bluuebunny/crossref_metadata_2025 huggingface dataset:
Lentivirus Infection in the Brain Induces Matrix Metalloproteinase Expression: Role of Envelope Diversity
Authors: Johnston J. B. , Jiang Y. , van Marle G. , Mayne M. B. , Ni W. , Holden J. , McArthur J. C. , Power C.
Published: July 2002

Infection of the brain by lentiviruses, including human immunodeficiency virus (HIV) and feline immunodeficiency virus (FIV), causes inflammation and results in neurodegeneration. Molecular diversity within the lentivirus envelope gene has been implicated in the regulation of cell tropism and the host response to infection. Here, we examine the hypothesis that envelope sequence diversity modulates the expression of host molecules implicated in lentivirus-induced brain disease, including matrix metalloproteinases (MMP) and related transcription factors. Infection of primary macrophages by chimeric HIV clones containing brain-derived envelope fragments from patients with HIV-associated dementia (HAD) or nondemented AIDS patients (HIV-ND) showed that MMP-2 and -9 levels in conditioned media were significantly higher for the HAD clones. Similarly, STAT-1 and JAK-1 levels were higher in macrophages infected by HAD clones. Infections of primary feline macrophages by the neurovirulent FIV strain (V1CSF), the less neurovirulent strain (Petaluma), and a chimera containing the V1CSF envelope in a Petaluma background (FIV-Ch) revealed that MMP-2 and -9 levels were significantly higher in conditioned media from V1CSF- and FIV-Ch-infected macrophages, which was associated with increased intracellular STAT-1 and JAK-1 levels. The STAT-1 inhibitor fludarabine significantly reduced MMP-2 expression, but not MMP-9 expression, in FIV-infected macrophages. Analysis of MMP mRNA and protein levels in brain samples from HIV-infected persons or FIV-infected cats showed that MMP-2 and -9 levels were significantly increased in lentivirus-infected brains compared to those of uninfected controls. Elevated MMP expression was accompanied by significant increases in STAT-1 and JAK-1 mRNA and protein levels in the same brain samples. The present findings indicate that two lentiviruses, HIV and FIV, have common mechanisms of MMP-2 and -9 induction, which is modulated in part by envelope sequence diversity and the STAT-1/JAK-1 signaling pathway.
Transgenic or Plant Expression Vector-Mediated Recombination ofPlum Pox Virus
Authors: Varrelmann Mark , Palkovics Laszlo , Maiss Edgar
Published: July 2002

Different mutants of an infectious full-length clone (p35PPV-NAT) ofPlum pox virus(PPV) were constructed: three mutants with mutations of the assembly motifs RQ and DF in the coat protein gene (CP) and two CP chimeras with exchanges in the CP core region ofZucchini yellow mosaic virusandPotato virus Y. The assembly mutants were restricted to single infected cells, whereas the PPV chimeras were able to produce systemic infections inNicotiana benthamianaplants. After passages in different transgenicN. benthamianaplants expressing the PPV CP gene with a complete (plant line 4.30.45.) or partially deleted 3′-nontranslated region (3′-NTR) (plant line 17.27.4.), characterization of the viral progeny of all mutants revealed restoration of wild-type virus by recombination with the transgenic CP RNA only in the presence of the complete 3′-NTR (4.30.45.). Reconstitution of wild-type virus was also observed following cobombardment of different assembly-defective p35PPV-NAT together with a movement-defective plant expression vector ofPotato virus Xexpressing the intact PPV-NAT CP gene transiently in nontransgenicN. benthamianaplants. Finally, a chimeric recombinant virus was detected after cobombardment of defective p35PPV-NAT with a plant expression vector-derived CP gene from the sour cherry isolate of PPV (PPV-SoC). This chimeric virus has been established by a double recombination event between the CP-defective PPV mutant and the intact PPV-SoC CP gene. These results demonstrate that viral sequences can be tested for recombination events without the necessity for producing transgenic plants.
Clink, a Nanovirus-Encoded Protein, Binds both pRB and SKP1
Authors: Aronson Marie N. , Meyer Alain D. , Györgyey Jànos , Katul Lina , Vetten H. Josef , Gronenborn Bruno , Timchenko Tatiana
Published: July 2002

Clink, a 20-kDa protein of faba bean necrotic yellows virus, a single-stranded DNA plant virus, interacts with pRB family members and a SKP1 homologue from
Medicago sativa
. An LxCxE motif and an F-box of Clink mediate the interactions with the respective proteins. The capacity of Clink to bind pRB correlates with its ability to stimulate viral replication. Interaction of a single protein with the cell cycle regulator pRB and SKP1, a constituent of the ubiquitin-protein turnover pathway, appears to be a novel feature. Hence, Clink may represent a new class of viral cell cycle modulators.
Biochemical Characterization of the Helper Component of
Cauliflower Mosaic Virus
Authors: Hebrard Eugenie , Drucker Martin , Leclerc Denis , Hohn Thomas , Uzest Marilyne , Froissart Remy , Strub Jean-Marc , Sanglier Sarah , van Dorsselaer Alain , Padilla Andre , Labesse Gilles , Blanc Stephane
Published: July 2002

