the 8‐OHdG formation is not specific to hepatoblastoma patients of low birth weight. Further studies to elucidate the true reason for the high incidence of hepatoblastoma in children of low birth weight are necessary. Med Pediatr Oncol 2001; 37:505–510. © 2001 Wiley‐Liss, Inc.
An intramolecular ionic hydrogen bond stabilizes a cis amide bond rotamer of a ring‐opened rapamycin‐degradation product
Authors: Zhou Casey Chun , Stewart Kent D. , Dhaon Madhup K.
Published: October 2004

Rapamycin (1), a macrolide immunosuppressant, undergoes degradation into ring‐opened acid products 2 and 3 under physiologically relevant conditions. The unsaturated product (3) was isolated and studied in this work. Unlike 1, which has its amide primarily in a trans conformation in solution, 3 has both cis and trans conformations in approximately a 1:1 ratio in dimethyl sulfoxide (DMSO). The amount of cis rotamer was increased dramatically in the presence of an organic base such as triethylamine. The detailed NMR results indicate that the cis rotamer is stabilized through an intramolecular ionic hydrogen bond of the carboxylate anion with the tertiary alcohol as part of a nine‐membered ring system. This hydrogen bond was characterized further in organic media and the trans–cis rotamer equilibria were used to estimate the relative bond strengths in several solvents. The additional stabilization arising from this ionic hydrogen bond in the cis rotamer was determined to be 1.4 kcal mol−1 in DMSO‐d6, 2.0 kcal mol−1 in CD3CN and 1.1 kcal mol−1 in CD3OD. Copyright © 2004 John Wiley & Sons, Ltd.
Role of motor unit structure in defining function
Authors: Monti Ryan J. , Roy Roland R. , Edgerton V. Reggie
Published: October 2004

Motor units, defined as a motoneuron and all of its associated muscle fibers, are the basic functional units of skeletal muscle. Their activity represents the final output of the central nervous system, and their role in motor control has been widely studied. However, there has been relatively little work focused on the mechanical significance of recruiting variable numbers of motor units during different motor tasks. This review focuses on factors ranging from molecular to macroanatomical components that influence the mechanical output of a motor unit in the context of the whole muscle. These factors range from the mechanical properties of different muscle fiber types to the unique morphology of the muscle fibers constituting a motor unit of a given type and to the arrangement of those motor unit fibers in three dimensions within the muscle. We suggest that as a result of the integration of multiple levels of structural and physiological levels of organization, unique mechanical properties of motor units are likely to emerge. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 848–866, 2001
Myostatin, insulin‐like growth factor‐1, and leukemia inhibitory factor mRNAs are upregulated in chronic human disuse muscle atrophy
Authors: Reardon Katrina A. , Davis Jonathon , Kapsa Robert M.I. , Choong Peter , Byrne Edward
Published: October 2004

Human disuse muscle atrophy frequently accompanies orthopedic injury, arthritis, or bed rest, and recovery is often incomplete despite current rehabilitation programs. We have studied the vastus lateralis muscle in 12 patients with chronic disuse atrophy associated with chronic osteoarthritis of the hip both preoperatively and after total hip arthroplasty. Semiquantitative reverse transcriptase–polymerase chain reaction (RT‐PCR) demonstrated an increase in the level of expression of myostatin, insulin‐like growth factor‐1 (IGF‐1) and leukemia inhibitory factor (LIF) mRNAs compared to healthy control muscle. In all patients there was a significant correlation preoperatively between increasing myostatin mRNA expression and reduction in type 2A and 2B fiber area. In the 8 female patients there was a significant correlation between increased myostatin mRNA expression and the atrophy factor calculated for 2A and 2B fiber types preoperatively. We hypothesize that a complex interaction occurs between muscle growth regulating factors in the genesis of muscle wasting. Our results indicate that myostatin is a muscle‐wasting factor contributing to type 2B and 2A atrophy. Other muscle growth factors, such as IGF‐1 and LIF, may be upregulated in a counterregulatory fashion or may be involved in the fiber type switching seen in disuse muscle wasting. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 893–899, 2001
Effects of FK506 on nerve regeneration and reinnervation after graft or tube repair of long nerve gaps
Authors: Navarro Xavier , Udina Esther , Ceballos Dolores , Gold Bruce G.
Published: October 2004

We compared the effects of FK506 administration on regeneration and reinnervation after sciatic nerve resection and repair with an autologous graft or with a silicone tube leaving a 6‐mm gap in the mouse. Functional reinnervation was assessed by noninvasive methods to determine recovery of motor, sensory, and sweating functions in the hindpaw over 4 months after operation. Morphometric analysis of the regenerated nerves was performed at the end of follow‐up. The nerve graft allowed for faster and higher levels of reinnervation in the four functions tested than silicone tube repair. Treatment with FK506 (for the first 9 weeks only) resulted in a slight, although not significant, improvement of the onset of reinnervation and of the maximal degree of recovery achieved after autografting. The recovery of pain sensibility and of the compound nerve action potentials in the digital nerves, which directly depend on axonal regeneration, showed better progression with FK506 than reinnervation of muscles and sweat glands, which require reestablishment of synaptic contacts with target cells. The myelinated fibers in the regenerated nerve showed a more mature appearance in the FK506‐treated rats. However, FK506 showed a marginal effect in situations in which regeneration was limited, as in a silicone tube bridging a 6‐mm gap in the mouse sciatic nerve. In conclusion, treatment with FK506 improved the rate of functional recovery after nerve resection and autograft repair. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 905–915, 2001
Comparison of interpolation and central activation ratios as measures of muscle inactivation
Authors: Behm David , Power Kevin , Drinkwater Eric
Published: October 2004

