bluuebunny/crossref_metadata_2025 huggingface dataset:
Pain tolerance in upper limb disorders: findings from a community survey
Authors: Mitchell S , Reading I , Walker-Bone K , Palmer K , Cooper C , Coggon D
Published: February 2003

Aims:To test the hypothesis that non-specific upper limb pain arises from altered pain perception with reduced tolerance of sensory stimuli.

Methods:Subjects undergoing clinical examination as part of a community based survey of upper limb disorders were invited to return for an assessment of pain tolerance. A standardised algorithm was used to classify the 94 participants according to whether they had specific upper limb disorders (n = 22), non-specific arm pain (n = 15), or no arm pain (n = 57). Pain tolerance was assessed at three anatomical sites in each arm in response to electrocutaneous stimulation with alternating currents up to a maximum of 10 mA at three frequencies (5, 250, and 2000 Hz). A proportional odds model was used to compare pain tolerance thresholds according to sex, age, and diagnosis.

Results:Women were less tolerant of pain than men (OR 0.13) and tolerance also declined with age (OR for one year increase in age 0.97). After allowance for sex and age, there was no indication that pain tolerance was lower in subjects with non-specific arm pain than in those with specific upper limb disorders or those who had no arm pain.

Conclusions:The study hypothesis was not supported. However, before the hypothesis is dismissed, it should be tested further in patients with more severe and disabling arm pain.
Relation between colour vision loss and occupational styrene exposure
Authors: Viaene M K
Published: February 2003

This commentary relates to the study by Gonget al, published in the December 2002 issue of this journal.1
40Ar/39Ar evidence for ca. 1800 Ma tectonothermal activity along the Great Falls tectonic zone, central Montana
Authors: Holm Daniel , Schneider David
Published: February 2003

Late Paleoproterozoic (19001600 Ma) tectonothermal activity on all borders of the Archean Wyoming Province has long been established by low-precision KAr and RbSr studies. However, recent tectonic models advanced for supercontinent aggregation require improved constraints on the timing of tectonothermal activity along major boundaries. On its northwestern boundary, the Great Falls tectonic zone separates the Archean Wyoming and Hearne provinces. Recently published U/Pb ages and geochemical data reveal the presence of a Paleoproterozoic (ca. 1860 Ma) marginal-arc magmatic complex along a portion of the Great Falls tectonic zone in central Montana. We present nine new 40Ar/39Ar mineral ages (on hornblende and biotite) from these same arc rocks, which indicate ca. 1800 Ma thermal activity (>500°C) and subsequent rapid cooling to below 300°C by 1775 Ma. This new data set constrains the timing of WyomingHearne collision to between 1860 and 1800 Ma and the timing of last significant tectonothermal activity of this portion of the Great Falls tectonic zone (18001775 Ma). We note that our data add to a growing geochronologic database indicating ca. 1800 Ma tectonothermal activity (via either initial suturing or continued tectonic activity) associated with Paleoproterozoic docking of the Wyoming Province with Laurentia.
The Frasnian-Famennian (mid-Late Devonian) boundary in the type section of the Long Rapids Formation, James Bay Lowlands, northern Ontario, Canada
Authors: Levman Bryan G , Bitter Peter H von
Published: February 2003

Utilizing a combination of conodont-based biostratigraphy and geochemistry, the FrasnianFamennian (F/F, mid-Late Devonian) boundary was located in the Long Rapids Formation, northern Ontario. It is present in a black shale sequence, 21.46 m above the base of the Long Rapids Formation, just above a carbonate bed that has similarities to the Upper Kellwasser Limestone, recognized as a lithological marker for the F/F boundary in Germany, Belgium, and France. There is no evidence of an impact event, and sedimentation across the boundary is continuous, although there is a discontinuity layer just below the boundary and the early part of the linguiformis Zone (of the standard Late Devonian conodont zonation) is missing. Strong positive δ 13C (organic and carbonate) values were identified and are interpreted as evidence of mass mortality in anoxic waters at the F/F extinction; positive δ18O values suggest the extinction was also accompanied by a temperature drop. Negative δ34S values also indicate anoxia, and negative δ15N values provide evidence of reduced surface-water productivity. No iridium anomaly was found at the boundary, although higher than usual values were found about 85 cm below the F/F boundary. Sedimentological and biological evidence in the Long Rapids Formation indicates that the F/F extinction was coincident with major sea-level fluctuations in the late Frasnian, including a transgression beginning at the end of the linguiformis Zone and continuing through the Early triangularis Zone and beyond. Marine oscillations were accompanied by anoxia, which appears to be the killing mechanism for the conodont and other end Frasnian extinctions.
The Dorothy bentonite: an extraordinary case of secondary thickening in a late Campanian volcanic ash fall in central Alberta
Authors: Lerbekmo J F
Published: February 2003

The late Campanian (~73 Ma) Dorothy bentonite outcrops in the marine Bearpaw Shale for 20 km along the Red Deer River valley east of Drumheller, Alberta, and is up to 13.5 m thick. An isopach map based upon 230 sub surface and surface thickness measurements illustrates an elongated southwestnortheast lobe with maximum dimensions of about 300 km by 50 km. The volume is ~57 km3 distributed within an area of ~11 000 km2. This bentonite is the altered product of what is believed to be a short-lived Plincan-type eruption from part of the Howell Creek Instrusives in southeastern British Columbia. Fortuitous preservation of the original ash in an up to 2.5 m thick calcite-cemented tuffaceous zone near the middle of the bentonite shows the original ash to have been >99% glass shards and pumice. The remainder of the ash is a crystal component consisting mostly of plagioclase and biotite. The silica content of the isotropic glass shards of about 77%, and a refractive index of 1.503 ± 0.001, suggest a magma of rhyolitic composition.
Early Turonian (Late Cretaceous) age of the Tuskoola sandstone Pine River area, northeastern British Columbia
Authors: Stelck C R , Moore W E , Pemberton S G
Published: February 2003