The helper component of
Cauliflower mosaic virus
is encoded by viral gene II. This protein (P2) is dispensable for virus replication but required for aphid transmission. The purification of P2 has never been reported, and hence its biochemical properties are largely unknown. We produced the P2 protein via a recombinant baculovirus with a His tag fused at the N terminus. The fusion protein was purified by affinity chromatography in a soluble and biologically active form. Matrix-assisted laser desorption time-of-flight mass spectrometry demonstrated that P2 is not posttranslationally modified. UV circular dichroism revealed the secondary structure of P2 to be 23% α-helical. Most α-helices are suggested to be located in the C-terminal domain. Using size exclusion chromatography and aphid transmission testing, we established that the active form of P2 assembles as a huge soluble oligomer containing 200 to 300 subunits. We further showed that P2 can also polymerize as long paracrystalline filaments. We mapped P2 domains involved in P2 self-interaction, presumably through coiled-coil structures, one of which is proposed to form a parallel trimer. These regions have previously been reported to also interact with viral P3, another protein involved in aphid transmission. Possible interference between the two types of interaction is discussed with regard to the biological activity of P2.
Ty1 Proteolytic Cleavage Sites Are Required for Transposition: All Sites Are Not Created Equal
Authors: Merkulov Gennady V. , Lawler Joseph F. , Eby Yolanda , Boeke Jef D.
Published: July 2002

The retroviral protease is a key enzyme in a viral multienzyme complex that initiates an ordered sequence of events leading to virus assembly and propagation. Viral peptides are initially synthesized as polyprotein precursors; these precursors undergo a number of proteolytic cleavages executed by the protease in a specific and presumably ordered manner. To determine the role of individual protease cleavage sites in Ty1, a retrotransposon from
Saccharomyces cerevisiae
, the cleavage sites were systematically mutagenized. Altering the cleavage sites of the yeast Ty1 retrotransposon produces mutants with distinct retrotransposition phenotypes. Blocking the Gag/PR site also blocks cleavage at the other two cleavage sites, PR/IN and IN/RT. In contrast, mutational block of the PR/IN or IN/RT sites does not prevent cleavage at the other two sites. Retrotransposons with mutations in each of these sites have transposition defects. Mutations in the PR/IN and IN/RT sites, but not in the Gag/PR site, can be complemented in
trans
by endogenous Ty1 copies. Hence, the digestion of the Gag/PR site and release of the protease N terminus is a prerequisite for processing at the remaining sites; cleavage of PR/IN is not required for the cleavage of IN/RT, and vice versa. Of the three cleavage sites in the Gag-Pol precursor, the Gag/PR site is processed first. Thus, Ty1 Gag-Pol processing proceeds by an ordered pathway.
Neutralization of Hepatitis A Virus (HAV) by an Immunoadhesin Containing the Cysteine-Rich Region of HAV Cellular Receptor-1
Authors: Silberstein Erica , Dveksler Gabriela , Kaplan Gerardo G.
Published: July 2002

Hepatitis A virus (HAV) infects African green monkey kidney (AGMK) cells via the HAV cellular receptor-1 (havcr-1), a mucin-like type 1 integral-membrane glycoprotein of unknown natural function. The ectodomain of havcr-1 contains an N-terminal immunoglobulin-like cysteine-rich region (D1), which binds protective monoclonal antibody (MAb) 190/4, followed by an O-glycosylated mucin-like threonine-serine-proline-rich region that extends D1 well above the cell surface. To study the interaction of HAV with havcr-1, we constructed immunoadhesins fusing the hinge and Fc portion of human IgG1 to D1 (D1-Fc) or the ectodomain of the poliovirus receptor (PVR-Fc) and expressed them in CHO cells. These immunoadhesins were secreted to the cell culture medium and purified through protein A-agarose columns. In a solid-phase assay, HAV bound to D1-Fc in a concentration-dependent manner whereas background levels of HAV bound to PVR-Fc. Binding of HAV to D1-Fc was blocked by treatment with MAb 190/4 but not with control MAb M2, which binds to a tag epitope introduced between the D1 and Fc portions of the immunoadhesin. D1-Fc neutralized approximately 1 log unit of the HAV infectivity in AGMK cells, whereas PVR-Fc had no effect in the HAV titers. A similarly poor reduction in HAV titers was observed after treating the same stock of HAV with murine neutralizing MAbs K2-4F2, K3-4C8, and VHA 813. Neutralization of poliovirus by PVR-Fc but not by D1-Fc indicated that the virus-receptor interactions were specific. These results show that D1 is sufficient for binding and neutralization of HAV and provide further evidence that havcr-1 is a functional cellular receptor for HAV.
Chromosomal Integration of Transduced Recombinant Baculovirus DNA in Mammalian Cells
Authors: Merrihew Raymond V. , Clay William C. , Condreay J. Patrick , Witherspoon Sam M. , Dallas Walter S. , Kost Thomas A.
Published: July 2002

Our group and others have recently demonstrated the ability of recombinant baculoviruses to transduce mammalian cells at high frequency. To further characterize the use of baculovirus as a mammalian gene delivery system, we examined the status of transduced DNA stably maintained in Chinese hamster ovary (CHO) cells. Four independent clones carrying two introduced markers, the genes for neomycin resistance (Neo) and green fluorescent protein (GFP), were selected. PCR analysis, Southern blotting, and DNA sequencing showed that discrete portions of the 148-kb baculovirus DNA were present as single-copy fragments ranging in size from 5 to 18 kb. Integration into the CHO cell genome was confirmed by fluorescent in situ hybridization (FISH) analysis. For one clone, the left and right viral/chromosomal junctions were determined by DNA sequencing of inverse PCR products. Similarly, for a different clone, the left viral/chromosomal junction was determined; however, the right junction sequence revealed the joining to another viral fragment by a short homology (microhomology), a hallmark of illegitimate recombination. The random viral breakpoints and the lack of homology between the virus and flanking chromosomal sequences are also suggestive of an illegitimate integration mechanism. To examine the long-term stability of reporter gene expression, all four clones were grown continuously for 36 passages in either the presence or absence of selection for Neo. Periodic assays over a 5-month period showed no loss of GFP expression for at least two of the clones. This report represents the first detailed analysis of baculovirus integrants within mammalian cells. The potential advantages of the baculovirus system for the stable integration of genetic material into mammalian genomes are discussed.
Function of the Intercistronic Region of BRLF1-BZLF1 Bicistronic mRNA in Translating the Zta Protein of Epstein-Barr Virus
Authors: Chang Pey-Jium , Liu Shih-Tung
Published: July 2002