The objective of this study was to investigate different methods of estimating muscle inactivation, derived from single and multiple voluntary contractions. Ten subjects performed maximal and submaximal leg extensor contractions to determine an interpolation (IT) or central activation ratio (CAR). A superimposed evoked force was compared with the force output of either a voluntary (CAR) or resting evoked contraction (IT ratio), or the ratios were inserted into regression equations (linear, polynomial, exponential). Linear‐regression estimates of CAR using doublets and tetanus provided physiologically inaccurate values. Whereas IT ratios using doublets (IT‐doublet) and tetanus (IT‐tetanus) had a significant difference in only one interaction, IT‐tetanus and CAR using a tetanus (CAR‐tetanus) estimates provided the most extensive correlation within and between measures. Thus, tetanic stimulation superimposed upon single maximal or multiple contractions seems to provide the most valid measure of muscle inactivation when using the interpolated‐twitch technique. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 925–934, 2001
Do nerve conduction studies predict the outcome of carpal tunnel decompression?
Authors: Bland Jeremy D.P.
Published: October 2004

Patients (n = 3336) who had been tested for suspected carpal tunnel syndrome (CTS) were contacted by postal questionnaire and their opinions sought of the overall subjective outcome of any treatments using a five‐point rating scale. Operative results were compared with preoperative nerve conduction, clinical and demographic variables, and a multiple logistic regression analysis used to identify significant prognostic factors. Among 1268 surgical procedures that were identified, the overall surgical success rate was 69%. Preoperative nerve conduction study findings, greater age, lower symptom scores, longer disease duration, and male gender were significant predictors of poor outcome. Nerve conduction studies had the strongest effect, with patients with middle‐grade abnormalities having better results than those with either very severe or no abnormality. Surgical carpal tunnel decompression has a significant failure rate. The preoperative nerve conduction studies account for a proportion of the total variation in outcome. © 2001 John Wiley & Sons, Inc. Mucle Nerve 24: 935–940, 2001
Spontaneous motor unit behavior in human thenar muscles after spinal cord injury
Authors: Zijdewind Inge , Thomas Christine K.
Published: October 2004

Our first aim was to characterize spontaneous motor unit activity in thenar muscles influenced by chronic cervical spinal cord injury. Thenar surface electromyography (EMG), intramuscular EMG, and abduction and flexion forces were recorded. Subjects were instructed to relax for 2 min. Units still firing after 10 s were considered spontaneously active. Two distinct patterns of spontaneous unit activity were recorded. Units either fired tonically at a mean frequency of 6.1 HZ or were active sporadically (2.2 HZ). Stimuli (e.g., light touch of nearby skin) were then used to influence tonic spontaneous unit activity. Most stimuli produced a change in firing frequency, usually a temporary increase, but sometimes unit frequency decreased or new activity was initiated. Inputs to these motoneurons clearly make important contributions to changes in unit activity. However, the difficulty that subjects had in stopping unit activity, and the initiation of activity when subjects relaxed, suggest that the source of spontaneity may be the motoneuron itself. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 952–962, 2001
Adynamic ileus in severe Guillain–Barré syndrome
Authors: Burns Ted M. , Lawn Nicholas D. , Low Philip A. , Camilleri Michael , Wijdicks Eelco F.M.
Published: October 2004

Adynamic ileus occurred in 17 of 114 patients (15%) with severe Guillain–Barré syndrome (GBS). Cardiovascular dysautonomia coincided with ileus in only five patients. In four patients, mechanical ventilation and immobilization could be implicated; and in eight patients, preexisting conditions such as prior abdominal surgery or incremental doses of opioids could be linked to ileus. Medical management was successful in all patients. Patients with GBS infrequently develop ileus as a manifestation of dysautonomia. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 963–965, 2001
Balanced network flows. V. Cycle‐canceling algorithms
Authors: Fremuth‐Paeger Christian , Jungnickel Dieter
Published: October 2004

We discuss Anstee's approach for solving generalized matching problems by solving an ordinary flow problem on a balanced network first. We give a description of the algorithm which applies not only to matching problems, but also to the general setting. © 2001 John Wiley & Sons, Inc.
Heterogeneity of cycling glial progenitors in the adult mammalian cortex and white matter
Authors: Gensert JoAnn M. , Goldman James E.
Published: October 2004

