bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of methyl substituents on the stability of 1‐aza‐2‐adamantanone, Kirby's most twisted amide
Authors: Morgan Kathleen M. , Rawlins M. Logan , Montgomery Margo N.
Published: October 2004

Hydrolysis and carbonyl hydration of adamantane‐based twisted amide 1 were studied computationally. The importance of the bridgehead methyl substituents on these reactions was determined. The carbonyl hydration of 1 is structurally and energetically much like the hydration of a transition state to amide CN bond rotation. However, hydrolysis of 1 to the amino acid is dependent on the bridgehead methyl substituents and less like hydrolysis of an amide transition state. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of phosphate buffer on the kinetics of glycation of proteins
Authors: Gil Herminia , Salcedo Daniel , Romero Román
Published: October 2004

The glycation of γ‐globulin is catalyzed by phosphate buffer, whereas that of human serum albumin (HSA) and ovalbumin is not. The observed rate constant of spontaneous glycation of HSA is twofold larger than ovalbumin and γ‐globulin. When D‐glucose‐2‐h is compared with D‐glucose‐2‐d, the overall kinetic isotope effect for the buffer‐independent rates is Hk0/Dk0 = 4.43 ± 0.06 for HSA. The substrate isotope effect for the buffer‐independent term excludes proton abstraction as the rate‐determining step in the Amadori rearrangement by phosphate buffer. Catalysis by phosphate buffer of the glycation of γ‐globulin indicates that phosphate is the abstracting base in the Amadori rearrangement. These results suggest that the phosphate buffer plays a fundamental role in the glycation of γ‐globulin. Copyright © 2004 John Wiley & Sons, Ltd.
Characterization of different reverse micelle interfaces using the reaction of 4‐fluoro‐3‐nitrobenzoate with piperidine
Authors: Correa N. Mariano , Durantini Edgardo N. , Silber Juana J.
Published: October 2004

The characterization of different reverse micellar interfaces, benzene–sodium 1,4‐bis‐2‐ethylhexylsulfosuccinate (AOT)–water and benzene–benzyl‐n‐hexadecyldimethylammonium chloride (BHDC)–water, were studied using an aromatic nucleophilic substitution reaction, SNAr, between acid 4‐fluoro‐3‐nitrobenzoic (FNBA) and piperidine. The reaction was also studied in homogeneous media, water and benzene, varying the ionic strength in the aqueous solution. The kinetic profiles were investigated as a function of variables such as surfactant, amine concentration and the amount of water dispersed in the reverse micelles, W0 = [water]/[surfactant]. In the pure solvents, water and benzene, there is no genuine base‐catalyzed reaction. In water the reaction is faster than in benzene, owing to the better stabilization of the intermediate Z. Also, the reaction rate in water is accelerated by the addition of salt. In both micellar systems FNBA is totally incorporated in the interface of the aggregate because, under the working conditions of excess of amine, it is ionized to carboxylate, The reactions kinetics in these media can be quantitatively explained taking into account the distribution of the nucleophile between the bulk solvent and the micelle interfaces. In the AOT reverse micelles at W0 = 10, the anionic substrate seems to be located in the water side of the interface whereas in BHDC it resides in the oil side of the interface. The results were used to evaluate the intrinsic second‐order rate coefficient of the SNAr reaction at the interface. From these data, properties such as micropolarity and ionic strength of this environment can be deduced. Hence, as expected, the micropolarity of the reverse micelles systems is higher than that of pure benzene and increases upon water addition. In the AOT system and owing to the location of the probe, the average ionic strength of the AOT reverse micelles could be estimated and a value of around 4.5 M was found. Copyright © 2004 John Wiley & Sons, Ltd.
Highly organosoluble and flexible polyimides with color lightness and transparency based on 2,2‐bis[4‐(2‐trifluoromethyl‐4‐aminophenoxy)‐3,5‐dimethylphenyl]propane
Authors: Liaw Der‐Jang , Chang Feng‐Chyuan
Published: October 2004

A new diamine containing isopropylidene, methyl substituted arylene ether, and trifluoromethyl groups, 2,2‐bis[4‐(2‐trifluoromethyl‐4‐aminophenoxy)‐3,5‐dimethylphenyl]propane (BTADP), was synthesized and used in preparation of a series of polyimides by direct polycondensation with various aromatic tetracarboxylic dianhydrides in N, N‐dimethylacetamide (DMAc). All polymers derived from diamine (BTADP) with trifluoromethyl substituents were highly organosoluble in the solvents, like N‐methyl‐2‐pyrrolidinone (NMP), N,N‐dimethylacetamide, N,N‐dimethylformamide (DMF), pyridine, chloroform, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dichloromethane, cyclohexanone, and γ‐butyrolactone at room temperature or upon heating at 70 °C. Inherent viscosities of the polyimides were found to range between 0.58 and 0.97 dL·g−1. These polyimides had glass transition temperatures between 256 and 307 °C, and their 10% mass loss temperatures ranged from 440 to 462 °C and 421 to 443 °C under nitrogen and air, respectively. These polyimides had low dielectric constants in the range of 2.84–3.09. All the polyimides could be cast into films from DMAc solutions and were thermally converted into color lightness, optically transparent, flexible, and tough polyimides. The polyimide films had a tensile strength in the range of 83–97 MPa and a tensile modulus in the range of 2.0–2.2 GPa. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5766–5774, 2004
Synthesis and properties of biomimetic poly(L‐glutamate)‐b‐poly(2‐acryloyloxyethyllactoside)‐b‐poly(L‐glutamate) triblock copolymers
Authors: Dong Chang‐Ming , Faucher Keith M. , Chaikof Elliot L.
Published: October 2004

