bluuebunny/crossref_metadata_2025 huggingface dataset:
A Single Amino Acid in the Reverse Transcriptase Domain of Hepatitis B Virus Affects Virus Replication Efficiency
Authors: Lin Xu , Yuan Zheng-Hong , Wu Li , Ding Jian-Ping , Wen Yu-Mei
Published: July 2002

To explore functional domains in the hepatitis B virus (HBV) polymerase, two naturally occurring HBV isolates (56 and 2-18) with 98.7% nucleic acid sequence homology but different replication efficiencies were studied. After transfection into HepG2 cells, HBV DNA isolated from intracellular virus core particles was much higher in 56-transfected cells than in cells transfected with 2-18. The structural basis for the difference in replication efficiency between these two isolates was studied by functional domain gene substitution. The complete polymerase (P) gene and its gene segments coding for the terminal protein (TP), spacer (SP), reverse transcriptase (RT), and RNase H in 2-18 were separately replaced with their counterparts from 56 to construct full-length chimeric genomes. Cell transfection analysis revealed that substitution of the complete P gene of 2-18 with the P gene from 56 slightly enhanced viral replication. The only chimeric genome that regained the high replication efficiency of the original 56 isolate was the one with substitution of the RT gene of 2-18 with that from 56. Within the RT region, amino acid differences between isolates 2-18 and 56 were located at positions 617 (methionine versus leucine), 652 (serine versus proline), and 682 (valine versus leucine). Point mutation identified amino acid 652 as being responsible for the difference in replication efficiency. Homologous modeling studies of the HBV RT domain suggest that the mutation of residue 652 from proline to serine might affect the conformation of HBV RT which interacts with the template-primer, leading to impaired polymerase activity.
Characterization of the CD154-Positive and CD40-Positive Cellular Subsets Required for Pathogenesis in Retrovirus-Induced Murine Immunodeficiency
Authors: Green Kathy A. , Noelle Randolph J. , Durell Brigit G. , Green William R.
Published: July 2002

Genetically susceptible C57BL/6 (B6) mice that are infected with the LP-BM5 isolate of murine retroviruses develop profound splenomegaly, lymphadenopathy, hypergammaglobulinemia, terminal B-cell lymphomas, and an immunodeficiency state bearing many similarities to the pathologies seen in AIDS. Because of these similarities, this syndrome has been called murine AIDS (MAIDS). We have previously shown that CD154 (CD40 ligand)-CD40 molecular interactions are required both for the initiation and progression of MAIDS. Thus, in vivo anti-CD154 monoclonal antibody (MAb) treatment inhibited MAIDS symptoms in LP-BM5-infected wild-type mice when either a short course of anti-CD154 MAb treatment was started on the day of infection or a course was initiated 3 to 4 weeks after LP-BM5 administration, after disease was established. Here, we further characterize this required CD154-CD40 interaction by a series of adoptive transfer experiments designed to elucidate which cellular subsets must express CD154 or CD40 for LP-BM5 to induce MAIDS. Specifically with regard to CD154 expression, MAIDS-insusceptible B6 nude mice reconstituted with highly purified CD4+T cells from wild-type, but not from CD154 knockout, B6 donors displayed clear MAIDS after LP-BM5 infection. In contrast, nude B6 recipients that received CD8+T cells from wild-type B6 donors did not develop MAIDS after LP-BM5 infection. B6 CD40 knockout mice, which are also relatively resistant to LP-BM5-induced MAIDS, became susceptible to LP-BM5-induced disease after reconstitution with highly purified wild-type B cells but not after receiving purified wild-type dendritic cells (DC) or a combined CD40+population composed of DC and macrophages obtained from B6 SCID mouse donors. Based on these and other experiments, we thus conclude that the cellular basis for the requirement for CD154-CD40 interactions for MAIDS induction and progression can be accounted for by CD154 expression on CD4+T cells and CD40 expression on B cells.
Rev-Independent Simian Immunodeficiency Virus Strains Are Nonpathogenic in Neonatal Macaques
Authors: von Gegerfelt Agneta S. , Liska Vladimir , Li Pei-Lin , McClure Harold M. , Horie Kyoji , Nappi Filomena , Montefiori David C. , Pavlakis George N. , Marthas Marta L. , Ruprecht Ruth M. , Felber Barbara K.
Published: July 2002