The heterogeneity and differentiation potential of mitotically active cells in the adult brain were studied by labeling adult rats with BrdU, and isolating an enriched population of cycling cells from neocortex and from subcortical white matter. The majority of this population isolated from either brain region labeled with O4, an early oligodendrocyte marker. In tissue culture, these O4+ progenitors acquired galactocerebroside, a glycolipid of mature oligodendrocytes, but not GFAP, an intermediate filament of astrocytes. A minority population expressed the intermediate filament protein, vimentin, but not O4. This population expressed GFAP after several days in culture. A third population of cycling cells, expressing the gangliosides labeled with the A2B5 antibody, represented a minority population in subcortical white matter, but one of the major cycling populations in cortex, with substantial overlap with O4. Small populations of cycling NG2+ cells also were observed. Thus, the cycling cells in the adult brain are heterogeneous, and the majority appear to belong to glial lineages. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 75–86, 2001
Screening for synaptic defects revealed a locus involved in presynaptic and postsynaptic functions in Drosophila embryos
Authors: Takasu‐Ishikawa Etsuko , Yoshihara Motojiro , Ueda Atsushi , Rheuben Mary B. , Hotta Yoshiki , Kidokoro Yoshiaki
Published: October 2004

To identify genes involved in synaptic functions, we screened lethal enhancer trap lines by monitoring synaptic activities at the neuromuscular junction in Drosophila embryos. It was found that MY7919, thus isolated, has moderate defects in both pre‐ and postsynaptic functions. The mean amplitudes of spontaneous as well as evoked synaptic currents were smaller than those in wild‐type. The failure rate was higher than normal at any given concentration of external Ca2+, indicating that presynaptic functions were impaired. In addition, the mean amplitude of miniature synaptic currents was smaller, and the unitary current amplitudes of junctional glutamate receptor channels were slightly but significantly smaller. Thus, postsynaptic functions were also altered. The gene was cloned and found to be identical to the previously reported apontic (=tracheae defective) locus, which is believed to be a transcription factor expressed in the central nervous system (CNS) as well as in the head, tracheae, and heart. Immunohistochemical analysis using an antiapontic antibody revealed that the protein is localized to nuclei. Null alleles of the apontic locus were obtained by imprecise excision of the enhancer trap vector. Synaptic activities in null mutants were not different from those of the original allele, even though null homozygotes had uncontracted ventral nerve cords and more severe behavioral phenotypes. The morphology of the neuromuscular junction of the null mutant was qualitatively similar to that of wild‐type, with the presence of typical pre‐ and postsynaptic specializations, but with some suggestions of quantitative differences. This strategy for screening mutants with synaptic defects will reveal more genes directly or indirectly affecting synaptic transmission. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 101–119, 2001
Neurotrophins, but not depolarization, regulate substance P expression in the developing optic tectum
Authors: Tu Shichun , Debski Elizabeth A.
Published: October 2004

Neurotransmitter expression can be regulated by both activity and neurotrophins in a number of in vitro systems. We examined whether either of these factors was likely to play a role in the in vivo optic nerve‐dependent regulation of a substance P‐like immunoreactive (SP‐ir) population of cells in the developing optic tectum of the frog. In contrast to our previous results with the adult system, blocking tectal cell responses to glutamate release by retinal ganglion cells with 6‐cyano‐7‐nitroquinoxaline‐2,3 dione (CNQX) did not affect the percent of SP‐ir cells in the developing tectum. Treatment with d‐(‐)‐2‐amino‐5‐phosphonovaleric acid (d‐AP‐5) was also ineffective in this regard, although both it and CNQX treatment disrupted visual map topography. Chronic treatment with brain‐derived neurotrophic factor (BDNF) and neurotrophin‐4/5 (NT‐4/5) produced increases in SP‐ir cells in the treated lobes of normal animals, which were significant in the case of NT‐4/5. Both substances also prevented the decrease of SP cells that would otherwise occur in the deafferented lobe of unilaterally optic nerve‐transected tadpoles. These changes in the percent of SP‐ir cells occurred without any detectable changes in the overall number of tectal cells. NGF had no effect on SP expression. Nor did it affect topographic map formation, which was disrupted by treatment with either BDNF or NT‐4/5. Our results demonstrate that different mechanisms regulate SP expression in the developing and adult tectum. They indicate that neurotrophin levels in the developing optic tectum may selectively regulate a specific neuropeptide‐expressing population of cells. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 131–149, 2001
Prenatal diagnosis of tetrasomy 9p in a 19‐week‐old fetus with Dandy–Walker malformation: a case report
Authors: Deurloo K. L. , Cobben J. M. , Heins Y. M. , de Ru M. , Wijnaendts L. C. D. , van Vugt J. M. G.
Published: October 2004

Objective

The presentation of sonographic and perinatal findings of tetrasomy 9p.

Methods and Results

Chorionic villus sampling and amniocentesis were performed at 19 weeks of gestation because of the sonographic findings of Dandy–Walker malformation with bilateral ventriculomegaly. Cytogenetic analysis showed 47,XX,+i psu dic(9)(pter‐>q12::q12>‐pter). The pregnancy was terminated at 20 weeks of gestation at the request of the parents. At post‐mortem examination, the presumed hypoplasia of the vermis could not be confirmed for technical reasons. No other pathological findings were seen.