The presence of Watinoceras reesidei Warren, Watinoceras coloradoense (Henderson), Watinoceras thompsonense Cobban, and Mytiloides mytiloides (Mantell) within the Tuskoola sandstone beds of the Vimy Member of the Kaskapau (Blackstone) Formation, places these strata within the lower Turonian stage of the Upper Cretaceous, within the Watinoceras reesidei Zone. International discoveries of Watinoceras in the United States, the Arctic, west Africa, northern Africa, Europe, and Asia, in the past fifty years has allowed the authors, while updating the stratigraphy and taxonomy, to refine correlation of the Tuskoola sandstone, a sandy facies of the "Second White Specks" horizon of Western Canada.
Relationships between lithofacies belts and conodont faunas, Gun River Formation (Lower Silurian), Anticosti Island, Quebec: a statistical approach
Authors: Zhang Shunxin , Barnes Christopher R , Pohler Susanne ML
Published: February 2003

Discriminant analysis of 80 samples from the Western Carbonate Platform Facies and the Eastern Transitional CarbonateSiliciclastic Platform Facies of the Gun River Formation (Lower Silurian) on Anticosti Island, Quebec, indicates the degree to which different conodont communities were related to particular lithofacies. The statistical analysis reveals that during most of the Gun River Formation deposition, the conodont distributional pattern of the Western Carbonate Platform Facies and the Eastern Transitional CarbonateSiliciclastic Platform Facies of the formation remained stable, and that the boundary of the two facies oscillated eastward and westward. The analysis indicates quantitatively that Icriodella deflecta had a nearshore environmental preference, whereas Rexroadus kentuckyensis tended to reside in offshore environments. These two species play the most important role in differentiating conodont communities and determining the relationship between conodont communities and lithofacies among all of the 22 species known from the Gun River Formation.
Kimberlites from the Wawa area, Ontario
Authors: Kaminsky Felix V , Sablukov Sergei M , Sablukova Ludmila I , Shchukin Vladimir S , Canil Dante
Published: February 2003

Two newly discovered kimberlites from the Wawa area, Ontario, are Group-1 kimberlites in their petrographic, mineralogical, geochemical, and isotopic features. They contain mantle minerals and xenoliths of the FeTi-association (magnesian ilmenite, iron-rich olivine, orange Ti-pyrope garnet, augite, and ferroan enstatite) and of the Cr-association (chromian spinel, forsteritic olivine, purple Cr-pyrope garnets, chromian diopside, and enstatite); minerals of FeTi-association are much more abundant. Minerals of eclogitic association are absent. Both G-10 pyrope garnets and high Cr spinels typically associated with diamond are represented in the Cr-association. The average age of the kimberlites is 1097 ± 7 Ma; i.e., contemporaneous with other alkaline igneous rocks in the Wawa area. Equilibration pressures and temperatures of mantle xenoliths plot close to a 4045 mW m2 geotherm. On the basis of the Ni-in-garnet geothermometer, garnets from the Wawa kimberlites equilibrated at 8001350°C, and at least in part within the diamond stability field. It is likely that kimberlitic magma was derived from light rare earth-element-enriched asthenospheric mantle.
Geochemistry and tectonic significance of alkalic mafic magmatism in the Yukon-Tanana terrane, Finlayson Lake region, Yukon
Authors: Piercey Stephen J , Mortensen James K , Murphy Donald C , Paradis Suzanne , Creaser Robert A
Published: February 2003

This paper provides an integrated field and geochemical study of weakly alkalic, ~360 Ma mafic rocks from the YukonTanana terrane in the Finlayson Lake region, southeastern Yukon. These mafic rocks occur as dykes and sills that crosscut older felsic metavolcanic rocks and metasedimentary rocks (Kudz Ze Kayah unit) or as flows interlayered with carbonaceous metasedimentary rocks. The mafic rocks have signatures similar to those of ocean-island basalts, moderate TiO2 and P2O5 contents, elevated high field strength element and light rare earth element contents, and εNd350 = +1.1. A subset of the dykes (group 4b) has similar geochemical characteristics but with higher Th/Nb and lower Nb/U ratios, higher Zr and light rare earth element contents, and εNd350 = 2.8. The geochemical and isotopic attributes of these rocks are consistent with formation from either lithospheric or asthenospheric sources during decompression melting of the mantle, with some rocks exhibiting evidence for crustal contamination (group 4b). The alkalic basalts are interpreted to represent ~360 Ma ensialic back-arc rifting and basin generation. It is envisioned that east-dipping subduction, represented by slightly older magmatic suites (Fire Lake unit), was disrupted by subduction hinge roll-back, westward migration of arc magmatism, and the onset of back-arc extension. Decompression melting of the mantle associated with back-arc generation resulted in mantle melting and the formation of the alkalic basalts. The spatial association of this mafic magmatism with crustally derived felsic volcanic rocks and contained volcanogenic massive sulphide mineralization suggests that the associated deposits (Kudz Ze Kayah, GP4F) formed within an ensialic back-arc environment.
A new dicynodont therapsid from the lowermost Beaufort Group, Upper Permian of South Africa
Authors: Modesto Sean P , Rubidge Bruce S , Welman Johann
Published: February 2003