The viral protein Rev is essential for the export of the subset of unspliced and partially spliced lentiviral mRNAs and the production of structural proteins. Rev and its RNA binding site RRE can be replaced in both human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) by the constitutive RNA transport element CTE of the simian type D retroviruses. We used neonatal macaques as a sensitive animal model to evaluate the pathogenicity of a pair of SIV mutant strains generated from Rev-independent molecular clones of SIVmac239 which differ only in the presence of thenefopen reading frame. After high primary viremia, all animals remained persistently infected at levels below the threshold of detection. All macaques infected as neonates developed normally, and none showed any signs of immune dysfunction or disease during follow-up ranging from 2.3 to 4 years. Therefore, the Rev-RRE regulatory mechanism plays a key role in the maintenance of high levels of virus propagation, which is independent of the presence ofnef. These data demonstrate that Rev regulation plays an important role in the pathogenicity of SIV. Replacement of Rev-RRE by the CTE provides a novel approach to dramatically lower the virulence of a pathogenic lentivirus. These data further suggest that antiretroviral strategies leading to even a partial block of Rev function may modulate disease progression in HIV-infected individuals.
The Liver Is a Major Organ for Clearing Simian Immunodeficiency Virus in Rhesus Monkeys
Authors: Zhang Linqi , Dailey Peter J. , Gettie Agegnehu , Blanchard Jim , Ho David D.
Published: July 2002

Infection with human or simian immunodeficiency virus (SIV) is characterized by the rapid turnover of both viral particles and productively infected cells. It has recently been reported that the clearance of SIV in vivo is exceedingly fast, with half-lives on the order of minutes. The underlying mechanism or site responsible for this rapid clearance, however, remains unknown. To investigate this issue, we chose to infuse infectious SIVmac239 grown from autologous peripheral blood mononuclear cells that were radioactively labeled by [35S]methionine and [35S]cysteine. This approach eliminates from the viral membrane alloantigens that may have a significant impact on viral clearance. In addition, this approach also permits identification of the sites of viral clearance by measuring the radioactive intensity, even if degradation of SIV RNA occurs in tissues. We now report that the half-life of infused SIV in blood is extremely close to estimates from a previous study, in which unlabeled SIV grown in a heterologous cell line was used. The allogeneic effect due to the presence of human antigens on the surfaces of virions may, therefore, play a minimal role in the high rate of virion clearance. Moreover, close to 30% of infused radioactivity was found in the liver and measureable amounts were detected in the lungs (5.4%), lymph nodes (3.0%), and spleen (0.4%). The detection of a significant proportion of infused virus in the liver suggests that viral clearance from circulation is mediated by a common, nonspecific mechanism, such as the phagocytic functions of the reticuloendothelial system. The rapid clearance and degradation of exogenously infused virions may pose a major obstacle for gene therapy with viral vectors, unless strategies to overcome the rapid in vivo elimination of these particles are developed.
Evolution of Bacteriophage in Continuous Culture: a Model System To Test Antiviral Gene Therapies for the Emergence of Phage Escape Mutants
Authors: Lindemann Björn F. , Klug Christian , Schwienhorst Andreas
Published: July 2002

The emergence of viral escape mutants is usually a highly undesirable phenomenon. This phenomenon is frequently observed in antiviral drug applications for the treatment of viral infections and can undermine long-term therapeutic success. Here, we propose a strategy for evaluating a given antiviral approach in terms of its potential to provoke the appearance of resistant virus mutants. By use of Qβ RNA phage as a model system, the effect of an antiviral gene therapy, i.e., a virus-specific repressor protein expressed by a recombinantEscherichia colihost, was studied over the course of more than 100 generations. In 13 experiments carried out in parallel, 12 phage populations became resistant and 1 became extinct. Sequence analysis revealed that only two distinct phage mutants emerged in the 12 surviving phage populations. For both escape mutants, sequence variations located in the repressor binding site of the viral genomic RNA, which decrease affinity for the repressor protein, conferred resistance to translational repression. The results clearly suggest the feasibility of the proposed strategy for the evaluation of antiviral approaches in terms of their potential to allow resistant mutants to appear. In addition, the strategy proved to be a valuable tool for observing virus-specific molecular targets under the impact of antiviral drugs.
Both R5 and X4 Human Immunodeficiency Virus Type 1 Variants Persist during Prolonged Therapy with Five Antiretroviral Drugs
Authors: van Rij Ronald P. , Visser Janny A. , van Praag Rieneke M. E. , Rientsma Ronald , Prins Jan M. , Lange Joep M. A. , Schuitemaker Hanneke
Published: July 2002