Conclusion

From our experience and from the literature, we conclude that Dandy–Walker malformation is an important finding in tetrasomy 9p. Chromosomal studies should be carried out in fetuses with sonographically detected Dandy–Walker malformation, even in the absence of other abnormalities. Copyright © 2004 John Wiley & Sons, Ltd.
Social outcomes of children with AD/HD: Contributing factors and implications for practice
Authors: Stormont Melissa
Published: October 2004

The purposes of this article are to provide a review of the literature in the area of social characteristics of children with AD/HD, and to outline interventions for working with specific social problems. Research has consistently documented that children with AD/HD are more rejected and less accepted by their peers. Possible reasons for this peer rejection will be presented in this article and include inappropriate social behavior, social knowledge deficits and biases, and negative interactions with peers and teachers. Because children with AD/HD are at risk for negative social outcomes, multiple intervention options are necessary. © 2001 John Wiley & Sons, Inc.
Factors affecting treatment acceptability for psychostimulant medication versus psychoeducational intervention
Authors: Stinnett Terry A. , Crawford Stephanie A. , Gillespie Marci D. , Cruce Michael K. , Langford Courtney A.
Published: October 2004

Future teachers' judgments of acceptability for two common treatments for children with the Attention Deficit Hyperactivity Disorder (ADHD) label were examined. One hundred forty‐four pre‐service teachers were grouped according to their high school location at graduation (urban vs. rural) and were randomly assigned to read one of four vignettes. The content of the vignettes was held constant but label (ADHD vs no label) and treatments (special education placement vs. Ritalin) were varied. Results indicated a significant main effect on treatment acceptability for High School Location, a Label × Treatment interaction on the attention problems variable, a main effect for Label on the social problems variable, and a High School Location × Treatment interaction on the social problems variable. A number of implications can be made. Observer characteristics such as urban or rural high school experiences may influence judgments about a labeled child more than the characteristics of the child being observed. In this study, the ADHD label evoked greater expectations of attentional difficulties even when the pattern of functioning was similar to nonlabeled children. On the other hand, children with the ADHD label were judged as having better social functioning, which suggests that the ADHD label allows observers to attribute behavioral difficulties or the social problems displayed by these children to some factor that is outside the control of the child, or for which the child does not have personal responsibility. © 2001 John Wiley & Sons, Inc.
Polysilsesquioxane containing tributylstannyl groups as intermediary derivative for organofunctionalization
Authors: Moriya Osamu , Fukushima Masanori , Sugizaki Toshio , Nakamura Yoshiyuki , Endo Takeshi
Published: October 2004

Poly(phenylsilsesquioxane) containing tributylstannyl groups (TBPSQ) was a useful intermediate for the synthesis of organofunctionalized polysilsesquioxane (2). The reaction of TBPSQ and monochlorosilane (1), which possessed an organofunctional group, proceeded under mild and neutral conditions to give 2 with the elimination of tributylstannylchloride. The combined use of the different chlorosilanes 1 enabled the ready preparation of multifunctionalized polysilsesquioxanes 2. The number‐average molecular weights and dispersions of 2 were almost the same as those of starting TBPSQ. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 286–292, 2002
Ethylene copolymerization with cyclic dienes using rac‐Et[Ind]2ZrCl2–Methylaluminoxane
Authors: Simanke Adriane G. , Mauler Raquel S. , Galland Griselda B.
Published: October 2004

The effect of the copolymerization temperature and amount of comonomer in the copolymerization of ethylene with 1,3‐cyclopentadiene, dicyclopentadiene, and 4‐vinyl‐1‐cyclohexene and the rac‐Et[Ind]2ZrCl2–methylaluminoxane metallocene system was studied. The amount of comonomer present in the reaction media influenced the catalytic activity. Dicyclopentadiene was the most reactive comonomer among the cyclic dienes studied. In general, copolymers synthesized at 60 °C showed higher catalytic activities. Ethylene–dicyclopentadiene copolymers with high comonomer contents (>9%) did not show melting temperatures. 1,3‐Cyclopentadiene dimerized into dicyclopentadiene during the copolymerization, giving a terpolymer of ethylene, cyclopentadiene, and dicyclopentadiene. A complete characterization of the products was carried out with 1H NMR, 13C NMR, heteronuclear chemical shift correlation, differential scanning calorimetry, and gel permeation chromatography. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 471–485, 2002; DOI 10.1002/pola.10133
Anionic ring‐opening polymerization of propylene oxide in the presence of phosphonium catalysts
Authors: Rexin Ornulf , Mülhaupt Rolf
Published: October 2004