A novel class of biomimetic glycopolymer–polypeptide triblock copolymers [poly(L‐glutamate)–poly(2‐acryloyloxyethyllactoside)–poly(L‐glutamate)] was synthesized by the sequential atom transfer radical polymerization of a protected lactose‐based glycomonomer and the ring‐opening polymerization of β‐benzyl‐L‐glutamate N‐carboxyanhydride. Gel permeation chromatography and nuclear magnetic resonance analyses demonstrated that triblock copolymers with defined architectures, controlled molecular weights, and low polydispersities were successfully obtained. Fourier transform infrared spectroscopy of the triblock copolymers revealed that the α‐helix/β‐sheet ratio increased with the poly(benzyl‐L‐glutamate) block length. Furthermore, the water‐soluble triblock copolymers self‐assembled into lactose‐installed polymeric aggregates; this was investigated with the hydrophobic dye solubilization method and ultraviolet–visible analysis. Notably, this kind of aggregate may be useful as an artificial polyvalent ligand in the investigation of carbohydrate–protein recognition and for the design of site‐specific drug‐delivery systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5754–5765, 2004
Hollow latex particles as submicrometer reactors for polymerization in confined geometries
Authors: Brand Thorsten , Ratinac Kyle , Castro Jeffrey V. , Gilbert Robert G.
Published: October 2004

A method was developed for free‐radical polymerization in the confines of a hollow latex particle. Hollow particles were prepared via the dynamic swelling method from polystyrene seed and divinylbenzene and had hollows of 500–1000 nm. So that these hollow poly(divinylbenzene) particles could function as submicrometer reactors, the particles were filled with a monomer (N‐isopropylacrylamide) via the dispersion of the dried particles in the molten monomer. The monomer that was not contained in the hollows was removed by washing and gentle abrasion. Free‐radical polymerization was then initiated by γ radiolysis in the solid state. Transmission electron microscopy showed that poly(N‐isopropylacrylamide) formed in the hollow interior of the particles, which functioned as submicrometer reactors. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5706–5713, 2004
Explicit‐chain model of native‐state hydrogen exchange: Implications for event ordering and cooperativity in protein folding
Authors: Kaya Hüseyin , Chan Hue Sun
Published: October 2004

Native‐state hydrogen exchange experiments on several proteins have revealed partially unfolded conformations with diverse stabilities. These equilibrium observations have been used to support kinetic arguments that folding proceeds via a sequential “pathway.” This interpretative logic is evaluated here by analyzing the relationship between thermodynamic behavior and folding kinetics in a class of simplified lattice protein models. The chain models studied have varying degrees of cooperative interplay (coupling) between local helical conformational preference and favorable nonlocal interactions. When model cooperativity is high, as native conditions are weakened, “isotherms” of free energy of exchange for residues belonging to the same helix merge together before global unfolding. The point of merger depends on the model energetic favorability of the helix. This trend is similar to the corresponding experimental observations. Kinetically, we find that the ordering of helix formation in the very last stage of native core assembly tends to follow the stabilities of their converged isotherms. In a majority (but not all) of folding trajectories, the final assembly of helices that are thermodynamically more stable against exchange precedes that of helices that are less stable against exchange. These model features are in partial agreement with common experimental interpretations. However, the model results also underscore the ensemble nature of the folding process: the kinetics of helix formation is not a discrete, strictly “all‐or‐none” process as that envisioned by certain non‐explicit‐chain models. Helices generally undergo many cycles of partial formation and dissolution before their conformations are fixed in the final assembly stage of folding, a kinetic stage that takes up only ∼2% of the average folding time in the present model; and the ordering of the helices' final assembly in some trajectories can be different from the dominant ordering stipulated by the exchange isotherms. Proteins 2005. © 2004 Wiley‐Liss, Inc.
The dynamic behaviour of stacked shipping units during transport. Part 1: model validation
Authors: Rouillard Vincent , Sek Michael A. , Crawford Shayne
Published: October 2004

This paper deals with the dynamic behaviour of stacked packaging units when subjected to vertical vibrational inputs as experienced in transport vehicles. Although the vibrational performance of single‐unit packaging systems has been thoroughly studied, the behaviour of stacked packaging units is not fully understood. The complexity of the problem is compounded when the effects of vertical restraints are taken into account. The paper presents the development of a numerical computer model designed to predict the dynamic response of stacked package systems when subjected to vertical vibrational excitation. Provisions have been made to account for the effects of vertical restraint tension and stiffness. In addition, a physical model representative of a generic stacked packaging system has been developed to assist in validating the numerical model. The paper includes results from preliminary experiments in which the frequency response functions of the models were evaluated and compared. The validity of the numerical model in the time domain was tested using random burst excitation signals. These preliminary experiments reveal that, when the effects of frictional damping are taken into account, the numerical model can be used to generate reasonably accurate predications of the dynamic behaviour of the equivalent physical system. Copyright © 2004 John Wiley & Sons, Ltd.
Flexural stiffness of selected corrugated structures
Authors: Lee Myung Hoon , Park Jong Min
Published: October 2004