Zta, a transcription factor encoded by Epstein-Barr virus, is efficiently translated from a BRLF1-BZLF1 bicistronic mRNA. In this study, we demonstrate that inserting a stem-loop structure, which is known to block ribosome scanning, in the 5′ region of the intercistronic region does not prevent the translation of a luciferase reporter protein from the bicistronic mRNA fused with the firefly luciferase gene, suggesting that the translation does not involve translation reinitiation. Mutational analyses reveal that the region between nucleotides 86 and 125 (region I) of the intercistronic region is essential for the translation. Meanwhile, the region between nucleotides 126 and 165 (region II) is also important since, without this region, the translation is inefficient. The region I sequence is partially complementary to the sequence between nucleotides 1489 and 1524 of 18S rRNA. This homology is significant, since disrupting the homology reduces the translation efficiency. Furthermore, luciferase is efficiently translated if the entire intercistronic region is replaced with a sequence complementary to the region between nucleotides 1401 and 1560 of the 18S rRNA. We hypothesize that Rta may assist 40S ribosome in recognizing the region I sequence to start a scanning process for Zta translation.
Furin Is Involved in Baculovirus Envelope Fusion Protein Activation
Authors: Westenberg Marcel , Wang Hualin , IJkel Wilfred F. J. , Goldbach Rob W. , Vlak Just M. , Zuidema Douwe
Published: July 2002

The
Spodoptera exigua
multicapsid nucleopolyhedrovirus (Se
M
NPV)
Se8
gene was recently shown to encode the viral envelope fusion (F) protein. A 60-kDa C-terminal subunit (F
1
) of the 76-kDa primary translation product of this gene was found to be the major envelope protein of Se
M
NPV budded virus (BV) (W. F. J. IJkel, M. Westenberg, R. W. Goldbach, G. W. Blissard, J. M. Vlak, and D. Zuidema, Virology 275:30–41, 2000). A specific inhibitor was used to show that furin is involved in cleavage of the precursor envelope fusion (F
0
) protein. BV produced in the presence of the inhibitor possesses the uncleaved F
0
protein, while an F protein with a mutation in the furin cleavage site was translocated to the plasma membrane but lost its fusogenic activity. These results indicate that cleavage of F
0
is required to activate the Se
M
NPV F protein and is necessary for BV infectivity. Specific antibodies against F
1
and against the putative N terminus (F
2
) of the primary translation product were used to show that the F protein is BV specific and that BVs contain both the 60- (F
1
) and 21-kDa (F
2
) cleavage products. In nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis both subunits migrate as a single 80-kDa protein, indicating that the subunits remain associated by a disulfide linkage. In addition, the presence of the F protein predominately as a monomer suggests that disulfide links are not involved in oligomerization. Thus, the envelope fusion protein from group II nucleopolyhedroviruses of baculoviruses has properties similar to those of proteins from a number of vertebrate viruses.
Longitudinal Analysis of Feline Leukemia Virus-Specific Cytotoxic T Lymphocytes: Correlation with Recovery from Infection
Authors: Flynn J. Norman , Dunham Stephen P. , Watson Vivien , Jarrett Oswald
Published: July 2002

Feline leukemia virus (FeLV) is a common naturally occurring gammaretrovirus of domestic cats that is associated with degenerative diseases of the hematopoietic system, immunodeficiency, and neoplasia. Although the majority of cats exposed to FeLV develop a transient infection and recover, a proportion of cats become persistently viremic and many subsequently develop fatal diseases. To define the dominant host immune effector mechanisms responsible for the outcome of infection, we studied the longitudinal changes in FeLV-specific cytotoxic T lymphocytes (CTLs) in a group of na|$$|Ad|five cats following oronasal exposure to FeLV. Using51Cr release assays to measure ex vivo virus-specific cytotoxicity, the emerging virus-specific CTL response was correlated with modulations in viral burden as assessed by detection of infectious virus, FeLV p27 capsid antigen, and proviral DNA in the blood. High levels of circulating FeLV-specific effector CTLs appeared before virus neutralizing antibodies in cats that recovered from exposure to FeLV. In contrast, persistent viremia was associated with a silencing of virus-specific humoral and cell-mediated host immune effector mechanisms. A single transfer of between 2 × 107and 1 × 108autologous, antigen-activated lymphoblasts was associated with a downmodulation in viral burden in vivo. The results suggest an important role for FeLV-specific CTLs in retroviral immunity and demonstrate the potential to modulate disease outcome by the adoptive transfer of antigen-specific T cells in vivo.
Photocatalytic Effect of Fe(III) on Oxidation of Two-Carbon Substrates Related to Natural Waters
Authors: Klementová Šárka , Wagnerová Dana M.
Published: July 2002