Two fragmentary skulls from the Upper Permian Tapinocephalus Assemblage Zone (Abrahamskraal Formation, Beaufort Group) in Eastern Cape Province, South Africa, represent a new dicynodont taxon. Lanthanocephalus mohoii gen. et sp. nov. is distinguished from other dicynodonts by the presence of a conspicuous laterally facing excavation on the dorsal surface of the postfrontal, by dorsal expansions of the supraoccipital that contact the parietals, and by extensive ossification of the lateral wall of the braincase. Lanthanocephalus features several characters that are suggestive of a close relationship with Endothiodon. These include a transversely narrow intertemporal region, the presence of a pineal boss, and the presence of a distinct boss on the ventral margin of the jugal. Cladistic analysis of a modified data matrix from the literature supports the hypothesis of a sister-group relationship between Lanthanocephalus and Endothiodon. However, this grouping and most others found in the analysis collapse with one extra step, weaknesses that underscore the need for further research on dicynodonts and other non-mammalian synapsids.
Urea and KCl have differential effects on enzyme activities in liver and muscle of estivating versus nonestivating species
Authors: Cowan Kyra J , Storey Kenneth B
Published: February 2003

The effects of 300 mM urea or 300 mM KCl on the maximal activities of 25 enzymes of intermediary metabolism were assessed in extracts of liver and muscle from spadefoot toads (Scaphiopus couchii), leopard frogs (Rana pipiens), and rats to assess their sensitivity to these osmolytes. During estivation, toads can lose ~50% of total body water, and urea, which is known for its action as a protein denaturant, accumulates to 200300 mM. The data show that the maximal activities of toad liver enzymes were not affected when assayed in the presence of 300 mM urea in vitro whereas urea inhibited the activities of seven enzymes in frog and 11 enzymes in rat liver. High KCl affected 12 or 13 enzymes in liver of each species causing inhibition in eight or nine cases each, and for frog and rat enzymes, inhibition was frequently more pronounced than for urea. Both urea and KCl affected enzyme activities in muscle extracts of all three species, but whereas their effects were largely negative for frog and rat enzymes, the enzymes affected by urea or KCl in toad muscle were primarily activated by these osmolytes (six out of nine enzymes affected by urea and eight of 15 enzymes affected by KCl). Urea, KCl, and polyethylene glycol (a protein crowding agent) also had species-specific effects on the dissociation constant (Ka) for cAMP of protein kinase A. The data suggest that the accumulation of urea by water-stressed anurans not only contributes to minimizing cell volume reduction, but by doing so also limits the increase in intracellular ionic strength that occurs and thereby helps to minimize the potential inhibitory effects of high salts on metabolic enzymes.Key words: estivation, desiccation, urea, polyethylene glycol, spadefoot toad, leopard frog.
Detection of multiple splice variants of the nuclear protein phosphatase 1 regulator sds22 in rat liver nuclei
Authors: Tran Hue T , Bridges Dave , Ulke Annegret , Moorhead Greg B.G
Published: February 2003

Antipeptide antibodies generated against the N terminus of the protein phosphatase 1 (PP1) binding protein sds22 detected at least four forms of the protein in a rat liver nuclear extract. Four of these immunoreactive bands likely correspond to four predicted forms of sds22 that are generated by alternative splicing. These four proteins are expressed at different levels and appear to be localized exclusively in the nucleus, and two of these proteins copurify with PP1 on the protein phosphatase affinity matrix microcystinSepharose. Two higher molecular mass nuclear proteins that are immunoreactive with the sds22 antibodies also copurify on microcystinSepharose and may be novel forms of sds22 expressed in mammalian cells.Key words: sds22, protein phosphatase 1 (PP1), nucleus, microcystinSepharose.
Increased reactive oxygen species production with antisense oligonucleotides directed against uncoupling protein 2 in murine endothelial cells
Authors: Duval Carine , Nègre-Salvayre Anne , Doglio Alain , Salvayre Robert , Pénicaud Luc , Casteilla Louis
Published: February 2003

Uncoupling protein 2 (UCP-2) belongs to the mitochondrial anion carrier family. It is ubiquitously expressed but is most abdundant in the reticuloendothelial system. In addition to uncoupling function, UCP-2 modulates the production of reactive oxygen species (ROS) by isolated mitochondria. Using an antisense oligonucleotide strategy, we investigated whether a defect in UCP-2 expression modulates ROS in intact endothelial cells. Murine endothelial cells (CRL 2181) pretreated by antisense oligonucleotides directed against UCP-2 mRNA exhibited a significant and specific increase in membrane potential and intracellular ROS level compared with control scrambled or anti-UCP-1 and -UCP-3 antisense oligonucleotides. These specific changes induced by UCP-2 antisense oligonucleotides were correlated with a rise in extracellular superoxide anion production and oxidative stress assessed by thiobarbituric acid reactive substance values. Taken together, these data suggest a role for UCP-2 in control of ROS production and subsequent oxidation of surrounding compounds mediating oxidative stress of endothelial cells. These data also support the notion that manipulations of UCP-2 at the genetic level could control ROS metabolism at the cellular level.Key words: UCP-2, reactive oxygen species, LDL oxidation, oxidative stress, mitochondria, endothelial cells.
Secretion of foreign proteins mediated by chicken lysozyme gene regulatory sequences
Authors: Lampard Gregory R , Gibbins Ann M. Verrinder
Published: February 2003