A viral reservoir of human immunodeficiency virus type 1 (HIV-1)-infected, resting CD4+T cells persists despite suppression of plasma viremia by combination antiretroviral therapy. In a longitudinal analysis of three patients treated with a five-drug regimen, both R5 and X4 HIV-1 variants persisted in the cellular reservoir for up to 3 years.
Stable Replication of Papillomavirus Genomes in
Saccharomyces cerevisiae
Authors: Angeletti Peter C. , Kim Kitai , Fernandes Fiona J. , Lambert Paul F.
Published: July 2002

Papillomaviruses normally replicate in stratified squamous epithelial tissues of their mammalian hosts, in which the viral genome is found as a nuclear plasmid. Two viral proteins, E1, a helicase, and E2, a transcriptional activator and plasmid maintenance factor, are known to contribute to the episomal replication of the viral genome. Recently, our laboratory discovered that papillomaviruses can also replicate in an E1-independent manner in mammalian cells (K. Kim and P. F. Lambert, Virology, in press; K. Kim and P. F. Lambert, submitted for publication). In this study, we describe experiments investigating the capacity of the human papillomavirus type 16 (HPV16) genome to replicate in yeast (
Saccharomyces cerevisiae
). The full-length HPV16 genome, when linked in
cis
to a selectable yeast marker gene, either
TRP1
or
URA3
, could replicate stably as an episome in yeast. The replication of papillomavirus genomes in yeast is not limited to HPV16. Bovine papillomavirus type 1 and HPV6b, -11, -16, -18, and -31 were all capable of replicating in short-term assays over a period of 20 cell doublings. The long-term persistence of viral episomes did not require any one viral gene, as mutant genomes defective in single genes also replicated episomally. These results indicate that the viral episome can replicate in the absence of the E1 DNA helicase. Similarly, E2 was also not required for replication in yeast, and E2 mutant viral genomes were stably maintained in the absence of selection, indicating the existence of an E2-independent mechanism for plasmid maintenance. The episomal replication of papillomavirus genomes in yeast provides a genetically manipulatable system in which to investigate cellular factors required for episomal replication and may provide a novel means for generating infectious papillomavirus.
Predicting and Calculating Complex Phase Equilibrium in Supercritical Fluid Systems with a New Technique
Authors: Stateva Roumiana P.
Published: July 2002

A general approach to multiphase equilibrium calculations with particular application to vapour-liquid-liquid and liquid-liquid-liquid systems is presented. The capabilities of the new technique to correctly predict and calculate complex phase equilibrium are tested on five highly non-ideal systems, relevant to supercritical fluid extraction. The thermodynamic models applied are the recently proposed MHV2 model and the Redlich-Kwong-Soave cubic equation of state.
The Amino and Deamino Analogues of 8-D-Homoarginine-Vasopressin with p-Substituted Phenylalanine in Position 2 in Activation of Factor VIII and Tissue Plasminogen Activator in Primates
Authors: Vilhardt Hans , Barth Tomislav , Žertová Miroslava , Procházka Zdenko , Velek Jiří
Published: July 2002

The replacement of L-Tyr in dDAVP by L-Tyr(Me), L- or D-Phe(pMe), L- or D-Phe(pEt) in combination with substitution of D-arginine by D-homoarginine resulted in dissociation of Factor VIII and tPA activating properties or in abilities to decrease the levels of circulating Factor VIII and tPA levels in blood of squirrel monkeys.
Infrared Study of Acetic Acid Solutions in CCl4
Authors: Malijevská Ivona , Polášek Martin
Published: July 2002