The influence of ferric ions on photoinitiated reaction of dioxygen with two carbon organic acids, aldehydes and alcohols related to natural waters was demonstrated. Photocatalytic effect of ferric ions, i.e. photochemical reduction of Fe(III) as the catalyst generating step, has been found to be the common principal of these reactions. The overall quantum yields of the reactions are in the range from 0.3 to 1.2. A mathematical model designed for the mechanism of cyclic generation of catalyst in the singlet substrate oxidation by O2 was applied to the system glyoxalic acid + Fe(III); a fair agreement between the simulated and experimental kinetic curves was obtained. The experimental rate constant is 4.4 .10-4 s -1.
Application of Monoalkyl Methanephosphonates to Extraction of Selected Metals
Authors: Tokárová Alena , Navrátil Oldřich , Sládek Petr
Published: July 2002

The distribution of scandium and hafnium between 0.1 or 1.0 mol l-1 HNO3 and solutions of monoalkyl methanephosphonates (HA; alkyl = methyl, propyl, butyl, isobutyl, pentyl, 2-methylbutyl, cyclohexyl, 1,2,2-trimethylpropyl) in chloroform and 1,1,2,2-tetrachloroethane has been studied. The organic solvents mentioned allow to obtain the optimum values of partition coefficients of the two metals. The corresponding extraction constants of the ScA3(HA)x and Hf(NO3)4(HA)4 complexes have been calculated.
Kinetics of Formation of Peroxyformic Acid
Authors: Mošovský Vladimír , Cvengrošová Zuzana , Kaszonyi Alexander , Králik Milan , Hronec Milan
Published: July 2002

Oxidation kinetics of formic acid with aqueous hydrogen peroxide (30-70%) has been studied at 45 °C with 0-0.1 M H2SO4 as a catalyst. A kinetic model has been suggested which satisfactorily describes the oxidation process of formic acid to peroxyformic acid.
Preparation and Reactions of 2-Chloroethyl 1-Thio-β-D-glycopyranosides Derived from D-Galactose, D-Glucose, and 2-Acetamido-2-deoxy-D-glucose
Authors: Černý Miloslav , Trnka Tomáš , Buděšínský Miloš
Published: July 2002

Chloroethyl 1-thio-β-D-glycopyranosides of the D-galacto and D-gluco configurations 5a-5c were prepared by alkylation of the corresponding 1-thio-β-D-hexopyranoses 3a-3c with 1-bromo-2-chloroethane followed by deacetylation. The starting 1-thio-β-D-hexopyranoses were obtained from the acetylated glycopyranosyl halides via isothiouronium salts. It was demonstrated that the chloroethyl thioglycosides 5a-5c undergo hydrolysis in aqueous solutions to give the 2-hydroxyethyl thioglycosides 6a-6c and reducing hexoses and that this hydrolysis proceeds via episulfonium salts. The hydrolysis was monitored by 1H and 13C NMR spectroscopy. In 1% aqueous solutions of sodium carbonate containing phenol or aniline, the thioglycosides 5a-5c provide, in addition to the above hydrolysis products, also the phenoxyethyl and phenylaminoethyl thioglycosides 9a, 10a and 9b, 10b, respectively.
Dynamics of Electrodiffusion Friction Probes. I. Shape-Dependent Potentiostatic Transient
Authors: Wein Ondřej , Sobolík Václav
Published: July 2002

An exact theory is given of the voltage-step transient under limiting diffusion conditions for an electrodiffusion friction probe of arbitrary convex shape. The actual transient courses are given for the strip, circular, elliptic, triangular, and rectangular probes of any orientation with respect to the flow direction. A simple formula for any probe with a single working electrode of convex shape is suggested to facilitate the calibration of electrodiffusion probes based on the voltage-step transient.
Steady-State and Dynamic Mass Transfer of Gases in Porous Materials
Authors: Tuchlenski Axel , Schramm Oliver , Seidel-Morgenstern Andreas
Published: July 2002

The diffusion of binary gas mixtures through a porous asymmetric tubular membrane has been studied experimentally. A modified Wicke-Kallenbach diffusion cell consisting of two gas compartments separated by the membrane was used. Steady-state experiments with pure gases and binary mixtures were carried out in order to determine the transport parameters of the membrane with respect to the dusty gas model. To verify these parameters, the dynamic transport of binary mixtures was examined applying the dynamic diffusion cell technique proposed by Novak et al. The measured transients were in relative good agreement with the model predictions.
Spirocyclization of Isatin with Chiral α-Aminothiols: Diastereoselective Synthesis of (-)- and (+)-4'-(Methoxycarbonyl)spiro[indoline-3,2'-thiazolidin]-2-one
Authors: Kutschy Peter , Suchý Mojmír , Dzurilla Milan , Pazdera Pavel , Takasugi Mitsuo , Kováčik Vladimír
Published: July 2002

Reactions of isatin with chiral α-aminothiols have been studied. With L-cysteine, only decomposition products were formed under various reaction conditions, whereas D- and L-penicillamine afforded mixtures of diastereomeric 4'-carboxy-5',5'-dimethylspiro[indoline- 3,2'-thiazolidin]-2-ones (4a and 4b or 5a and 5b) in the ratio 1 : 1. The reaction of isatin with methyl L- and D-cysteinates under mild reaction conditions (methanol-benzene, room temperature) proceeded diastereoselectively with the formation of (-)- and (+)-4'-(methoxycarbonyl)spiro[indoline-3,2'-thiazolidin]-2-one (6a and 8) in 38 and 30% yields, respectively. Optically inactive 4'-(methoxycarbonyl)spiro[indoline-3,2'-([2',5']dihydrothiazol)]-2-one (7) was isolated as a side product in 7 and 3% yield, respectively. Structure of the obtained products was determined by spectral methods, including NOE difference measurements and by X-ray crystallography.
Tetrahydrocannabinol Revisited: Synthetic Approaches Utilizing Molybdenum Catalysts
Authors: Malkov Andrei V. , Kočovský Pavel
Published: July 2002