Exploitation of the insulating properties of the complete chicken lysozyme gene domain may facilitate the production of transgenic chicken bioreactors with the capacity to deposit valuable proteins in the egg white. Chimeric genes consisting of the chicken lysozyme gene regulatory sequences and sequences encoding foreign proteins could be inserted randomly into the chicken genome and retain appropriate expression levels. The research reported here established that chicken lysozyme gene regulatory sequences can be used to direct the production and secretion of green fluorescent protein (used as a reporter protein) in transiently transfected chicken blastodermal cells. Attempts to verify these findings in transgenic hens are currently in progress. To provide a rapid means of generating constructs encoding other foreign proteins under the control of lysozyme gene regulatory sequences that can facilitate the secretion of heterologous proteins in vivo, a generic lysozyme gene regulatory scaffold was created using a poxvirus-mediated gene targeting system.Key words: chicken lysozyme gene, secretion, homologous recombination.
High-mobility group protein 2 may be involved in the locus control region regulation of the β-globin gene cluster
Authors: Lv Xiang , Xu Dong-dong , Liu De-pei , Li Lei , Hao De-long , Liang Chih-chuan
Published: February 2003

Expression regulation of the β-globin gene cluster is a result of synergistic interactions between cis-elements and trans-acting factors. Previous studies usually concentrated on the core sequence of each hypersensitive site in the locus control region of the β-globin gene cluster. But more and more evidence illustrates that the flanking regions are indispensable also. Using electrophoretic mobility shift assay and solid-phase DNase I footprinting methods, we identified a small nuclear protein from K562 cells that binds specifically to the first AT-rich region flanking the hypersensitive site 2 core sequence of the human β-globin gene locus control region. N-terminal sequencing of the enriched protein proved that it is a member of the high-mobility group protein 2 family. This indicates that the AT-rich region in human hypersensitive site 2 may take part in the regulation of the β-globin gene cluster by facilitating DNA bending, which is a prerequisite for the looping mechanism in this region.Key words: β-globin gene, locus control region, hypersensitive site 2, AT-rich region, high-mobility group protein 2.
Regulatory properties of p105: a novel PKC isoenzyme in mantle tissue from marine mussels
Authors: Mercado Luis , Cao Asunción , Barcia Ramiro , Ramos-Martinez Juan Ignacio
Published: February 2003

Previous results suggested operative similarities between Apl II from nervous cells of Aplysia californica, εPKC from brain of vertebrates, and p105 from mantle tissue of Mytilus galloprovincialis Lmk., all of them belonging to the nPKC family. The optimal substrate for Apl II and p105 from mussel is protamine sulfate. In contrast, Ca2+inhibits p105 but does not affect Apl II. As occurs in other εPKC, p105 is autophosphorylable; however, in Apl II, no P-Tyr residues are detected in the most phosphorylated form. The presence of p105 in all the tissues of M. galloprovincialis studied, proves the important, yet unknown, physiological role that this enzyme must play.Key words: protein kinase C, mussel, Mytilus, regulation.
The oligomeric state, complex formation, and chaperoning activity of Hsp70 and Hsp80 ofNeurospora crassa
Authors: Britton M E , Kapoor M
Published: February 2003

Molecular chaperones perform vital cellular functions under normal growth conditions and protect cells against stress-induced damage. The stress proteins Hsp70 and Hsp80 of Neurospora crassa were extracted from heat-shocked mycelium, purified to near homogeneity, and examined with respect to their oligomeric state, complex formation, and chaperoning properties. Their oligomeric state was assessed by dynamic light-scattering measurements, and both Hsp70 and Hsp80 were observed to form a range of soluble, high-molecular-mass protein aggregates. Direct interaction between Hsp70 and Hsp80 was studied by partial tryptic digestion and surface plasmon resonance (SPR). Hsp70 was immobilized on the sensor chip surface, and the binding of Hsp80 in solution was followed in real time. Proteolytic digestion revealed that Hsp70Hsp80 complex formation results in conformational changes in both proteins. The data from SPR studies yielded an equilibrium dissociation constant, KD, of 8.5 × 109M. The chaperoning ability of Hsp70, Hsp80, and Hsp70Hsp80 was monitored in vitro by the protection of citrate synthase from thermal aggregation. The binding of nucleotides modulates the oligomeric state, chaperoning function, and hetero-oligomeric complex formation of Hsp70 and Hsp80.Key words: molecular chaperones, surface plasmon resonance, dynamic light scattering, trypsin digestion, citrate synthase, Neurospora crassa.
Cellular resistance to bleomycin inSaccharomyces cerevisiaeis not affected by changes in bleomycin hydrolase levels
Authors: Wang Huijie , Ramotar Dindial
Published: February 2003

Bleomycin is a glycopeptide drug that exerts potent genotoxic potential and is highly effective in the treatment of certain cancers when used in combination therapy. Unfortunately, however, tumors often develop resistance against bleomycin, and the mechanism of this resistance remains unclear. It has been postulated that bleomycin hydrolase, a protease encoded by the BLH1 gene in humans, may account for tumor resistance to bleomycin. In support of such a notion, earlier studies showed that exogenous expression of yeast Blh1 in human cells can enhance resistance to bleomycin. Here we show that (i) yeast blh1Δ mutants are not sensitive to bleomycin, (ii) bleomycin-hypersensitive yeast mutants were no more sensitive to this agent upon deletion of the BLH1/LAP3/GAL6 gene, and (iii) overproduction of Blh1 in either the parent or bleomycin-hypersensitive mutants did not confer additional resistance to these strains. Therefore, yeast Blh1 apparently has no direct role in protecting this organism from the lethal effects of bleomycin, even though the enzyme can degrade the drug in vitro. Clearly, additional studies are required to establish the actual biological role of Blh1 in yeast.Key words: yeast, bleomycin hydrolase, bleomycin, DNA damage, resistance.
Effects of lactic acid and NaCl on creatine kinase from rabbit muscle
Authors: Tang Hong-Min , Ou Wen-Bin , Zhou Hai-Meng
Published: February 2003