Spectra of acetic acid solutions in carbon tetrachloride were taken at room temperature over the concentration range 0.025-0.00125 mol dm-3. Solutions of acetic acid were modelled as an ideal mixture of monomers, and cyclic and linear dimers. Regression analysis effected separation of the experimental envelope into its component bands. Band shapes were approximated by a Lorenzian function with the resolved band peak frequencies 1 712 cm-1 for the cyclic dimer, 1 724 cm-1 for the linear dimer and 1 765 cm-1 for the acetic acid monomer. Mean values of equilibrium constants for the standard state of unit concentration are 2 700 for the cyclic and 393 for the linear dimer, respectively.
Hydrolytic Reactions of Methylfluorophosphonates with Cyclodextrins
Authors: Cabal Jiří
Published: July 2002

Reactions of three methylfluorophosphonates (isopropyl, 1,2,2-trimethylpropyl, and cyclohexyl) with α-, β- and γ-cyclodextrins were investigated. The cyclodextrins were found to react with stereoisomers of the methylfluorophosphonates at different rates depending on the location of the substituents at the phosphorus atom. The dependence of the rate increase on cyclodextrin concentration showed a saturation effect. The reactivity of the inclusion complexes of the cyclodextrins with the methylfluorophosphonates depended on the size of the alkyl part of the phosphonate molecule as well as on the size of the cavity of the cyclodextrins. Dependences of the reaction rates on temperature and pH of the reaction medium were recorded. Kinetic data have been used to evaluate the cyclodextrins as the catalysts.
A Nonequilibrium Model of Distillation Stage with Possible Occurrence of Two Liquid Phases
Authors: Eckert Egon
Published: July 2002

A model of the rectification column stage is proposed in which the possible splitting into two liquid phases may occur. For this case, the equilibrium stage concept has hitherto been employed in the literature. In this work it is shown that even in this situation, it is possible to use, under certain simplifying assumptions, the up-to-date nonequilibrium stage concept. For solving the proposed model, a global approach is suggested with retaining the problem dimension regardless of the number of coexisting liquid phases
Adsorption of Vapours of Some Organic Compounds on Surface of Iron-Substituted Layered Vanadyl Phosphate
Authors: Hradil Pavel , Votinský Jiří , Komárek Karel , Zima Vítězslav , Kalousová Jaroslava , Melánová Klára , Beneš Ludvík
Published: July 2002

Gas chromatographic measurement of specific retention volumes of vapours of selected groups of organic compounds has been used to determine differential molar enthalpy of adsorption of their molecules on the surface of layered vanadyl phosphate substituted with ferric ions having the composition of [Fe(H2O)]0.20(VO)0.80PO4. Various types of bonds of the molecules to the surface of the layered adsorbent including their probable orientation with respect to the layers have been discussed. It was observed a dependence of the specific peak elution volume and shape of chromatographic peak on the sample size in the cases of those compounds whose molecules are chemically bound to the adsorbent surface. A connection is pointed out between the adsorption strength of the organic molecules on the layered adsorbent and the tendency of the system to undergo intercalation reaction.
Synthesis and NMR Spectra of 1,6-Anhydro-2,3-dideoxy-2,3-epimino- and 1,6-Anhydro-3,4-dideoxy-3,4-epimino-β-D-hexopyranoses
Authors: Karban Jindřich , Buděšínský Miloš , Černý Miloslav , Trnka Tomáš
Published: July 2002

A complete series of 2,3-dideoxy-2,3-epimino- and 3,4-dideoxy-3,4-epimino-1,6-anhydro-β-D-hexopyranoses were prepared by lithium aluminum hydride reduction of the corresponding trans-azido tosylates or trans-azido epoxides of 1,6-anhydro-β-D-hexopyranoses. The structure of the epimino derivatives was confirmed by 1H and 13C NMR spectra.
Functional instability in non-contact ankle ligament injuries
Authors: Rose Alison , Lee Robert J , Williams Rachel M , Thomson Lindsay C , Forsyth Anne
Published: July 2002

Objectives—To measure objectively functional standing balance in the acute stages of non-contact ankle sprain, and to compare patients with controls.

Methods—A Chattanooga balance machine was used to measure postural stability in patients with acute ankle sprain and uninjured controls over a two week period, in one and two legged stance, with eyes open and closed. Participants also completed the Olerud and Molander questionnaire to provide a subjective measure of ankle function.