Anionic ring‐opening polymerization of propylene oxide in the presence of potassium alcoholate initiator was accelerated by addition of the bulky phosphonium salt tetrakis[cyclohexyl(methyl)amino]phosphonium‐tetrafluoroborate. Dipropylene glycol (DPG) was partially deprotonated (5%) and used as an initiator for the polymerization performed at 100 °C at normal pressure. The delocalization of the positive charge over five atoms promoted the formation of a separated ion pair, thus enhancing nucleophilicity and reactivity. Compared with those of polyaminophosphazenes and tetrabutylphosphonium cation, the average propagation rates increased in the order of Bu4P+, K+, P, P, and tBuP4H+. DPn for the polymers was in the range of 20–64. Characterization of poly(propylene oxide)s by means of 1H NMR, size exclusion chromatography (SEC), and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) showed low polydispersities (Mw/Mn) without any byproducts or impurities. The Mw/Mn obtained was 1.03–1.09 (MALDI‐TOF‐MS) and 1.11–1.15 (SEC), respectively. Values calculated from titration of the hydroxyl groups showed good agreement. Determination of the total degree of unsaturation in the range of 13–60 mmol/kg indicated larger amounts with increasing polymerization rates. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 864–873, 2002; DOI 10.1002/pola.10163
Structure–property relationships in modified natural rubber latexes grafted with methyl methacrylate and vinyl neo‐decanoate
Authors: Lee Doug‐Youn , Subramaniam Nadaraja , Fellows Christopher M. , Gilbert Robert G.
Published: October 2004

A series of modified natural rubber latexes (NRLs) grafted with poly(methyl methacrylate) (PMMA) were prepared by seeded emulsion polymerization with NRL as the seed polymer. Two different redox systems, cumene hydroperoxide (CHP)/tetraethylene pentamine (TEPA) and tert‐butyl hydroperoxide (t‐BHP)/TEPA, were used to initiate polymerization, and phase mixing was promoted by the addition of vinyl neo‐decanoate (VneoD). The CHP/TEPA system was more efficient than t‐BHP/TEPA for the grafting of secondary polymers in modified natural rubber (NR). The enhanced phase mixing in the presence of VneoD was attributed to the solubility parameter of the VneoD‐rich methyl methacrylate–VneoD copolymer formed late in the reaction, lying between that of PMMA and NR, and the extent to which this polymer was grafted to the NR backbone. The viscoelastic properties of the polymers were investigated as a function of composition, temperature, and frequency; changes in viscoelastic behavior consistent with the presence of a high‐Tg PMMA phase (where Tg is the glass‐transition temperature) were observed. This suggested a degree of phase mixing that increased with increasing VneoD content and increasing flux of oxygen‐centered radicals within the NR particles. More phase mixing resulted in poorer film formation, which was consistent with the localization of a high‐Tg secondary polymer phase near the particle surface. The apparent concentration of PMMA near the surface of the particles was also observed with transmission electron microscopy. The localization of PMMA near the particle surfaces was consistent with the presumed locus of radical generation in these systems: the redox couple used to initiate the polymerization consisted of an oil‐soluble hydroperoxide and a water‐soluble amine that reacted predominantly at the water/particle interface. The viscoelastic properties of the modified NRLs that were prepared suggest that these synthetic procedures provide a means of controlling phase mixing and branching, such as for improving the suitability of these modified rubbers in pressure‐sensitive‐adhesive formulations. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 809–822, 2002; DOI 10.1002/pola.10165
Phosphines: Nucleophilic organic catalysts for the controlled ring‐opening polymerization of lactides
Authors: Myers Matthew , Connor Eric F. , Glauser Thierry , Möck Andreas , Nyce Gregory , Hedrick James L.
Published: October 2004

A new metal‐free synthetic approach to the controlled ring‐opening polymerization (ROP) of lactide with nucleophilic phosphines as transesterification catalysts is described. P(Bu)3, PhPMe2, Ph2PMe, PPh3, and related phosphines are commercially available, inexpensive catalysts that generate narrowly dispersed polylactides with predictable molecular weights. These organic catalysts must be used in combination with an initiator, such as an alcohol, to generate an alcoholate ester α‐end group upon ROP. A likely polymerization pathway is through a monomer‐activated mechanism, with minimal active species, facilitating narrow molecular weight distributions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 844–851, 2002; DOI 10.1002/pola.10168
Phenomenological approach to compare the crystallization kinetics of isotactic polypropylene and polyamide‐6 under pressure
Authors: La Carrubba V. , Brucato V. , Piccarolo S.
Published: October 2004

Reliable experimental data for semicrystalline polymers crystallized under pressure are supplied on the basis of a model experiment in which drastic solidification conditions are applied. The influence of the pressure and cooling rate on some properties, such as the density and microhardness, and on the product morphology, as investigated with wide‐angle X‐ray scattering (WAXS), is stressed. Results for isotactic polypropylene (iPP) samples display a lower density and a lower microhardness with increasing pressure over a wide range of cooling rates (from 0.01 to 20 °C/s). Polyamide‐6 (PA6) samples exhibit the opposite behavior, with the density and microhardness increasing at higher pressures over the entire range of cooling rates investigated (from 1 to 200 °C/s). A deconvolution technique applied to iPP and PA6 WAXS patterns has allowed us to evaluate the final phase content and to assess the crystallization kinetics. A negative influence of pressure on the α‐crystalline phase crystallization kinetics can be observed for iPP, whereas a slightly positive influence of pressure on the crystallization kinetics of PA6 can be noted. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 153–175, 2002
Degradation of a poly(ester urethane) elastomer. I. Absorption and diffusion of water in Estane® 5703 and related polymers
Authors: Salazar Michael R. , Thompson Shelley L. , Laintz Kenneth E. , Pack Russell T
Published: October 2004