Top‐to‐bottom compression strength of a corrugated fibreboard box is partly dependent on the load‐carrying ability of central panel areas of the box. The ability of these central panel areas to resist a bending force from loading may increase the stacking strength of the box. The difference in the compression strengths of boxes that have identical dimensions and were fabricated with identical components but different flute types, is primarily caused by flexural stiffness of the box panels. Top‐to‐bottom compression strength of boxes can be accurately predicted by flexural stiffness measurements and edge crush test (ECT) of the combined boards. This study was carried out to analyse the flexural stiffness, to measure bending force and bending deflection by a four‐point bending test for various corrugated fibreboards, and to provide the major constructional factors which play a role in improving the compression strength of the box. Copyright © 2004 John Wiley & Sons, Ltd.
Next generation of ab initio energy density functionals: Thoughts and facts from solvable models
Authors: March N. H.
Published: October 2004

After a brief summary of trends revealed in the presentations of this DFT Conference, especially on ab initio energy density functionals and potentials, some emphasis will be given to the likely “next generation” of first‐principles energy density functionals. The Slater exchange potential V(r) then seems a natural starting point, being related to the Dirac exchange energy density εx(r) and the ground‐state density n(r) by V(r) = 2εx(r)/n(r). We then discuss various “corrections” to this Slater potential V(r). Although usually small compared with the exchange potential, the correlation contribution Vc(r) remains difficult to treat from first principles, but we refer to a few directions stemming from (generally two‐electron) solvable models. Finally, we give some attention to the kinetic energy, especially the single‐particle functional Ts[n] but also, again though from simple examples, to the correlation kinetic energy. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
High‐throughput chiral analysis of albuterol enantiomers in dog plasma using on‐line sample extraction/polar organic mode chiral liquid chromatography with tandem mass spectrometric detection
Authors: Wu Steven T. , Xing Jinsong , Apedo Atsu , Wang‐Iverson David B. , Olah Timothy V. , Tymiak Adrienne A. , Zhao Ning
Published: October 2004

An automated chiral chromatography/tandem mass spectrometry bioanalytical method for the determination of albuterol in dog plasma was developed. The method employed on‐line sample extraction using turbulent flow chromatography coupled to a Chirobiotic T column for chiral separation using a polar organic mobile phase consisting of methanol, 0.02% formic acid, and 0.1% ammonium formate. The analytes were detected by a tandem mass spectrometer operated in positive ion mode. The (S)‐ and (R)‐isomers were resolved chromatographically with retention times of 5.1 and 5.6 min, respectively. The analytical run time was 8 min. The enantiomers did not interconvert either in mobile phase or in dog plasma at room temperature over the course of at least 2 h. The assay has a linear dynamic range from 2.5–2500 nM for both enantiomers. The lower limit of quantitation (LLOQ) was 2.5 nM for both enantiomers using 50 μL of plasma. The accuracy and precision of intraday validation were determined at five concentration levels of six replicates. The accuracy of the method for the (R)‐isomer ranged from 94–103% of nominal concentrations, and the precision (%CV) ranged from 3.6–12%. The accuracy of the method for the (S)‐isomer ranged from 94.5–108% of nominal concentrations, and the precision ranged from 3.2–9.3%. Interday accuracy and precision were evaluated for three days at five concentrations for one replicate. The accuracy of the method for the (R)‐isomer ranged from 98–110% of nominal concentrations, and the precision ranged from 1.5–10.6%. The accuracy of the method for the (S)‐isomer ranged from 96–104% of nominal concentrations, and the precision ranged from 1.5–8.7%. The combination of turbulent flow on‐line sample extraction with polar organic mode chiral chromatography provided a specific, rugged, and high‐throughput method for the chiral analysis of albuterol in biological fluids. Copyright © 2004 John Wiley & Sons, Ltd.
Diagnostic protein discovery using proteolytic peptide targeting and identification
Authors: Koomen John M. , Zhao Haitao , Li Donghui , Abbruzzese James , Baggerly Keith , Kobayashi Ryuji
Published: October 2004