Results—There was a highly significant improvement in questionnaire scores for the patients during the study period (p<0.0001). Patients appeared to be less stable than controls in all balance tests, although the difference did not reach significance. There was evidence of improvement over time in the number of tests successfully completed on the injured leg in single legged stance with eyes closed (p = 0.043) between visits 1 and 3.

Conclusions—The patient group showed a subjective improvement, which supports clinical experience of treating acute ankle injuries. There is some evidence that on average the patient group appeared to be less stable than controls in all balance tests, although the difference did not reach statistical significance, even on the uninjured leg. There is a need to carry out further studies to confirm the results found in this pilot study and to investigate the hypotheses generated. It would be useful to evaluate a simple test that could be used clinically to monitor progress after ankle injury, and also to identify athletes with decreased functional stability, who may be more at risk of sustaining ankle injury.
Hormone levels of world class cyclists during the Tour of Spain stage race
Authors: Lucía A , Díaz B , Hoyos J , Fernández C , Villa G , Bandrés F , Chicharro J L
Published: July 2002

Objectives—To evaluate the hormonal response to strenuous endurance exercise performed by elite athletes.

Methods—Nine professional cyclists (mean (SD) age 28 (1) years; mean (SD) Vo2max75.3 (2.3) ml/kg/min) who participated in a three week tour race (Vuelta a España 1999) were selected as subjects. Morning urinary levels of 6-sulphatoxymelatonin (aMT6s) and morning serum levels of testosterone, follicle stimulating (FSH), luteinising hormone (LH), and cortisol were measured in each subject at t0(before the competition), t1(end of first week), t2(end of second week), and t3(end of third week). Urine samples of aMT6s were also evaluated in the evening at t0, t1, t2, and t3.

Results—Mean urinary aMT6s levels had increased significantly (p<0.01) during the day after each stage (1091 (33)v683 (68) ng/ml at t1; 955 (19)v473 (53) ng/ml at t2; 647 (61)v337 (47) ng/ml at t3). Both morning and evening aMT6s levels decreased significantly during the study. A similar pattern was observed for morning serum levels of cortisol and testosterone.

Conclusions—The results suggest that the basal activity of the pineal gland, adrenal glands, and testis may be decreased after consecutive days of intense, long term exercise.
Gastrointestinal cell proliferation and crypt fission are separate but complementary means of increasing tissue mass following infusion of epidermal growth factor in rats
Authors: Berlanga-Acosta J , Playford R J , Mandir N , Goodlad R A
Published: July 2002

BACKGROUND AND AIMS

Epidermal growth factor (EGF) is a potent mitogen for the gastrointestinal tract and also influences the number of new crypts formed by crypt fission. The time course of these events and possible linkage between these two complementary mechanisms is however poorly understood. We therefore examined the temporal relationship of proliferation and fission in rats treated with EGF.

METHODS

Osmotic minipumps were implanted subcutaneously into male Wistar rats to infuse EGF continuously (60 μg/rat/day) for periods of 1–14 days. Proliferation and crypt branching were quantified following vincristine induced metaphase arrest and morphometric assessment of microdissected tissue.

RESULTS

In the small intestine, EGF significantly increased epithelial cell proliferation and crypt and villus area after 24 hours of EGF, although maximal effects were only reached following six days of infusion. EGF also resulted in an approximate 30% reduction in crypt fission in the small bowel. In the colon, EGF caused a twofold increase in epithelial cell proliferation one day after infusion, from 15.3 (2.3) to 29.6 (3.5) metaphases per crypt (p<0.01). Maximal effects were seen in rats receiving EGF for seven days. For all time points, colonic crypt size increased in response to EGF. The amount of branching increased following one day of infusion with EGF (from 15.3 (1.9) to 32.4 (5.5)%; p<0.001) but was significantly lower (approximately 25% of control values) following longer periods of infusion. Crypt fission did not correlate with crypt area.