∆9-Tetrahydrocannabinol 1 and its isomers were synthesized via domino-type methodology. The first approach, leading to (±)-1, relies on the Mo(IV)-catalyzed, one-pot cascade reaction of citral (4) with olivetol (15), affording (±)-∆9-tetrahydrocannabinol as a 69 : 31 mixture of the trans- (natural) and cis-isomers in 20% yield. The alternative approach, leading to natural (-)-1, commenced with epoxidation of (+)-limonene (R)-(+)-16; opening of the resulting cis-epoxide 17 with PhSeNa, followed by elimination, afforded tertiary alcohol 21, whose acetate 22 was treated with olivetol 15 in the presence of Mo(II) catalyst IV to afford (-)-1 in 52% yield.
Is glucose/amino acid supplementation after exercise an aid to strength training?
Authors: Williams A G , van den Oord M , Sharma A , Jones D A
Published: July 2002

Background—The precise timing of carbohydrate and amino acid ingestion relative to a bout of resistance exercise may modulate the training effect of the resistance exercise.

Objective—To assess whether regular glucose/amino acid supplementation immediately after resistance exercise could enhance the gain in muscle strength brought about by resistance training.

Methods—Seven untrained participants with a median age of 23 years and mean (SD) body mass 68.9 (13.5) kg resistance trained on a leg extension machine for five days a week for 10 weeks, using four sets of 10 repetitions. Alternate legs were trained on successive days, one leg each day. Subjects ingested either a supplement including 0.8 g glucose/kg and 0.2 g amino acids/kg, or placebo, on alternate training days immediately after training. Therefore the supplement was always ingested after training the same leg (supplement leg). Isometric, isokinetic, and 1 repetition maximum (RM) strength were measured before, during, and after training. Blood samples were analysed to determine the acute responses of insulin and glucose to resistance exercise and supplementation or placebo.

Results—Serum insulin concentration peaked 20 minutes after supplement ingestion at ninefold the placebo level, and remained significantly elevated for at least 80 minutes (p<0.01). Isometric, isokinetic, and 1 RM strength improved on both supplement and placebo legs (p<0.05). There were no significant differences in the gain in strength between the supplement leg and the placebo leg (p>0.05).

Conclusion—Regular glucose/amino acid supplementation immediately after resistance exercise is unlikely to enhance the gain in muscle strength brought about by resistance training.
Decision analysis in the surgical treatment of patients with familial adenomatous polyposis: a Dutch-Scandinavian collaborative study including 659 patients
Authors: Vasen H F A , van Duijvendijk P , Buskens E , Bülow C , Björk J , Järvinen H J , Bülow S
Published: July 2002

BACKGROUND AND AIMS

The choice of colorectal surgery in patients with familial adenomatous polyposis lies between the morbidity of proctocolectomy and ileum-pouch-anal anastomosis (IPAA) and the mortality from rectal cancer after total colectomy and ileorectal anastomosis (IRA). The aims of the present study were: (1) to assess the risk of dying from rectal cancer after IRA, (2) to compare the life expectancy between patients with an IRA and those with an IPAA, and (3) to investigate whether regular endoscopic examination of the rectum leads to detection of cancer at an earlier stage.

METHODS

Clinical and pathological data on 659 patients who underwent colectomy and ileorectal anastomosis were collected from four national polyposis registries—that is, in Denmark, Finland, Sweden, and the Netherlands. Data were analysed using survival analysis methods. Decision analysis was used to compare the life expectancy between patients with an IRA and those with an IPAA.

RESULTS

A total of 47 patients developed rectal cancer after IRA. The risk of dying from rectal cancer was 12.5% (95% confidence interval 7.1–17.9%) by age 65. Compared with IRA, IPAA would lead to an increase in life expectancy of 1.8 years. Seventy five per cent of patients with rectal cancer had a negative rectoscopy within 12 months before the diagnosis.

CONCLUSION

IRA is associated with substantial mortality due to rectal cancer. Follow up examinations of the rectum does not have sufficient preventive effect on morbidity and mortality of rectal cancer.
‘If you pay, we'll operate immediately’
Authors: Miller William L , Grødeland Åse B , Koshechkina Tatyana Y
Published: July 2002

Objectives—To study the attitudes of health care staff in four postcommunist countries towards taking gifts from their clients—and their confessed experience of actually taking such gifts.

Design—Survey questionnaire administered to officials including health care staff, supplemented by focus-group discussions with the general public.

Setting – Ukraine, Bulgaria, Slovakia and the Czech Republic.

Participants—A quota sample of 1,307 officials including 292 health care staff, supplemented by stratified national random samples of 4,778 ordinary members of the public and in-depth interviews or focus-group discussions involving another 323.

Main measurements—Explicit justifications and willingness to accept offers, reported frequency of offers, and personal confessions to accepting “money and expensive presents” as well as smaller gifts.

Results—Health care staff were far more inclined than the average official or public servant to accept “money or an expensive present” if offered, far more inclined to justify asking clients for “extra payments”, and far more inclined to confess that they had actually taken gifts from clients recently. Judged by their own confessions, hospital doctors were only rivalled by traffic police and customs officials for taking money or expensive gifts from their clients.