Plasma protein profiling with mass spectrometry is currently being evaluated as a diagnostic tool for cancer and other diseases. These experiments consist of three steps: plasma protein fractionation, analysis with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS), and comparisons of the MALDI profiles to develop diagnostic fingerprints using bioinformatic techniques. While preliminary results appear promising in small sample groups, the method is limited by the sensitivity of MALDI‐MS for intact proteins, the limited mass range of MALDI‐MS, and difficulties associated with isolating individual proteins for identification to validate the diagnostic fingerprint. Here we present an alternative and improved method directed toward diagnostic protein discovery, which incorporates proteolytic peptide profiling, bioinformatic targeting of ion signals, and MALDI tandem mass spectrometry (MS/MS) peptide sequencing, rather than fingerprinting. Pancreatic cancer patients, pancreatitis patients, and controls are used as the model system. Profiling peptides after enzymatic digestion improves sensitivity and extends the accessible protein molecular weight range when compared to intact protein profiling. The first step is to extract and fractionate the proteins from plasma. Each fraction is digested with trypsin and subsequently analyzed by MALDI‐MS. Rather than using bioinformatic analysis as a pattern‐matching technique, peptides are targeted based on the disease to control peak intensity ratios measured in the averages of all mass spectra in each group and t‐tests of the intensity of each individual peak. The targeted peptide ion signals are subsequently identified using MALDI‐MS/MS in quadrupole‐TOF and tandem‐TOF instruments. This study found not only the proteins targeted and identified by a previous protein profiling experiment, but also detected additional proteins. These initial results are consistent with the known biology of pancreatic cancer or pancreatitis, but are not specific to those diseases. Copyright © 2004 John Wiley & Sons, Ltd.
Rapid determination of amino acids in neonatal blood samples based on derivatization with isobutyl chloroformate followed by solid‐phase microextraction and gas chromatography/mass spectrometry
Authors: Deng Chunhui , Li Ning , Zhang Xiangmin
Published: October 2004

The purpose of this study was to develop a simple, rapid and sensitive analytical method for determination of amino acids in neonatal blood samples. The developed method involves the employment of derivatization and a solid‐phase microextraction (SPME) technique together with gas chromatography/mass spectrometry (GC/MS). Amino acids in blood samples were derivatized by a mixture of isobutyl chloroformate, methanol and pyridine, and the N(O,S)‐alkoxycarbonyl alkyl esters thus formed were headspace extracted by a SPME fiber. Finally, the extracted analytes on the fiber were desorbed and detected by GC/MS in electron impact (EI) mode. L‐Valine, L‐leucine, L‐isoleucine, L‐phenylanaline and L‐tyrosine in blood samples were quantitatively analyzed by measurement of the corresponding N(O,S)‐alkoxycarbonyl alkyl esters using an external standard method. SPME conditions were optimized, and the method was validated. The method was applied to diagnosis of neonatal phenylkenuria (PKU) and maple syrup urine disease (MSUD) by the analyses of five amino acids in blood samples. The results showed that the proposed method is a potentially powerful tool for simultaneous screening for neonatal PKU and MSUD. Copyright © 2004 John Wiley & Sons, Ltd.
An algorithm for model‐based stable pupil detection for eye tracking system
Authors: Takegami Takeshi , Gotoh Toshiyuki , Ohyama Ghen
Published: October 2004

This paper considers eye images observed by a system such as an infrared eye‐movement observation system in which the relative position of the head and camera is kept constant. A highly accurate detection method for the pupil image is proposed. Assuming that the eyeball has a spherical shape and the contour of the pupil is a circle, the pupil is observed as an ellipse accompanying movement of the eyeball. By accurately detecting this pupil image of elliptical shape, it is possible to detect the eye direction stably. Various methods of detecting an ellipse have been presented, and the Hough transform is one of these. The Hough transform has the feature that it is less affected by noise and occlusion. In the detection of ellipses in general, the number of degrees of freedom is represented by five parameters to be determined, which may produce problems of computational complexity and memory requirements. On the other hand, in order that the pupil may rotate around the eyeball center, the pupil image observed depends on a position and a direction from the eyeball center, without becoming general ellipse form. In this study, the above constraint is utilized, and an algorithm is discussed in which the pupil is detected with high accuracy based on the eyeball model. In the algorithm, the processing efficiency of the whole system is considered. In the algorithm, first, initial detection of the pupil is performed by ellipse fitting based on the edges in multiple observed images, and the parameters of the eyeball model are estimated on the basis of the results. Then, the Hough transform is applied on the basis of the estimated eyeball parameters, and the pupil contour is detected with high accuracy. The experimental results show that the accuracy and stability of pupil contour detection is improved, indicating that the proposed method is effective. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(13): 21–31, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10544
Missing links in sustainable food production in west Africa: the case of the savannas of northern Nigeria
Authors: Chianu Jonas N. , Tsujii Hiroshi
Published: October 2004

This paper evaluates six sustainable agricultural production practices (crop–livestock integration, cereal–legume intercropping, organic plus inorganic fertilizer combination, improved crop germplasm, improved livestock breeds and soil/water conservation) being promoted in sub‐Saharan Africa (SSA), using data from 160 farmers from northern Nigeria. The aim was to determine the missing links that have prevented increase in food production, poverty reduction and household food security expected from these practices. Results indicate weak crop–livestock integration (due to low manure production, inadequate ruminants, low production of cowpea and groundnut and low adoption of improved strip cropping), labor allocation bias against livestock production, cereal crop domination, low cereal–legume intercropping and use of fertilizers, limited combination of organic and inorganic fertilizer, low adoption of improved crop germplasm and absence of improved livestock. The paper concludes with recommendations to harness benefits from improved agricultural practices in the study area and similar ecologies in SSA. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment.
Which infertile women should be indicated for sonohysterography?
Authors: Ando H. , Toda S. , Harada M. , Yoshida S. , Kondo I. , Masahashi T. , Mizutani S.
Published: October 2004

Objective

To evaluate the indications for transvaginal saline contrast sonohysterography (TV‐SCSH) in endometrial screening by transvaginal sonography in infertile women.