CONCLUSION

EGF has profound effects on cell proliferation and also altered crypt fission, with its actions on crypt fission most pronounced in the colon where it first increased and then decreased fission. EGF can thus be a potent stimulus for crypt fission during short term infusion and may reduce the number of branched crypts present in a resting or quiescent stage. Growth factors can alter cell mass by two separate but linked mechanisms, namely altered cell production and crypt fission.
Balancing rationalities: gatekeeping in health care
Authors: Willems Dick L
Published: July 2002

Physicians are increasingly confronted with the consequences of allocation policies. In several countries, physicians have been assigned a gatekeeper role for secondary health care. Many ethicists oppose this assignment for several reasons, concentrating on the harm the intrusion of societal arguments would inflict on doctor-patient relations. It is argued that these arguments rest on a distinction of spheres of values and of rationality, without taking into account the mixing of values and rationalities that takes place in everyday medical practice. If medical practice, then, does not follow a single, pure rationality, can it also incorporate the societal rationality of the gatekeeper role?

Using a case from general practice, I try to show how physicians may integrate societal arguments into their practice in a morally acceptable way. A version of the model of reflective equilibrium and especially Beauchamp and Childress's safeguards, may be helpful both to analyse and teach such balancing of values and rationalities.
In vitro toxicology of respirable Montserrat volcanic ash
Authors: Wilson Martin R , Stone Vicki , Cullen Richard T , Searl Alison , Maynard Robert L , Donaldson Kenneth
Published: July 2002

OBJECTIVES

In July 1995 the Soufriere Hills volcano on the island of Montserrat began to erupt. Preliminary reports showed that the ash contained a substantial respirable component and a large percentage of the toxic silica polymorph, cristobalite. In this study the cytotoxicity of three respirable Montserrat volcanic ash (MVA) samples was investigated: M1 from a single explosive event, M2 accumulated ash predominantly derived from pyroclastic flows, and M3 from a single pyroclastic flow. These were compared with the relatively inert dust TiO2and the known toxic quartz dust, DQ12.

METHODS

Surface area of the particles was measured with the Brunauer, Emmet, and Teller (BET) adsorption method and cristobalite content of MVA was determined byxray diffraction (XRD). After exposure to particles, the metabolic competence of the epithelial cell line A549 was assessed to determine cytotoxic effects. The ability of the particles to induce sheep blood erythrocyte haemolysis was used to assess surface reactivity.

RESULTS

Treatment with either MVA, quartz, or titanium dioxide decreased A549 epithelial cell metabolic competence as measured by ability to reduce 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). On addition of mannitol, the cytotoxic effect was significantly less with M1, quartz, and TiO2. All MVA samples induced a dose dependent increase in haemolysis, which, although less than the haemolysis induced by quartz, was significantly greater than that induced by TiO2. Addition of mannitol and superoxide dismutase (SOD) significantly reduced the haemolytic activity only of M1, but not M2 or M3, the samples derived from predominantly pyroclastic flow events.

CONCLUSIONS

Neither the cristobalite content nor the surface area of the MVA samples correlated with observed in vitro reactivity. A role for reactive oxygen species could only be shown in the cytotoxicity of M1, which was the only sample derived from a purely explosive event. These results suggest that in general the bioreactivity of MVA samples in vitro is low compared with pure quartz, but that the bioreactivity and mechanisms of biological interaction may vary according to the ash source.
Risk of mesothelioma from exposure to crocidolite asbestos: a 1995 update of a South African mortality study
Authors: Kielkowski Danuta , Nelson Gillian , Rees David
Published: July 2002

OBJECTIVE

To find the risk of developing mesothelioma in a cohort born in 1916–36 in Prieska, Northern Cape Province, South Africa.

METHODS

A birth cohort mortality study was carried out in a small town in the Northern Cape Province, South Africa, with a history of crocidolite asbestos mining and milling. The cohort comprised all white births registered in the magisterial district of Prieska from 1916 to 1936, inclusive (2390). Causes of death due to mesothelioma and other cancers as recorded on medical certificates of cause of death were investigated. Person-years analysis was used to calculate mortalities due to mesothelioma, other respiratory cancers, and other non-respiratory cancers. Proportional cancer mortalities were also calculated for mesothelioma and other specific neoplasms.