In preparation for studying the hydrolytic degradation of Estane® 5703 and related poly(ester urethane) elastomers, the absorption (solubility) and diffusion of water in these polymers have been examined experimentally and modeled theoretically. Weight gain and loss experiments have been carried out. The amount of water absorbed per gram of sample was linear at low relative humidities (RHs) but curved upward at higher RHs. This curvature was not fit by Henry's law or the Flory–Huggins equation but was easily fit by a water‐cluster model. Diffusion coefficients were determined by fitting the time dependence of the sample weights, and the diffusion appeared Fickian to within experimental uncertainty. The similarity of related polymers was used to determine the approximate temperature dependence of the absorption. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 181–191, 2002
Mechanical properties of clay‐reinforced polyamide
Authors: Masenelli‐Varlot K. , Reynaud E. , Vigier G. , Varlet J.
Published: October 2004

Intercalated and exfoliated nanocomposites were prepared by extrusion and injection of polyamide‐6 and highly swollen or slightly swollen montmorillonite, respectively. The microstructure of the nanocomposites has been studied previously. In this article, we investigated the influence of the preferential orientation of the montmorillonite sheets on the mechanical properties of the nanocomposites. Dynamic mechanical analysis and tensile tests showed that the elastic modulus depends mainly on the filler loading. A parallel coupling could well account for the behavior of the nanocomposites. The calculated elastic and storage moduli of montmorillonite were set to 140 and 40 GPa, respectively. Compression tests were performed to study the anisotropy of the mechanical properties. The elastic modulus and flow strain were sensitive to the filler orientation. A Tandon–Weng approach was applied to consider the geometry of the filler. In all low‐deformation tests, no significant difference between intercalated and exfoliated systems was observed. Finally, the influence of the dispersion and exfoliation state of the filler on the ultimate properties of the nanocomposites (tensile tests) is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 272–283, 2002
Small‐angle neutron scattering investigation of structural changes in nafion membranes induced by swelling with various solvents
Authors: Young Sandra K. , Trevino S. F. , Beck Tan Nora C.
Published: October 2004

The structure of Nafion‐117 perfluorosulfonate ionomer membranes was investigated with small‐angle neutron scattering techniques. Structural changes induced by the swelling of the membranes with water, alcohols, and dipolar, aprotic solvents were monitored at solvent‐swelling levels ranging from approximately 2 vol % to greater than 50 vol %. Membranes swollen up to approximately 50 vol % solvent exhibited two scattering maxima, one known to be associated with ionic regions of the membrane structure and one known to be associated with correlation distances between crystalline regions in the membrane structure. The positions of both maxima shifted toward lower scattering vector values as the solvent content in the membrane increased. The shift in the position of both maxima was linearly related to the solvent volume fraction in the membrane. The Bragg spacings corresponding to both the ionic‐feature scattering maximum and the crystalline‐feature scattering maximum were plotted versus the solvent volume fraction in the membranes, and the data fit with linear regression. The slopes associated with the curves of the spacing versus the solvent volume fraction were greater for the crystalline‐feature spacing than for the ionic‐feature spacing for all solvents other than water; this was indicative of preferential segregation of nonaqueous solvents into regions of the structure not directly associated with the ionic scattering maximum. © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 387–400, 2002; DOI 10.1002/polb.10092
Morphological study on water‐borne conducting polyaniline‐poly(ethylene oxide) blends
Authors: Wang Yanju , Wang Xianhong , Li Ji , Zhang Hongfang , Mo Zhishen , Jing Xiabin , Wang Fosong
Published: October 2004

Conducting polyaniline‐poly(ethylene oxide) blends were prepared from their aqueous solutions. The blends displayed an electrical conductivity percolation threshold as low as 1.83 wt % of polyaniline loading. As demonstrated by scanning electron microscopy, polarized optical microscopy, and wide‐angle X‐ray diffraction studies, the conducting polyaniline took a fibrillar morphology in the blend, and it existed only in the amorphous phase of poly(ethylene oxide). A three‐phase model combining morphological factors instead of a two‐phase model was proposed to explain the low‐conductivity percolation threshold. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 605–612, 2002; DOI 10.1002/polb.10114
Interaction parameters of crystalline/crystalline polypropylene/poly(butene‐1) blends: Effect of molecular fractionation
Authors: Shieh Yeong‐Tarng , Lee Mao‐Song , Chen Show‐An
Published: October 2004