Methods

The study involved 850 consecutive infertile women presenting to an outpatient clinic. Using transvaginal ultrasound endometrial images were evaluated in the proliferative phase. Abnormal images were classified as follows: rugged (R), hyperechoic (H), waved (W), or thick (T). Clinical symptoms such as hypermenorrhea, dysmenorrhea and abnormal uterine bleeding were also recorded. Abnormal endometrial images were further evaluated on TV‐SCSH. Age‐matched women with normal endometrial images underwent TV‐SCSH as controls.

Results

The endometrial pattern was abnormal in 111 patients (13.1%). Lesions that had been identified by TV‐SCSH including endometrial polyps (44 cases), submucosal myomata (29 cases), and intramural myomata with mucosal extension (24 cases) were largely associated with the R and/or the H pattern, the W or the T pattern, and the W pattern, respectively. Sensitivity and specificity of the abnormal endometrial image for any lesion were 100% and 91.5%, respectively. Sixty‐four patients (59.3%) were asymptomatic despite an abnormal endometrial image.

Conclusions

TV‐SCSH should be performed on selected patients following assessment of endometrial images on transvaginal sonography in order to diagnose intra‐ and pericavitary lesions in infertile women. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Plasma electrolyte concentrations in captive and free‐ranging African penguins (Spheniscus demersus) maintained with and without dietary salt supplements
Authors: Mazzaro Lisa M. , Tuttle Allison , Wyatt Jeff , Goodman Jeremy , Kadyszewski Edmund , Dunn J. Lawrence
Published: October 2004

African penguins (Spheniscus demersus) are common display animals in North American zoos and aquariums. At present, 43 American Zoo and Aquarium Association (AZA)‐accredited institutions maintain over 700 of these birds. A survey of facilities found that only seven institutions maintain their birds in “saltwater habitats” (natural, brine, or artificial seawater systems), while the remaining institutions provide freshwater habitats. Penguins maintained in freshwater habitats commonly receive dietary salt supplements, though evidence is lacking as to the value of this practice. This study was designed to evaluate the necessity of salt supplementation in African penguins. We report the results of a randomized, 10‐month comparison of plasma electrolytes (Na, Cl, and K) between groups of 10 salt‐supplemented and nonsupplemented birds living in a freshwater environment. The results showed no significant differences between the two groups. An interfacility comparison at the same time points revealed temporal pattern differences in analyte values between the facilities; however, the absolute concentrations did not exceed clinical ranges found in healthy birds. Furthermore, single time‐point comparisons between wild and captive African penguins indicated similar sodium concentrations, while potassium and chloride concentrations varied between groups. Finally, the plasma electrolyte levels in 20 birds remained statistically unchanged after a 60‐day withdrawal from salt supplementation. This study provides experimental evidence that African penguins maintained in freshwater exhibits on a herring‐, capelin‐, and squid‐based diet do not require salt supplementation. In addition to the practical implications regarding the need for salt supplementation for captive birds, the results also have theoretical significance. They provide evidence that penguins do not need to ingest high salt concentrations to remain in electrolyte balance. In this regard, the ion regulatory mechanisms in penguins are similar to those in terrestrial mammals and birds. Zoo Biol 23:397–408, 2004. © 2004 Wiley‐Liss, Inc.
Stereotypic behavior in Asiatic black and Malayan sun bears
Authors: Vickery Sophie , Mason Georgia
Published: October 2004

The stereotypies of individually caged Asiatic black bears (Ursus thibetanus) and Malayan sun bears (Helarctos malayanus) were studied in detail. Stereotypies were performed by 27 of the 29 subjects, were primarily locomotory in form (e.g., pacing), and occupied on average 18% (standard error of the mean (SEM)=2.5) of daylight hours. Stereotypy levels during the night were almost negligible and were highly correlated with daytime levels. Total stereotypies peaked prior to food arrival, although oral stereotypies were most frequent after feeding. In general, stereotypies were performed in locations from which food arrival could be viewed, although Asiatic black bears were equally likely to exhibit stereotypy near a neighboring bear. Across individuals, stereotypy frequency was inversely correlated with inactivity and increased with age. Older bears also showed less normal activity and a reduced diversity of normal behavior. Stereotypy levels were unrelated to levels of “compulsive” behavior (e.g., hair plucking) or repetitive self‐sucking–a potential deprivation stereotypy. More frequent stereotypies were performed more invariantly (i.e., were more predictable from one repetition to the next) and in more diverse contexts, namely 1) outside the pre‐feeding period, and 2) during the night. Contrary to observations reported elsewhere, higher frequencies of stereotypy were not associated with reduced behavioral diversity, or with a more elaborate repertoire of stereotypy forms and sequences. Although the two species did not differ in overall frequency, the stereotypies of sun bears appeared to be more food‐motivated than those of Asiatic black bears: the sun bears displayed a higher frequency and diversity of oral stereotypies, and higher levels of pre‐feeding stereotypy, and performed significantly more of their total stereotypies in locations from which they could view food arrival. This study demonstrates how analyzing stereotypies in detail can help identify the motivations that underlie these behaviors, and potentially reveal their degree of establishment–both of which are important factors in stereotypy treatment. Zoo Biol 23:409–430, 2004. © 2004 Wiley‐Liss, Inc.
Extracorporeal Photopheresis Differentially Regulates the Expression or Phosphorylated STAT-1 and STAT-5 in Treated Monocytes and T Cells, Respectively
Authors: Bladon John , Taylor Peter
Published: October 2004