Conclusions—Poor pay does not explain why doctors so often took large gifts from their clients. Moral self justification, opportunity, and bargaining power are much more effective explanations.
DERANDOMIZED LEARNING OF BOOLEAN FUNCTIONS OVER FINITE ABELIAN GROUPS
Authors: SITHARAM M. , STRANEY TIMOTHY
Published: July 2002

We employ the Always Approximately Correct or AAC model defined in [35], to prove learnability results for classes of Boolean functions over arbitrary finite Abelian groups. This model is an extension of Angluin's Query model of exact learning. The Boolean functions we consider belong to approximation classes, i.e. functions that are approximable (in various norms) by few Fourier basis functions, or irreducible characters of the domain Abelian group. We contrast our learnability results to previous results for similar classes in the PAC model of learning with and without membership queries.

In addition, we discuss new, natural issues and questions that arise when the AAC model is used. One such question is whether a uniform training set is available for learning any function in a given approximation class. No analogous question seems to have been studied in the context of Angluin's Query model. Another question is whether the training set can be found quickly if the approximation class of the function is completely unknown to the learner, or only partial information about the approximation class is given to the learner (in addition to the answers to membership queries).

In order to prove the learnability results in this paper we require new techniques for efficiently sampling Boolean functions using the character theory of finite Abelian groups, as well as the development of algebraic algorithms. The techniques result in other natural applications closely related to learning, for example, query complexity of deterministic algorithms for testing linearity, efficient pseudorandom generators, and estimating VC dimensions for classes of Boolean functions over finite Abelian groups.
INDUCED REPRESENTATIONS, GAUGE FIELDS, AND QUANTIZATION ON HOMOGENEOUS SPACES
Authors: LANDSMAN N.P.
Published: July 2002

We study representations of the enveloping algebra of a Lie group G which are induced by a representation of a Lie subgroup H, assuming that G/H is reductive. Such representations describe the superselection sectors of a quantum particle moving on G/H. It is found that the representatives of both the generators and the quadratic Casimir operators of G have a natural geometric realization in terms of the canonical connection on the principal H-bundle G. The explicit expression for the generators can be understood from the point of view of conservation laws and moment maps in classical field theory and classical particle mechanics on G/H. The emergence of classical geometric structures in the quantum-mechanical situation is explained by a detailed study of the domain and possible self-adjointness properties of the relevant operators. A new and practical criterion for essential self-adjointness in general unitary representations is given.
MONEY, INFLATION AND CAPITAL ACCUMULATION
Authors: TAN KIM HENG
Published: July 2002

This paper shows that increasing the rate of monetary growth increases the capital-labor ratio in the long run when the initial inflation rate is low but decreases the capital-labor ratio when the inflation rate is high. This paper provides a theoretical justification for the empirical result by Bullard and Keating (1996) that inflation has positive real effects for low-inflation countries in the long run but negative effects for higher-inflation countries.
COMMENT ON FERMION PROPAGATOR IN REAL-TIME QUANTUM-FIELD THEORY AT FINITE TEMPERATURE AND DENSITY
Authors: NIÉGAWA A.
Published: July 2002

Two forms are available for the fermion propagator at finite temperature and density. It is shown that, when one deals with a diquark-condensation-operator inserted Green function in hot and dense QCD, the standard form of the quark propagator does not work. On the other hand, another form of the quark propagator does work.
THERMODYNAMIC PROPERTIES OF A QUANTUM GROUP BOSON GAS GLp,q(2)
Authors: JELLAL AHMED
Published: July 2002

An approach is proposed enabling to effectively describe the behavior of a bosonic system. The approach uses the quantum group GL p,q(2) formalism. Indeed, considering a bosonic Hamiltonian in terms of the GL p,q(2) generators, it is shown that its thermodynamic properties are connected to deformation parameters p and q. For instance, the average number of particles and the pressure have been computed. If p is fixed to be the same value for q, our approach coincides perfectly with some results developed recently in this subject. The ordinary results, of the present system, can be found when we take the limit p = q = 1.
DESCRIPTION OF THE BTEV DETECTOR
Authors: WANG JIANCHUN
Published: July 2002

BTeV is an experiment being constructed at the Fermilab [Formula: see text] collider, designed to study mixing, CP violation, and rare decays of beauty and charm hadrons. The detector covers the forward region (10-300 mrad), components include silicon pixels, tracking, RICH, PdWO4 electromagnetic calorimeter, and muon system. Brief description of individual detector elements are presented.
CASIMIR ENERGY OF CONFINED FIELDS: A ROLE OF THE RG-INVARIANCE
Authors: CHEREDNIKOV IGOR O.
Published: July 2002

A role of the renormalization group invariance in calculations of the ground state energy for models with confined fermion fields is discussed. The case of the (1+1)D MIT bag model with the massive fermions is studied in detail.
NONLOCAL ELECTRO-OPTIC EFFECT IN SEMICONDUCTOR THIN FILMS
Authors: SAKAI MASAMICHI
Published: July 2002

Electroreflectance (ER) spectra of GaAs thin film/ Al 0.3 Ga 0.7 As -substrate systems are investigated theoretically by taking into account the nonlocal effect caused by the presence of a crystal surface. Calculations are carried out by following the previous work by DelSole but considering influence of film thickness and nonflat-band modulation of a static electric field. It is shown from thickness variation of ER spectra that the refractive indexes of the thin films are reduced by a factor of about 0.1 when the nonlocal effect is considered.
PROPAGATION PROPERTIES OF HIGH-DENSITY EXCITON POLARITONS
Authors: Inagaki T. J. , Aihara M.
Published: July 2002