The lactic acid induced unfolding and the salt-induced folding of creatine kinase (CK) were studied by enzyme activity, fluorescence emission spectra, circular dichroism spectra, and native polyacrylamide gel electrophoresis. The results showed that the kinetics of CK inactivation was a monophase process. Lactic acid caused inactivation and unfolding of CK with no aggregation during CK denaturation. The unfolding of the whole molecule and the inactivation of CK in solutions of different concentration of lactic acid were compared. Much lower lactic acid concentration values were required to bring about inactivation than were required to produce significant conformational changes of the enzyme molecule. At higher concentrations of lactic acid (more than 0.2 mM) the CK dimers were partially dissociated, as proved by native polyacrylamide gel electrophoresis. NaCl induced the molten globule state with a compact structure after CK was denatured with 0.8 mM lactic acid, and the increasing of anions led to a tight side-chain. The above results suggest that the effect of lactic acid differed from that of other denaturants such as guanidine hydrochloride, HCl, or urea during CK folding, and the molten globule state indicates that intermediates exist during CK folding.Key words: lactic acid, creatine kinase, salt-induced, unfolding, molten globule state.
Isolation and characterization of a sulfated polysaccharide from the brown algaSargassum patensand determination of its anti-herpes activity
Authors: Zhu Wen , Ooi Vincent E.C , Chan Paul K.S , Ang Jr. Put O
Published: February 2003

Bioactivity-guided fractionation of the hot water extract from the brown alga Sargassum patens led to the isolation of a polysaccharide as an antiviral component against herpes simplex viruses which are the cause of cold sores (HSV-1) and genital herpes (HSV-2). The polysaccharide contained a sulfur group that could be present as a sulfate ester. It is thus a sulfated polysaccharide with a molecular mass of about 424 kDa, and is designated SP-2a. Gas chromatographic assay showed that the polysaccharide consisted of fucose, galactose, mannose, xylose, glucose, and galactosamine. The fucose is the major constituent sugar (35.3%), followed by galactose (18.4%). The 50% effective concentration (EC50) against HSV-2, HSV-1, and HSV-1 acyclovir resistant strain was 1.3, 5.5, and 4.1 µg/mL, respectively. The 50% cytotoxic concentration (CC50) of SP-2a on the growth of normal Vero cell line was more than 4000 µg/mL. Therefore SP-2a of S. patens may be a potent agent for treating HSV infections. Key words: sulfated polysaccharide, anti-herpes activities, brown alga, Sargassum.
Studies on the stability of creatine kinase isozymes
Authors: Guo Zhi , Wang Zheng , Wang Xicheng
Published: February 2003

Research on the stabilizing properties of creatine kinase isozymes CK-BB, CK-MB, and CK-MM showed that minor alteration of their sequence and structure influenced their stability significantly. An analysis of the stability of the isozymes in storage after freeze drying indicates that creatine kinase isozymes are all in monomer form because of the loss of subunit interactions. Freeze-drying leads to the oxidization of CK-BB and rearrangement of CK-MB. There are also differences in the unfolding of the isozymes in urea. CK-BB and CK-MB are unfolded in lower urea concentrations than CK-MM. Differences in the thermal unfolding were also examined by differential scanning calorimetry. This paper discusses the potential biological significance of these results.Key words: creatine kinase isozymes, fluorescence, circular dichroism, differential scanning calorimetry, urea gradient gel electrophoresis.
1,5-isoquinolinediol increases the frequency of gene targeting by homologous recombination in mouse fibroblasts
Authors: Semionov Alexandre , Cournoyer Denis , Chow Terry Y.-K
Published: February 2003

Gene targeting is a technique that allows the introduction of predefined alterations into chromosomal DNA. It involves a homologous recombination reaction between the targeted genomic sequence and an exogenous targeting vector. In theory, gene targeting constitutes the ideal method of gene therapy for single gene disorders. In practice, gene targeting remains extremely inefficient for at least two reasons: very low frequency of homologous recombination in mammalian cells and high proficiency of the mammalian cells to randomly integrate the targeting vector by illegitimate recombination. One known method to improve the efficiency of gene targeting is inhibition of poly(ADP-ribose)polymerase (PARP). It has been shown that PARP inhibitors, such as 3-methoxybenzamide, could lower illegitimate recombination, thus increasing the ratio of gene targeting to random integration. However, the above inhibitors were reported to decrease the absolute frequency of gene targeting. Here we show that treatment of mouse Ltk cells with 1,5-isoquinolinediol, a recent generation PARP inhibitor, leads to an increase up to 8-fold in the absolute frequency of gene targeting in the correction of the mutation at the stable integrated HSV tk gene.Key words: DNA recombination, gene targeting, PARP inhibition.
Palmitic acid incorporation into intramuscular acylglycerols depends on both total and unbound to albumin palmitic acid concentration
Authors: Synak M , Górecka M , Langfort J , Smol E , Zernicka E
Published: February 2003

Palmitic acid incorporation into the intramuscular acylglycerols in rat skeletal muscles of different fiber types was investigated at various total and unbound to albumin concentrations by means of the hind-limb perfusion technique. It was found that at simultaneously increasing total and unbound to albumin palmitic acid concentrations in the perfusion medium the incorporation of palmitic acid into acylglycerols increased. However, when the concentration of palmitic acid not bound to albumin was kept constant and the total palmitic acid concentration was increased, the incorporation also increased although markedly less than under former conditions. The increase was most apparent in the muscles composed of slow-twitch oxidative and fast-twitch oxidative-glycolytic fibers where fatty acid uptake is the greatest. These findings suggest that fatty acid incorporation into intramuscular acylglycerols depends not only on the unbound to albumin fatty acid concentration but also, to some extent, on the total fatty acid concentration.Key words: skeletal muscle, perfusion, fatty acid uptake.
Amyloid insulin interaction with erythrocytes
Authors: Murali J , Koteeswari D , Rifkind J M , Jayakumar R
Published: February 2003