RESULTS

The follow up rate for the cohort was 74.3% in 1995, and 683 traced members (38.6%) had died. Cause of death was unknown for 6.4% of deaths. There were 118 cases of cancer, 28 of them from mesothelioma, giving a cause specific mortality for mesothelioma of 277 (170–384) per 106person-years. The rates for men and women were 366 and 172 per 106person-years, respectively. The mortality for lung cancer (29 deaths) was 287 (135–436) per 106person-years, and that for other non-respiratory cancers (60 deaths) was 593 (442–745). Two cases of laryngeal and four of colon cancer were observed. All cancer mortality, mesothelioma, and lung cancer proportional cancer mortality ratios were increased.

CONCLUSION

The mortality for mesothelioma in men was twice that in women, probably because men were more likely to have had both occupational and environmental exposure to asbestos. Nevertheless, the mortality in women was still high and is probably indicative of the environmental exposure as white women were rarely employed in the asbestos industry in the Prieska area. Due to the long latency from first exposure to diagnosis of the neoplasm, the cause specific mortality in this cohort could be expected to increase rapidly over the next 10 years.
Cryptococcosis in AIDS
Authors: Imwidthaya P , Poungvarin N
Published: July 2002

A total of 87 patients (17 female, 70 male) were admitted to Siriraj Hospital, Mahidol University, Bangkok, Thailand, from January 1996 to December 1997, with a diagnosis of cryptococcal meningitis and underlying AIDS. The age range was 14–70 years, mean 32.1. Six females (35%) and thirty-one males (44%) died, while the others were discharged home after clinical improvement. The mean duration of admission of those who died was 14.5 days, which was shorter than that of the patients who survived (25.7 days). Cerebral cryptococcosis was diagnosed using culture (100%), India ink preparation (91%), latex agglutination test (100%), and polymerase chain reaction (86%). Polymerase chain reaction fingerprinting of Cryptococcus neoformans revealed 99% serotype A and 1% serotype B. The mean minimum inhibitory concentrations of amphotericin B, flucytosine, fluconazole and itraconazole against 87 isolates of C neoformans were 0.55 μg/ml (0.25–1, SD = 0.22), 9.5 μg/ml (2–20, SD = 4.91), 6.9 μg/ml (1–16, SD = 4.42) and 0.36 μg/ml (0.125–1.0, SD = 0.23), respectively. These findings showed that the cryptococcal infections were sensitive to these antifungal agents.
Primary biliary cirrhosis: new perspectives in diagnosis and treatment
Authors: Prince Martin I , Jones David E J
Published: July 2002

Primary biliary cirrhosis (PBC) is a chronic autoimmune disease characterised by cholestatic liver function tests, antimitochondrial antibodies, and abnormal liver histology. Early descriptions of a rare rapidly progressive disease no longer reflect the more indolent progress often seen today. Many patients have significant long term morbidity through symptoms such as fatigue and itch with a minority progressing to liver failure and need for transplantation. The current data on the diagnosis, clinical progression, and treatment of PBC are reviewed.
RAPD markers as predictors of infectious hypodermal and hematopoietic necrosis virus (IHHNV) resistance in shrimp (Litopenaeus stylirostris)
Authors: Hizer Suzanne E , Dhar Arun K , Klimpel Kurt R , Garcia Denise K
Published: July 2002

Random amplified polymorphic DNA (RAPD) fingerprints of two shrimp populations (Litopenaeus stylirostris) were compared to find genetic marker(s) that may be associated with infectious hypodermal and hematopoietic necrosis virus (IHHNV) resistance or susceptibility. Of the 100 10-mer random primers and 100 intersimple-sequence repeat (ISSR) primers screened, five provided markers specific to the Super Shrimp population and three provided markers specific to the wild caught population. The two populations were further characterized for relative viral load (reported as cycle threshold, CT) using real-time quantitative PCR with primers specific to the IHHNV genome. The β-actin gene was amplified to serve as a control for normalization of the IHHNV viral load. The mean viral load was significantly lower (CT = 34.58; equivalent to 3.3 × 101 copies of IHHNV genome/ng DNA) in Super Shrimp than in the wild caught population (CT = 23.49; equivalent to 4.2 × 104 copies/ng DNA; P < 0.001; CT values are inversely related to viral load). A preliminary prediction model was created with Classification and Regression Tree (CART) software (Salford Systems, San Diego, Calif.), where the resultant decision tree uses the presence or absence of seven RAPD markers as predictors of the relative viral load.Key words: RAPD, quantitative PCR, Litopenaeus stylirostris, shrimp, genetic markers.
Identification of mitotic chromosomes of tuberous and non-tuberousSolanumspecies (Solanum tuberosumandSolanum brevidens) by GISH in their interspecific hybrids
Authors: Gavrilenko T , Larkka J , Pehu E , Rokka V -M
Published: July 2002