Background

Extracorporeal photopheresis (ECP) is effective in conditions with opposing immune etiology. ECP induces an immunomodulatory response through simultaneous monocyte activation and apoptosis induction of lymphocytes. However, ECP is also immunosuppressive, downregulating proinflammatory cytokines. Signal transducers and activators of transcription (STATs) are important mediators of cell-signaling systems, including cytokines. Ultraviolet (UV) immunosuppression is linked to reductions in cytokine-induced STAT phosphorylation.

Objective

The aim of this study was to find whether ECP downregulates STAT phosphorylation.

Methods

Pre- and post-ECP mononuclear cells from cutaneous T-cell lymphoma and chronic graft-versus-host disease patients were stimulated with either IFNγ, IL2, or IL15. The percentage of IFNγ-stimulated monocytes positive for phosphorylated STAT-1 (pSTAT-1) and the number of IL2- and IL15-stimulated T cells expressing phosphorylated STAT-5 (pSTAT-5) were determined at 0 and 24 h.

Results

Post-ECP, pSTAT-1 levels in monocytes remained unchanged; however, at 24 h post-ECP the number of T cells expressing pSTAT-5 was reduced.

Conclusion

Following ECP, monocytes retain their ability to phosphorylate STAT-1, while pSTAT-5 expression is lost in lymphocytes. This differential effect of ECP may account for the diverse population of diseases that benefit.
The Canadian Dermatology Workforce Survey: Implications for the Future of Canadian Dermatology—Who will be your skin expert?
Authors: Maguiness Sheilagh , Searles Gordon E. , From Lynn , Swiggum Susan
Published: October 2004

Objective

To survey Canadian dermatologists for specialty-specific physician resource information including demographics, workload and future career plans.

Background and methods

In 2001, the Canadian Dermatology Association (CDA) surveyed 555 dermatologists in Canada to gain specialty-specific physician resource information. Three hundred and seventy-one dermatologists (69%) provided information about themselves, their workloads and their future career goals.

Results

The average Canadian dermatologist is 52 years old and 35% of practicing dermatologists are over the age of 55. Eighty-nine percent of dermatologists practice in an urban setting, 19% include practice in a rural setting while less than 0.5% practice in remote areas. Canadian dermatologists spend 61% of their clinical time providing services in Medical Dermatology. Within 5 years, 50% of dermatologists reported that they plan to reduce their practices or retire.

Conclusion

The Canadian Dermatology Workforce Survey provides a snapshot of the current practice of dermatology in Canada. It also serves to highlight the critical shortage of dermatologists, which will continue to worsen without immediate, innovative planning for the future.
Annular Lichen Planus
Authors: Sakakibara Kanako , Nakada Tokio , Sueki Hirohiko , lijima Masafumi , Irisawa Kaikichi
Published: October 2004

Background

Annular lichen planus is a clinical variant of lichen planus, and its characteristic lesions are annular plaques consisting of a narrow rim of activity and a depressed center.

Objective

This article presents two cases of annular lichen planus, a 39-year-old woman and a 45-year-old woman.

Methods and Results

In both cases, lesions developed mainly on the femoral regions. Histopathological specimens from the margin of the lesion demonstrated liquefaction degeneration of the epidermis and band-like infiltrate of lymphocytes in the upper dermis, whereas there was very mild infiltrate in the upper dermis from the center. In the center, elastic fibers were more fragmented and less numerous than in the margin. Although topical corticosteroid tape was effective for one case, new lesions developed several times over two years in the other.

Conclusion

Our findings suggest that this clinical behavior is from elastolysis as a result of inflammation.
Understanding the parts in terms of the whole
Authors: Cornish‐Bowden Athel , Cárdenas María Luz , Letelier Juan‐Carlos , Soto‐Andrade Jorge , Abarzúa Flavio Guíñez
Published: October 2004

Abstract Metabolism is usually treated as a set of chemical reactions catalysed by separate enzymes. However, various complications, such as transport of molecules across membranes, physical association of different enzymes, giving the possibility of metabolite channelling, need to be taken into account. More generally, a proper understanding of the nature of life will require metabolism to be treated as a complete system, and not just as a collection of components. Certain properties of metabolic systems, such as feedback inhibition of the first committed step of a pathway, make sense only if one takes a broader view of a pathway than is usual in textbooks, so that one can appreciate ideas such as regulation of biosynthesis according to demand. More generally still, consideration of metabolism as a whole puts the emphasis on certain systemic aspects that are crucial but which can pass unnoticed if attention is always focussed on details. For example, a living organism, unlike any machine known or conceivable at present, makes and maintains itself and all of its components. Any serious investigation of how this can be possible implies an infinite regress in which each set of enzymes needed for the metabolic activity of the organism implies the existence of another set of enzymes to maintain them, which, in turn, implies another set, and so on indefinitely. Avoiding this implication of infinite regress represents a major challenge for future investigation.
Speculations on the evolution of 9+2 organelles and the role of central pair microtubules
Authors: Mitchell David R.
Published: October 2004