We investigate the time evolution of the exciton wave packet by an interacting exciton polariton model. The analysis is based on the equation-of-motion for the expectation value of exciton polariton operator with respect to the macroscopic quantum state. We find that the nonlinear interaction between exciton polariton leads to the extraordinary fast propagation of high-density exciton polaritons. This result helps the proper understanding of the experiments on the unusually fast propagation of exciton polaritons in strongly excited BiI 3.
SOLUTION CERTAINTY IN THECu(110)-(2 × 1)-2O2-SURFACE CRYSTALLOGRAPHY
Authors: SUN CHANG Q. , LI S. , TAY B. K. , SUN X. W. , LAU S. P.
Published: July 2002

It has been elegantly accepted that oxygen adsorption onto the Cu (110) surface induces an expansion of the first layer-spacing and a contraction of the second in addition to the alternative Cu [001] row that is either missing or forming the O-Cu-O row of high protrusions. However, it needs yet to clarify the vertical position of the oxygen and the hard-sphere models of added-, missing- and buckled-row. Here we justify that all the structures determined and all the models developed so far are correct in the sense of numerical solutions and phenomenological descriptions. A tetrahedral bond configuration of sp-orbital hybridization developed recently, however, may serve as a criterion to identify the physical solution that could account consistently for the observations using scanning tunneling microscopy/spectroscopy (STM/S), X-ray diffraction (XRD), and ultraviolet photoelectron spectroscopy (UPS).
SELF-AVOIDING WALKS ON THE 4–8 LATTICE
Authors: LIN KEH YING , CHANG CHI CHEN
Published: July 2002

We have calculated exactly the number, the mean-square end-to-end distance, the mean-square radius of gyration, and the mean-square distance of a monomer from the origin for self-avoiding walks on the 4–8 lattice up to 42 steps by computer. We estimated the connective constant and the critical amplitudes. Our numerical results are consistent with the theoretical prediction by Cardy and Saleur on the universality for certain amplitude ratios.
POLARISED TEMPERATURE DEPENDENT XANES STUDY OF SUPERCONDUCTING La2-xSrxCuO4-y UNDER- AND OVER-DOPED SINGLE CRYSTALS
Authors: CONCHA C. , GARCIA J. , BLASCO J. , GARG K. B. , SINGHAL R. K. , CHATURVEDI D.
Published: July 2002

High resolution XANES measurements have been made at the CuK-absorption edge on two La 2-x Sr x CuO 4-y single crystals; one under-doped (x = 0.13) and the other over-doped (x = 0.19). These measurements have been made in E//ab and E//c directions at several temperatures to compare the doping, orientation and temperature dependence in their behaviour. Broadly speaking, their XANES spectra resemble the typical one from a crystal with square-planar geometry and the various fine structure features assigned to the possible transitions they arise due to, particularly in terms of the fact that the 4p band in Cu splits into 4p(π) and 4p(σ) components in these square-planar systems. However, the temperature dependence of the various features in the spectra from the two crystals appear to be opposite in nature and exhibit some characteristic temperatures at which the trend seems to reverse. All the experimental results and their implication are discussed and a possibility of phase transition of these systems at lower temperatures is hinted at.
THE CHERN–SIMONS INVARIANT IN THE BERRY PHASE OF A TWO BY TWO HAMILTONIAN
Authors: LEE DUNG-HAI
Published: July 2002

By varying (x,y,z) within a manifold ℳ, the positive (negative)-energy eigenvectors of the 2 × 2 Hamiltonian H = xσx + yσy + zσz (where σx,y,z are the Pauli matrices) form a U(1) fiber bundle. For certain ℳ the bundle has non-trivial topology. For example when ℳ = S2 the associated bundle has non-zero Chern number indicating that it is topologically non-trivial at the highest level. In this paper we construct a simple 2 × 2 Hamiltonian whose eigen-vector bundle exhibits a more subtle topological non-triviality when ℳ is a closed three-manifold. This non-trivial topology is characterized by non-zero Chern-Simons invariant.
Evidence for Oxygen and Mercury Non-Stoichiometry in Hg-1201 HTC Superconductor
Authors: Costa G. A. , Carnasciali M. M. , Kaiser E.
Published: July 2002

A review of the structural existing data on Hg-1201 shows evidence of non stoichiometry of the sample.

In this compound not only oxygen but also Hg seems to be released or, perhaps, substituted.

So, the production of bulk samples with optimal oxygen doping and homogeneus Hg content could be profitable for the study of the effect of the Hg solubility, allowing to confirm its existence till to room temperatures, and to test the effect of Hg impoverishment on other critical superconducting parameter different from Tc.
SYMMETRY, INTEGRABILITY AND DEFORMATIONS OF LONG-RANGE INTERACTING HAMILTONIANS
Authors: BALLESTEROS ANGEL
Published: July 2002

The notion of coalgebra symmetry in Hamiltonian systems is analysed. It is shown how the complete integrability of some long-range interacting Hamiltonians can be extracted from their associated coalgebra structure with no use of a quantum R-matrix. Within this framework, integrable deformations can be considered as direct consequences of the introduction of coalgebra deformations (quantum algebras). As an example, the Gaudin magnet is derived from a sl(2) coalgebra, and a completely integrable deformation of this Hamiltonian is obtained through a twisted gl(2) quantum algebra.
TRANSPORT AND MAGNETIC PROPERTIES OF Bi BASED MULTIPHASE SUPERCONDUCTORS
Authors: Vašek P. , Janeček I.
Published: July 2002