Erythrocyte membrane interactions with insulin fibrils (amyloid) have been investigated using centrifugation, fluorescence spectroscopy, light scattering, and flow cytometric techniques. The results indicate that insulin fibrils are having moderate affinity to erythrocyte membrane. However, analysis of the apparent dissociation constants of human erythrocyte membranes (leaky and resealed vesicles) with amyloid insulin reveal that the insulin binding is drastically reduced on attaining the fibrillar state compared with native insulin. To understand the role of insulin receptors on erythrocytes binding to amyloid, we have studied the interaction of biotinylated forms of denatured and amyloidic insulin with erythrocytes. FITC-streptavidin was used as a counter staining in flow cytometry measurements. We found that insulin fibrils bind 10 times more with erythrocyte membranes than with amylin and denatured insulin.Key words: insulin amyloid, erythrocyte membrane, amyloid binding, flow cytometry, dissociation constant.
Polymorphic mutations of the Mn-SOD gene in intact human lymphocytes and oral squamous cell carcinoma cell lines
Authors: Kamatani Takaaki , Yamamoto Tetsuya , Yoneda Kazunori , Osaki Tokio
Published: February 2003

Mutations of the superoxide dismutase (SOD) genes are associated with neoplastic and non-neoplastic diseases. However, the existence of polymorphic mutations of manganese SOD (Mn-SOD) has not been explored in squamous cell carcinoma (SCC) cells or in normal cells. In the present study, we examined mutations in the 5' flanking region of the Mn-SOD gene and Mn-SOD mRNA using 10 human oral SCC (OSC) cell lines and intact lymphocytes obtained from 10 healthy donors and one patient with OSC. The polymerase chain reaction products of DNA obtained from lymphocytes revealed insertions at many sites (1833, 1575, 1093, 1056, 325, 318, and 310) in 10 of the 11 donors. Transitions and (or) transversions were also observed at 1638 and 216 in lymphocytes from six donors and one donor, respectively. In DNA obtained from OSC cells, insertions and transitions and (or) transversions were more frequent than those in DNA from lymphocytes. In addition, deletions at 1341 and 1288 were observed in all lines except for one line. In these mutations, the transcription factor binding sites were not involved except for the AP-2 binding site (102) in three cell lines. In Mn-SOD mRNA, Val at 9 position was varied to Ala in lymphocytes from two donors and three OSC cell lines, respectively. In the remaining cell lines, Mn-SOD mRNA from lymphocytes and OSC cell lines revealed heterozygosity (Ala/Val) and homozygosity (Val/Val), respectively. The Mn-SOD activities in lymphocytes were 3.85.8 × 104U/106cells and the activities in OSC cell lines were 1.88.3 × 104U/106cells. These Mn-SOD activities were not correlated with the mutations of DNA and mRNA. From these results, it is indicated that polymorphic mutations of Mn-SOD exist in human normal cells and that the deletions might be obtained in the course of malignant transformation of OSC although decrease in Mn-SOD activity is not involved in the transformation.Key words: Mn-SOD, gene mutations, squamous cell carcinoma cells, lymphocytes.
NUMERICAL APPROACH TO FOKKER–PLANCK EQUATIONS FOR BROWNIAN MOTORS
Authors: KOSTUR MARCIN
Published: February 2003

The numerical approach to a large class of one- and two-dimensional Fokker–Planck equations (FPE) often encountered in modeling Brownian Motors is presented. The method is based on Finite Element scheme with additional modifications for specific problems. We compare results from discretization of FPE with those obtained from Monte Carlo (MC) simulation of the corresponding Langevin equations. Accuracy, efficiency and applicability are also discussed.
INTEGRATION OF STOCHASTIC DIFFERENTIAL EQUATIONS ON A COMPUTER
Authors: MANNELLA RICCARDO
Published: February 2003

A brief introduction to the simulation of stochastic differential equations is presented. Algorithms to simulate rare fluctuations, a topic of interest in the light of recent theoretical work on optimal paths are studied. Problems connected to the treatment of the boundaries and correlated noise will also be discussed.
A TRIO OF BROWNIAN DONKEYS
Authors: VAN DEN BROECK C. , CLEUREN B. , KAWAI R. , KAMBON M.
Published: February 2003

A previously introduced model (B. Cleuren and C. Van den Broeck, Europhys. Lett.54, 1 (2001)) is studied numerically. Pure negative mobility is found for the minimum number of three interacting walkers.
COLLECTIVE ROTATION IN COUPLED PARAMETRICALLY-DRIVEN PENDULUMS
Authors: KAWAI RYOICHI , WILLIAMS NATHAN , RAST LAUREN
Published: February 2003

Collective instabilities in globally coupled pendulums driven by parametric modulation is numerically investigated. Parametric instabilities are suppressed by mutual synchronization despite individual pendulums are under a parametric resonance condition. On the other hand, continuous collective rotation can be parametrically excited with certain modulation frequencies outside the regular parametric resonance.
IMPLICATION OF BARRIER FLUCTUATIONS ON THE RATE OF WEAKLY ADIABATIC ELECTRON TRANSFER
Authors: DYBIEC BARTŁOMIEJ , GUDOWSKA-NOWAK EWA , GÓRA PAWEŁ F.
Published: February 2003