Compatibility of crystalline/crystalline polypropylene (PP)/poly(butene‐1) (PB‐1) blends was investigated via the method of equilibrium melting temperature depression followed by determining the polymer–polymer interaction parameter (χ) using the Nishi–Wang equation. The composition variation of the equilibrium melting temperatures of blends (T) was determined with the Hoffman–Weeks plot. The T and its variation with the blend composition depended on the crystallization temperature range. The morphological effect of the blend composition was not a contribution factor for the T depressions of PP and PB‐1 in the blends. The interplay of the dilution effect and molecular fractionation effect of the amorphous component on crystallization of the crystalline component in the blends governed the relation of T with the blend composition. The calculated χ values were negative depending on the blend composition. The negative χ values suggested that PP and PB‐1 in the amorphous region were compatible. The composition variation of the χ values was attributed to the molecular fractionation effect during crystallization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 638–648, 2002; DOI 10.1002/polb.10125
Cystic fibrosis: Keeping it in the family*
Authors: Crowley Suzanne , Bush Andrew
Published: October 2004

Nearly all men with cystic fibrosis (CF) are infertile, although assisted conception has allowed an increasing number of women with CF to become pregnant. We report on the case of a couple investigated for infertility who conceived a child with CF. The father had previously undergone a laparotomy for meconium peritonitis as a neonate, and the mother had recently been given a diagnosis of asthma. Both parents fulfilled the United States Cystic Fibrosis Foundation diagnostic criteria for cystic fibrosis. We discuss the mild CF phenotype and the impact of the diagnosis on this family. Pediatr Pulmonol. 2002; 33:158–161. © 2002 Wiley‐Liss, Inc.
Effects of intrabronchial foreign body retention
Authors: Yildizeli Bedrettin , Zonüzi Ferzat , Yüksel Mustafa , Kodalli Nihat , Çakalağaoğlu Fulya , Küllü Sevgi
Published: October 2004

Unrecognized bronchial foreign bodies (Fbs) cause irreversible changes in the airways. However, the exact course of these changes is not well‐known. We developed an animal model of bronchial obstruction to radiologically and histopathologically assess the development of postobstructive pulmonary changes. A piece of peanut was placed in the airways of 21 rabbits through a 2.5‐mm rigid bronchoscope. Animals were divided into three groups (groups I–III) that were sacrificed on day 3,10, and 30 after Fb placement, respectively.

Prior to sacrifice, since there were no differences between the groups prior to Fb placement, computerized tomography (CT) of the lung was taken, and the lungs were harvested for histologic analysis under light microscope. In group I, leukocyte infiltration around the bronchial wall (P = 0.0003) and edema (P = 0.0384) around the alveolar septa were the predominant histological findings. The CT scan was normal. In group II and group III, increased amounts of mononuclear cells and macrophage infiltration around the bronchial wall were observed (P = 0.0008, P = 0.0409, respectively). There were no differences in presence of granuloma formation, emphysema, atelectasis, or thickness of alveolar septa among the three groups. The CT scan of group II showed consolidations plus minimal bronchial dilatation in the involved lung of the rabbits (P not significant). Bronchial cartilage destruction was seen in 4 out of 7 rabbits in group III (P = 0.0071).

We conclude that 30‐day retention of intrabronchial peanut caused bronchial cartilage destruction and fibrosis that were attributed as bronchiectatic changes in the airways of the lung parenchyma. Therefore, any case with suspected foreign body aspiration should be treated immediately to prevent possible irreversible changes of the lungs. Pediatr Pulmonol. 2002; 33:362–367. © 2002 Wiley‐Liss, Inc.
A clade of trypsins found in cold‐adapted fish
Authors: Roach Jared C.
Published: October 2004

A clade of trypsins, known as group III, is identified by phylogenetic analysis. These trypsins occur in fish that spend all or part of their lives at temperatures near 0°C and may represent extreme psychrophilic enzymes. A principal component analysis of amino acid compositions distinguishes group III from mesophilic trypsins, as do molecular trees and multidimensional scaling of molecular sequence distances. The primary sequences of group III trypsins, in conjunction with the known structures of mesophilic trypsins, permit insight into function and mechanisms of cold adaption. The techniques employed are broadly applicable to phylogenies characterized by a markedly different, or “fast‐evolving,” clade. An updated lactate dehydrogenase molecular tree illustrates an additional fast‐evolving clade. Proteins 2002;47:31–44. © 2002 Wiley‐Liss, Inc.
Protein–protein docking of electron transfer complexes: Cytochromecoxidase and cytochromec
Authors: Flöck Dagmar , Helms Volkhard
Published: October 2004

Electron transferring protein complexes form only transiently and the crystal structures of electron transfer protein–protein complexes involving cytochromeccould so far be determined only for the pairs of yeast cytochromecperoxidase (CcP) with iso‐1‐cytochromec(iso‐1‐cytc) and with horse heart cytochromec(cytc). This article presents models from computational docking for complexes of cytochromecoxidase (COX) fromParacoccus denitrificanswith horse heart cytochromec, and with its physiological counterpart cytochromec552 (c552). Initial docking is performed with the FTDOCK program, which permits an exhaustive search of translational and rotational space. A filtering procedure is then applied to reduce the number of complexes to a manageable number. In a final step of structural and energetic refinement, the complexes are optimized by rigid‐body energy minimization with the molecular mechanics package CHARMM. This methodology was first tested on the CcP:iso‐1‐cytccomplex, in which the complex with the lowest CHARMM energy has an RMSD from the crystal structure of only 1.8 Å (Cαcarbon atoms). Notably, the crystal conformation has an even lower energy. The same procedure was then applied to COX:cytcand COX:c552. The lowest‐energy COX:cytccomplex is very similar to a docking model previously described for the complex of bovine cytochromecoxidase with horse heart cytochromec. For the COX:c552 complex, cytochromec552 is found in two different orientations, depending on whether it is docked against COX from a two‐subunit or from a four‐subunit crystal structure, respectively. Both conformations are discussed critically in the light of the available experimental data. Proteins 2002;47:75–85. © 2002 Wiley‐Liss, Inc.
Ab initio prediction of protein structure using LINUS
Authors: Srinivasan Rajgopal , Rose George D.
Published: October 2004