A series of (Bi,Pb)SrCuCaO samples with varying volume fraction of the 2223 phase (determined by X-ray diffraction) has been prepared. Temperature dependence of the resistance, Hall effect and magnetic susceptibility has been measured. Neither susceptibility (both dc and ac) nor electrical resistivity in magnetic field reveal the presence of the low temperature (2212) phase. On the other hand the Hall voltage in the mixed state is very sensitive to the presence of different phases. Obtained results have been discussed within the frame of the effective medium approach and related to the growth mechanism of the 2223 phase.
HOW CAN AN ATOM OR ION REMEMBER ITS INITIAL STATE?
Authors: Wang J. T. , Tang F. , Bagayoko D. , Chen T.-P.
Published: July 2002

The experiment has found that in order to form the thin film of certain compound by deposition, the same compound should be used for the target material. A stoichiometric mixture of components for forming the compound by solid reaction as the target material won't do the work. It seems that the particle emitted from the target remembers its initial state, the state when it is in the compound. By perturbation approximation, we estimated the life time of the initial state of the emitted particle, if the states of the particle are represented only by the states of outer shell electrons. To elucidate the experimental finding, other factors regarding the states of the emitted particle may have to take into consideration.
NEGATIVE BINOMIAL STATES OF THE RADIATION FIELD AND THEIR EXCITATIONS ARE NONLINEAR COHERENT STATES
Authors: WANG XIAO-GUANG , FU HONG-CHEN
Published: July 2002

We show that the well-known negative binomial states of the radiation field and their excitations are nonlinear coherent states. Excited nonlinear coherent states are still nonlinear coherent states with different nonlinear functions. We finally give an exponential form of the nonlinear coherent states and remark that the binomial states are not nonlinear coherent states.
A PHENOMENOLOGICAL STUDY OF THE Si–H INFRARED SPECTRA IN POROUS AND AMORPHOUS SILICON
Authors: KAPOOR MANISH , SINGH VIJAY A.
Published: July 2002

It is observed that Si–H stretching mode vibrational spectra in porous silicon and in hydrogenated amorphous silicon: (i) is broad with a full width at half maxima of ≈20-40 cm -1; (ii) has a long low energy tail; and (iii) has a peak value shifted by 100 cm -1 from 2000 cm -1 (crystalline silicon case) to 2100 cm -1. We propose a simple phenomenological model to account for the above features. The model invokes a narrow distribution in the Si–H bond distances. The first feature namely the broadening can be satisfactorily explained. Although our model yields a low energy tail, it is not as pronounced as the experimental tail. Our model can be shown to be consistent with the third feature, namely the peak shift.
HANDWRITTEN ADDRESS INTERPRETATION: A TASK OF MANY PATTERN RECOGNITION PROBLEMS
Authors: SRIHARI SARGUR N.
Published: July 2002

A gradation of pattern discrimination problems is encountered in interpreting handwritten postal addresses. There are several multiclass discrimination problems, including handwritten numeral recognition with 10 classes, alphanumeral recognition with 36 classes, and touching-digit pair recognition with 100 classes. Word recognition with a lexicon is a problem where the number of classes varies from a few to about a thousand. Some of the discrimination techniques, particularly those with few classes, lend themselves well to neural network classification, while others are better handled by Bayesian polynomial and nearest-neighbor methods. This paper describes each of the discrimination problems and the performances of each of the subsystems in a handwritten address interpretation system developed at CEDAR.
A METHOD TO CALCULATE BIFURCATIONS IN SYNAPTICALLY COUPLED HODGKIN–HUXLEY EQUATIONS
Authors: YOSHINAGA TETSUYA , SANO YASUHIKO , KAWAKAMI HIROSHI
Published: July 2002

We propose a numerical method for calculating bifurcations of periodic solutions observed in a model equation of Hodgkin–Huxley neurons coupled by excitatory synapses with a time delay. To illustrate the validity of the method, bifurcations in two-coupled Hodgkin–Huxley equations with variation of a coupling coefficient and time delay are studied.
CONSTRUCTION OF SELF-DISTRIBUTIVE OPERATIONS AND CHARGED BRAIDS
Authors: DEHORNOY PATRICK
Published: July 2002

Starting from a certain monoid that describes the geometry of the left self-distributivity identity, we construct an explicit realization of the free left self-distributive system on any number of generators. This realization lives in the charged braid group, an extension of Artin's braid group B∞ with a simple geometrical interpretation.
COMBING NILPOTENT AND POLYCYCLIC GROUPS
Authors: GILMAN ROBERT H. , HOLT DEREK F. , REES SARAH
Published: July 2002

The notable exclusions from the family of automatic groups are those nilpotent groups which are not virtually abelian, and the fundamental groups of compact 3-manifolds based on the Nil or Sol geometries. Of these, the 3-manifold groups have been shown by Bridson and Gilman to lie in a family of groups defined by conditions slightly more general than those of the automatic groups, i.e. to have combings which lie in the formal language class of indexed languages. In fact, the combings constructed by Bridson and Gilman for these groups can also be seen to be real-time languages (i.e. recognized by real-time Turing machines).

This article investigates the situation for nilpotent and polycyclic groups. It is shown that a finitely generated class 2 nilpotent group with cyclic commutator subgroup is real-time combable, as are all 2 or 3-generated class 2 nilpotent groups, and groups in specific families of nilpotent groups (the finitely generated Heisenberg groups, groups of unipotent matrices over Z and the free class 2 nilpotent groups). Further, it is shown that any polycyclic-by-finite group embeds in a real-time combable group. All the combings constructed in the article are boundedly asynchronous, and those for nilpotent-by-finite groups have polynomially bounded length functions, of a degree equal to the nilpotency class, c; this verifies a polynomial upper bound on the Dehn functions of those groups of degree c+1.