Abstract Motility generated by 9+2 organelles, variably called cilia or flagella, evolved before divergence from the last common ancestor of extant eukaryotes. In order to understand better how motility in these organelles is regulated, evolutionary steps that led to the present 9+2 morphology are considered. In addition, recent advances in our knowledge of flagellar assembly, together with heightened appreciation of the widespread role of cilia in sensory processes, suggest that these organelles may have served multiple roles in early eukaryotic cells. In addition to their function as undulating motility organelles, we speculate that protocilia were the primary determinants of cell polarity and directed motility in early eukaryotes, and that they provided the first defined membrane domain for localization of receptors that allowed cells to respond tactically to environmental cues. Initially, motility associated with these protocilia may have been gliding motility rather than the more complex bend propagation. Once these protocilia became functional motile organelles for beating, we believe that addition of an asymmetric central apparatus, capable of transducing signals to dynein motors and altering beat parameters, provided refined directional control in response to tactic signals. This paper presents hypothesized steps in this evolutionary process, and examples to support these hypotheses.
Testing the Geometric Clutch hypothesis
Authors: Lindemann Charles B.
Published: October 2004

Abstract The Geometric Clutch hypothesis is based on the premise that transverse forces (t‐forces) acting on the outer doublets of the eukaryotic axoneme coordinate the action of the dynein motors to produce flagellar and ciliary beating. T‐forces result from tension and compression on the outer doublets when a bend is present on the flagellum or cilium. The t‐force acts to pry the doublets apart in an active bend, and push the doublets together when the flagellum is passively bent and thus could engage and disengage the dynein motors. Computed simulations of this working mechanism have reproduced the beating pattern of simple cilia and flagella, and of mammalian sperm. Cilia‐like beating, with a clearly defined effective and recovery stroke, can be generated using one uniformly applied switching algorithm. When the mechanical properties and dimensions appropriate to a specific flagellum are incorporated into the model the same algorithm can simulate a sea urchin or bull sperm‐like beat. The computed model reproduces many of the observed behaviors of real flagella and cilia. The model can duplicate the results of outer arm extraction experiments in cilia and predicted two types of arrest behavior that were verified experimentally in bull sperm. It also successfully predicted the experimentally determined nexin elasticity. Calculations based on live and reactivated sea urchin and bull sperm yielded a value of 0.5 nN/μm for the t‐force at the switch‐point. This is a force sufficient to overcome the shearing force generated by all the dyneins on one micron of outer doublet. A t‐force of this magnitude should produce substantial distortion of the axoneme at the switch‐point, especially in spoke or spoke‐head deficient motile flagella. This concrete and verifiable prediction is within the grasp of recent advances in imaging technology, specifically cryoelectron microscopy and atomic force microscopy.
Management of breech presentation in areas with high prevalence of HIV infection
Authors: Holmes W.R. , Hofmeyr G.J.
Published: October 2004

Objective

To provide recommendations for the management of breech presentation in areas of high prevalence of human immunodeficiency virus (HIV) infection.

Method

Review of relevant literature.

Results

Studies show that elective cesarean section (CS) is safer than vaginal delivery for breech presentation, external cephalic version (ECV) at term increases the chance of vaginal cephalic delivery. Although there are no studies of the risk of mother‐to‐child transmission of HIV from ECV, indirect evidence suggests that any increased risk is likely to be very small.

Recommendations

Where CS is available and safe, HIV‐positive women, or women who might be at risk of HIV, with a fetus at term with breech presentation, should be offered elective CS to reduce the risks of both vaginal breech delivery and mother‐to‐child HIV infection. HIV‐negative women can be offered ECV at term to try to avoid CS. Where women do not have access to a safe CS, or prefer vaginal delivery, the benefit for both mother and child of attempting ECV at term is likely to outweigh the theoretical, very small, risk of facilitating HIV transmission.
LAGEOS asymmetric reflectivity and corner cube reflectors
Authors: Vokrouhlický D. , Métris G.
Published: October 2004

Accurate laser tracking of LAGEOS satellites, allows investigation together with gravitational effects, a number of fine nongravitational perturbations in their orbit. Several of these forces are reasonably interpreted in terms of known physical phenomena. Postulated asymmetry in reflectivity of LAGEOS hemispheres is an exception. Here we show that in spite of a recent suggestion, this empirical effect cannot be explained by differential sunlight reflection on germanium and fused silica corner cube reflectors. The true nature of this effect remains puzzling.
Tropopause folding at satellite‐observed spatial gradients: 2. Development of an empirical model
Authors: Wimmers A. J. , Moody J. L.
Published: October 2004