LINUS is an ab initio method for the prediction of protein structure based on simple physical principles. Here we report the performance of LINUS at CASP4, a communitywide experiment to predict protein structure in which participants are blinded to the structures they seek to predict. We submitted 13 predictions for this experiment. The best four are described in detail, together with an assessment of secondary structure prediction for the entire set. Coordinates for all predictions are available from the CASP web site (http://predictioncenter.llnl.gov). It should be emphasized that our use of the descriptor “ab initio” is unequivocal: the sole input into these simulations is the amino acid sequence. Proteins 2002;47:489–495. © 2002 Wiley‐Liss, Inc.
Emergence of highly designable protein‐backbone conformations in an off‐lattice model
Authors: Miller Jonathan , Zeng Chen , Wingreen Ned S. , Tang Chao
Published: October 2004

Despite the variety of protein sizes, shapes, and backbone configurations found in nature, the design of novel protein folds remains an open problem. Within simple lattice models it has been shown that all structures are not equally suitable for design. Rather, certain structures are distinguished by unusually high designability: the number of amino acid sequences for which they represent the unique lowest energy state; sequences associated with such structures possess both robustness to mutation and thermodynamic stability. Here we report that highly designable backbone conformations also emerge in a realistic off‐lattice model. The highly designable conformations of a chain of 23 amino acids are identified and found to be remarkably insensitive to model parameters. Although some of these conformations correspond closely to known natural protein folds, such as the zinc finger and the helix‐turn‐helix motifs, others do not resemble known folds and may be candidates for novel fold design. Proteins 2002;47:506–512. © 2002 Wiley‐Liss, Inc.
ConsDock: A new program for the consensus analysis of protein–ligand interactions
Authors: Paul Nicodème , Rognan Didier
Published: October 2004

Protein‐based virtual screening of chemical libraries is a powerful technique for identifying new molecules that may interact with a macromolecular target of interest. Because of docking and scoring limitations, it is more difficult to apply as a lead optimization method because it requires that the docking/scoring tool is able to propose as few solutions as possible and all of them with a very good accuracy for both the protein‐bound orientation and the conformation of the ligand. In the present study, we present a consensus docking approach (ConsDock) that takes advantage of three widely used docking tools (Dock, FlexX, and Gold). The consensus analysis of all possible poses generated by several docking tools is performed sequentially in four steps: (i) hierarchical clustering of all poses generated by a docking tool into families represented by a leader; (ii) definition of all consensus pairs from leaders generated by different docking programs; (iii) clustering of consensus pairs into classes, represented by a mean structure; and (iv) ranking the different means starting from the most populated class of consensus pairs. When applied to a test set of 100 protein–ligand complexes from the Protein Data Bank, ConsDock significantly outperforms single docking with respect to the docking accuracy of the top‐ranked pose. In 60% of the cases investigated here, ConsDock was able to rank as top solution a pose within 2 Å RMSD of the X‐ray structure. It can be applied as a postprocessing filter to either single‐ or multiple‐docking programs to prioritize three‐dimensional guided lead optimization from the most likely docking solution. Proteins 2002;47:521–533. © 2002 Wiley‐Liss, Inc.
NADH interactions with WT‐ and S94A‐acyl carrier protein reductase from Mycobacterium tuberculosis: An ab initio study
Authors: Pantano Sergio , Alber Frank , Lamba Doriano , Carloni Paolo
Published: October 2004

We present an ab initio molecular dynamics study of the complex between acyl carrier protein reductase InhA from M. tuberculosis and isonicotinic acid hydrazide‐NADH. We focus on wild‐type (WT) InhA and a mutant causing drug resistance (S94A) for which structural information is available (Rozwarski et al., 1998;279:98–102; Dessen et al., 1995;267:1638–1641). Our calculations suggest that the water‐mediated H‐bond interactions between Ser94 side chain and NADH, present in WT InhA X‐ray structure, can be lost during the dynamics. This conformational change is accompanied by a structural rearrangement of Gly14. The calculated structure of WT is rather similar to the X‐ray structure of the S94A mutant in terms of geometrical parameters and chemical bonding. Further evidence for the mobility of Ser94 is provided by a 1‐ns‐long classical molecular dynamics on the entire protein. The previously unrecognized high mobility of Ser94 can provide a rationale of the small change in free binding energies on passing from WT to S94A InhA. Proteins 2002;47:62–68. © 2002 Wiley‐Liss, Inc.