The problem of escape of a Brownian particle in a cusp-shaped metastable potential is of special importance in nonadiabatic and weakly-adiabatic rate theory for electron transfer (ET) reactions. For the weakly-adiabatic reactions, the reaction follows an adiabaticity criterion in the presence of a sharp barrier. In contrast to the nonadiabatic case, the ET kinetics can be, however considerably influenced by the medium dynamics. In this paper, the problem of the escape time over a dichotomously fluctuating cusp barrier is discussed with its relevance to the high temperature ET reactions in condensed media.
THE RANGE OF THE CONTACT INTERACTIONS AND THE KINETICS OF THE GO MODELS OF PROTEINS
Authors: CIEPLAK MAREK , HOANG TRINH XUAN
Published: February 2003

We consider two types of Go models of a protein (crambin) and study their kinetics through molecular dynamics simulations. In the first model, the residue–residue contact interactions are selected based on a cutoff distance, Rc. The folding times strongly depend on the value of Rc and nonmonotonically. This indicates a need for a physically determined set of native contacts. One may accomplish it by considering the van der Waals radii of the residual atoms and checking if the atoms overlap. In the second model, non-native attractive contacts are added to the system. This leads to bad foldability. However, for a small number of such extra contacts there is a slight acceleration in the kinetics of folding.
WAVE PATTERN DYNAMICS IN FLUCTUATING MEDIA
Authors: SAGUÉS F. , ALONSO S. , SANCHO J. M.
Published: February 2003

Analytical and numerical results on the ordering role of external random fluctuations in excitable systems are presented. Our study focuses on a simple model for excitable systems. Regular waves are created and sustained out of noise when the system is forced with random perturbations. Explicit results for the generation and dynamics of rings and targets are presented.
NONEQUILIBRIUM SPATIAL CORRELATIONS IN CHEMICAL SYSTEMS: BEYOND ORNSTEIN–ZERNIKE
Authors: WAKOU JUNICHI , KITAHARA KAZUO , LITNIEWSKI MAREK , GORECKI JERZY
Published: February 2003

In this paper we consider a chemical process, for which the reagent of interest decays shortly after it is created. For such a system the standard theory of nonequilibrium spatial correlations in the density fluctuations, which leads to Ornstein–Zernike type of expression, does not work. We compare results of molecular simulations with another theoretical description based on the assumption that the lifetime of the reagent is short enough to treat its motion as a ballistic rather than diffusive one.
VIOLATION OF MOLECULAR CHAOS IN DISSIPATIVE GASES
Authors: PÖSCHEL THORSTEN , BRILLIANTOV NIKOLAI V. , SCHWAGER THOMAS
Published: February 2003

Numerical simulations of a dissipative hard sphere gas reveal a dependence of the cooling rate on correlation of the particle velocities due to inelastic collisions. We propose a coefficient which characterizes the velocity correlations in the two-particle velocity distribution function and express the temperature decay rate in terms of this coefficient. The analytical results are compared with numerics.
NONCANONICAL POISSON BRACKETS AND HAMILTONIAN EVOLUTION EQUATIONS FOR NONEQUILIBRIUM MOLECULAR DYNAMICS SIMULATIONS
Authors: DRESSLER MARCO , EDWARDS BRIAN J.
Published: February 2003

Nonequilibrium molecular dynamics (NEMD) simulations of fluids are generally based on either a DOLLS or SLLOD tensor algorithm. The former is always considered to be a Hamiltonian system, but not particularly useful in high strain rate flow simulations, while the latter is not considered to be a Hamiltonian system, but much more practical and accurate in flow simulations. We demonstrate herein using noncanonical transformations of the particle momenta of the system that the SLLOD equations, when written in terms of appropriate noncanonical variables, are completely Hamiltonian, whereas the DOLLS equations are not so. A modified set of DOLLS equations in terms of the noncanonical variables which again is completely Hamiltonian is also derived. Both algorithms then lead to a phase space distribution function which is canonical in both the coordinates and momenta.
CURVATURE EFFECTS IN CLUSTERS GROWN IN A 2D DISCRETE SPACE: AN ALGEBRAIC APPROACH
Authors: GADOMSKI ADAM
Published: February 2003

According to a phenomenological phase transition mechanism introduced quite recently, we propose a systematic examination of the polymorphic contraction–expansion effects observed for a broad class of morphologies with nonvanishing surface (line) tension. In our mean-field approach, we are looking for the line order parameter behavior as a function of a thermodynamic control parameter at a fixed number of entities consituting the morphology as a whole. We also wish to somehow invert the problem, and will be looking for some evolution going via a set of quasi-equilibrium states while fixing the control parameter. Both the situations considered are of interest for studying the so-called morphology diagrams as well as, to some extent, for describing selected model evolutions in a two-dimensional microworld, e.g., in nanoscale, where biomembranes and interfaces are presently of special attention.
MODELING OF GOLD DISPERSION IN GLASSY POLYMERS BY SMOLUCHOWSKI EQUATION
Authors: GRZYWNA ZBIGNIEW J. , STOLARCZYK JACEK
Published: February 2003

A unidimensional diffusion in a potential field of induced stress is considered. The way from random walk (RW) to limiting partial differential equation (Smoluchowski equation) for standard and time dependent RW is shown. A technologically important case of gold dispersion in crystallizing polymer swollen by acetone vapor is analyzed. Theoretical predictions based on Smoluchowski equation with time dependent coefficients are found to be in very good agreement with experimental data.
DETERMINISTIC RATCHETS: FROM CONFINED TO DIFFUSIVE CHAOS
Authors: BORROMEO M. , MARCHESONI F.
Published: February 2003