We develop an empirical model that estimates the horizontal distribution of tropopause folds based primarily on a robust relationship between upper tropospheric specific humidity gradients and tropopause folding. The specific humidity gradients are resolved by the altered water vapor (AWV) product, developed from the GOES imager water vapor channel. Unexpectedly, no proportional relationship was found between tropopause fold size and AWV gradient magnitude beyond the one‐to‐one occurrence of strong gradients at tropopause folds. This indicates that tropopause folds do not commonly reach a “steady state” mass of ozone inside the fold. Rather, the mass of air must be controlled at least as much by the age of the fold and dynamical dispersion mechanisms that are not linearly related to the strength of the corresponding tropopause depression. This has important implications for the interpretation of lidar imagery and in situ ozone data at tropopause folds. In lieu of this result, a uniform fold size is assigned at all locations of modeled folding on the basis of the average of the folds used in parameterization. The model estimates the distribution of actively developing and residual tropopause folds, which is a useful method of tracking the dispersal of all stratospherically enhanced air in the troposphere and is unique to this observation‐based model of tropopause folding.
Calculation of radiative fluxes from the surface to top of atmosphere based on ISCCP and other global data sets: Refinements of the radiative transfer model and the input data
Authors: Zhang Yuanchong , Rossow William B. , Lacis Andrew A. , Oinas Valdar , Mishchenko Michael I.
Published: October 2004

We continue reconstructing Earth's radiation budget from global observations in as much detail as possible to allow diagnosis of the effects of cloud (and surface and other atmospheric constituents) variations on it. This new study was undertaken to reduce the most noticeable systematic errors in our previous results (flux data set calculated mainly using International Satellite Cloud Climatology Project–C1 input data (ISCCP‐FC)) by exploiting the availability of a more advanced NASA Goddard Institute for Space Studies (GISS) radiative transfer model and improved ISCCP cloud climatology and ancillary data sets. The most important changes are the introduction of a better treatment of ice clouds, revision of the aerosol climatology, accounting for diurnal variations of surface skin/air temperatures and the cloud‐radiative effects on them, revision of the water vapor profiles used, and refinement of the land surface albedos and emissivities. We also extend our previous flux results, limited to the top of atmosphere (TOA) and surface (SRF), to also include three levels within the atmosphere, forming one integrated vertical atmospheric flux profile from SRF to TOA, inclusive, by combining a new climatology of cloud vertical structure with the ISCCP cloud product. Using the new radiative transfer model and new input data sets, we have produced an 18‐year at 3‐hour time steps, global at 280‐km intervals, radiative flux profile data set (called ISCCP‐FD) that provides full‐ and clear‐sky, shortwave and longwave, upwelling and downwelling fluxes at five levels (SRF, 680 mbar, 440 mbar, 100 mbar, and TOA). Evaluation is still only possible for TOA and SRF fluxes: Comparisons of monthly, regional mean values from FD with Earth Radiation Budget Experiment, Clouds and the Earth's Radiant Energy System and Baseline Surface Radiation Network values suggest that we have been able to reduce the overall uncertainties from 10–15 to 5–10 W/m2 at TOA and from 20–25 to 10–15 W/m2 at SRF. Annual mean pressure‐latitude cross sections of the cloud effects on atmospheric net radiative fluxes show that clouds shift the longwave cooling downward in the Intertropical Convergence Zone, acting to stabilize the tropical atmosphere while increasing the horizontal heating gradient forcing the Hadley circulation, and shift the longwave cooling upward in the midlatitude storm zones, acting to destabilize the baroclinic zones while decreasing the horizontal heating gradient there.
Water vapor retrieval over ocean using near‐infrared radiometry
Authors: Dubuisson P. , Dessailly D. , Vesperini M. , Frouin R.
Published: October 2004

A methodology is presented and evaluated to retrieve vertically integrated water vapor content over the ocean in any viewing geometry from POLDER data. The methodology is based on differential absorption by water vapor in the near‐infrared. Over the ocean, except in sun glint conditions, surface reflectance is small, and interaction between aerosol scattering and water vapor absorption is exploited to estimate total water vapor content. A sensitivity study performed with an accurate radiative transfer code (GAME) shows that a determination of total water vapor content is theoretically possible if the optical thickness and scale height of aerosols are known. An inaccuracy of 0.1 to 0.6 g cm−2 is expected, depending on water vapor content. The aerosol optical thickness δa at 865 nm is available from POLDER standard products. The aerosol scale height Ha can be estimated from the surface pressure derived from POLDER oxygen channels at 763 and 765 nm. A retrieval scheme is devised using parameterizations calculated using GAME for water vapor and surface pressure. The inversion scheme is applied to 20 POLDER orbits with observed water vapor contents ranging from 0.2 to 6 g cm−2. Comparisons with SSM/I estimates indicate a RMS error ranging from 0.21 to 0.58 g cm−2, depending on water vapor content, with a mean RMS error of 0.44 g cm−2. This result is slightly larger than deviations obtained between POLDER and SSM/I during the POLDER standard product validation over ocean in sun glint conditions (mean RMS error of 0.42 g cm−2).