An AC driven, noiseless, underdamped Brownian particle moving on an asymmetric periodic substrate provides an interesting example of deterministic ratchet: In the adiabatic regime periodic and chaotic trajectories coexist on fine tuning the amplitude of the input signal; the transition from regular to chaotic transport happens through an intermediate class of trajectories exhibiting confined chaos.
PARALLEL DISTRIBUTED SOLVERS FOR LARGE STABLE GENERALIZED LYAPUNOV EQUATIONS
Authors: BENNER PETER , CLAVER JOSÉ M. , QUINTANA-ORTI ENRIQUE S.
Published: February 2003

In this paper we study the solution of stable generalized Lyapunov matrix equations with large-scale, dense coefficient matrices. Our iterative algorithms, based on the matrix sign function, only require scalable matrix algebra kernels which are highly efficient on parallel distributed architectures. This approach avoids therefore the difficult parallelization of direct methods based on the QZ algorithm. The experimental analtsis reports a remarkable performance of our solvers on an IBM SP2 platform.
FAST DETERMINISTIC PARALLEL BRANCH-AND-BOUND
Authors: HERLEY KIERAN T. , PIETRACAPRINA ANDREA , PUCCI GEPPINO
Published: February 2003

The branch-and-bound problem involves determining the minimum cost leaf in a cost-labelled tree, subject to the constraint that only the root is known initially and that children are revealed only by visiting thier parent. We present the first efficient deterministic algorithm to solve the branch-and-bound problem for a tree T of constant degree on a p-processor parallel machine. Let c* be the cost of the minimum-cost leaf in T, and let n and h be the number of nodes and the height, respectively, of the subtree T* ⊆ T of nodes of cost less than or equal to c*. Our algorithm runs in O(n/p + h log 2(np)) time on an EREW-PRAM. Moreover, the running time faithfully reflects both communication and computation costs, unlike most of the previous results where the cost of local computation is ignored. For large ranges of the parameters, our algorithm matches the optimal performance of existing randomized strategies. The algorithm can be ported to any architecture for which an efficient implementation of Parallel Priority Queues [PP91] is available.
MINIMIZING THE DIAMETER IN TREE NETWORKS UNDER EDGE REDUCTIONS
Authors: HAMBRUSCH SUSANNE E. , LIM HYEONG-SEOK
Published: February 2003

Edge reductions model the ability of speeding up communication between processors in a network. In this paper we consider performing edge reductions in a tree network so that the diameter of the tree is minimized. The diameter is directly related to the time needed to broadcast a message. In particular, for non-blocking message communication ignoring start-up costs, the diameter corresponds to the broadcasting time. For an n-vertex tree T and a quantity B, we present an O(n) time algorithm to determine edge reductions such that the resulting tree has diameter at most B and the cost of the reduction is a minimum (over all reductions resulting in a diameter of at most B).
A RANDOMIZED BSP/CGM ALGORITHM FOR THE MAXIMAL INDEPENDENT SET PROBLEM
Authors: FERREIRA AFONSO , SCHABANEL NICOLAS
Published: February 2003

This paper presents a randomized parallel algorithm for the Maximal Independent Set problem. Our algorithm uses a BSPlike computer with p processors and requires that [Formula: see text] for a graph with n vertices and m edges. Under this scalability assumption, and after a preprocessing phase, it computes a maximal independent set after O( log p) communication rounds, with high probability, each round requiring linear computation time [Formula: see text]. The preprocessing phase is deterministic and important in order to ensure that degree computations can be implemented efficiently. For this, we give an optimal parallel BSPCGM algorithm to the p-quantiles search problem, which runs in [Formula: see text] time and a constant number of communication rounds, and could be of interest in its own right, as shown in the text.
PHOTOLUMINESCENCE FROM SILICON NANO-PARTICLES SYNTHESIZED BY PULSED LASER ABLATION
Authors: NARAYANAN V. , THAREJA R. K.
Published: February 2003

We report on the synthesis and characterization of silicon nanoparticles by ablating silicon wafer in an ambient atmosphere of helium at 1 Torr. The mean cluster size ranging from 1.8 nm to 4.4 nm deposited on silicon substrate at room temperature is observed to depend on the laser fluence. The size of the nanoparticles decreases with laser fluence. Photoluminescence of the deposited films using Nd:YAG laser and Ar + ion laser at 355 nm and 457.9 nm respectively shows emission peaks at 1.7, 2.2, and 2.7 eV. The luminescence peak at 2.2 eV and 2.7 eV are attributed to oxygen related impurities and the peak at 1.7 eV is attributed to quantum confinement.
NEW DNLS EQUATIONS FOR ANHARMONIC VIBRATIONAL IMPURITIES
Authors: MOLINA M. I.
Published: February 2003

We examine some new DNLS-like equations that arise when considering strongly-coupled electron-vibration systems, where the local oscillator potential is anharmonic. In particular, we focus on a single, rather general nonlinear vibrational impurity and determine its bound state(s) and its dynamical selftrapping properties.
PROKARYOTIC PHYLOGENY BASED ON COMPLETE GENOMES WITHOUT SEQUENCE ALIGNMENT
Authors: HAO BAILIN , QI JI , WANG BIN
Published: February 2003

We present a brief review of a series of on-going work on bacterial phylogeny. We propose a new method to infer relatedness of prokaryotes from their complete genome data without using sequence alignment, leading to results comparable with the bacteriologist's systematics as reflected in the latest 2001 edition of Bergey's Manual of Systematic Bacteriology.1 We only touch on the mathematical aspects of the method. The biological implications of our results will be published elsewhere.