GISH (genomic in situ hybridization) was applied for the analysis of mitotic chromosome constitutions of somatic hybrids and their derivatives between dihaploid clones of cultivated potato (Solanum tuberosum L.) (2n = 2x = 24, AA genome) and the diploid, non-tuberous, wild species Solanum brevidens Phil. (2n = 2x = 24, EE genome). Of the primary somatic hybrids, both tetraploid (2n = 4x) and hexaploid (2n = 6x) plants were found with the genomic constitutions of AAEE and AAEEEE, respectively. Androgenic haploids (somatohaploids) derived from the tetraploid somatic hybrids had the genomic constitutions of AE (2n = 2x = 24) and haploids originating from the hexaploid hybrids were triploid AEE (2n = 3x = 33 and 2n = 3x = 36). As a result of subsequent somatic hybridization from a fusion between dihaploid S. tuberosum (2n = 2x = 24, genome AA) and a triploid somatohaploid (2n = 3x = 33, genome AEE), second-generation somatic hybrids were obtained. These somatic hybrids were pentaploids (2n = 5x, genome AAAEE), but had variable chromosome numbers. GISH analysis revealed that both primary and second-generation somatic hybrids had lost more chromosomes of S. brevidens than of S. tuberosum.Key words: anther culture, genome, haploid, potato, somatic hybridization.
Étude quantitative de l'érosion en aval des dissipateurs d'énergie type auge
Authors: Amri A El , Verrette J L
Published: July 2002

Scour tests on downstream roller bucket energy dissipators have shown that, at the equilibrium, bed characteristics are mainly influenced by the discharge and by the height of the bucket lip. The discharge affects scour characteristics, without however modifying the shape of the bed. On the other hand, the height of the bucket lip simultaneously affects scour characteristics and the shape of the bed mainly in the vicinity of the structure. In the latter area, for larger values of the height of the bucket lip, one observes a deposition with a small depression on the top and, on the contrary, when the height of the bucket lip is small, one observes an erosion. Both the depth of scour and the thickness of the deposit increase proportionally to the height of the bucket lip. Values of the other bed characteristics decrease slightly with the height of the bucket lip to reach a minimum, then they increase for higher values of the height of the bucket lip. Comparison of bed characteristics at the equilibrium with the literature shows that theory overestimates the depth of the scour measured in the laboratory by an average of 68% for the three values of discharge, underestimates the impact distance by about 6% for low discharges, and overestimates it by 10% for the highest discharge.Key words: hydraulic energy dissipation, roller bucket, scour mecanism, scour, small-scale model.
A feel for the template: zinc finger protein transcription factors and chromatin
Authors: Urnov Fyodor D
Published: July 2002

Transcription factors and chromatin collaborate in bringing the eukaryotic genome to life. An important, and poorly understood, aspect of this collaboration involves targeting the regulators to correct binding sites in vivo. An implicit and insufficiently tested assumption in the field has been that chromatin simply obstructs most sites and leaves only a few functionally relevant ones accessible. The major class of transcription factors in all metazoa, zinc finger proteins (ZFPs), can bind to chromatin in vitro (as clearly shown for Sp1, GATA-1 and -4, and the nuclear hormone receptors, for example). Data on the accessibility of DNA within heterochromatin to nonhistone regulators (E.A. Sekinger and D.S. Gross. 2001. Mol. Cell 105: 403414; C. Jolly et al. 2002. J. Cell. Biol. 156: 775781) and the ability of the basal transcription machinery to reside within highly condensed chromatin (most recently, R. Christova and T. Oelgeschlaeger. 2002. Nat. Cell Biol. 4: 7982) further weaken the argument that chromatin acts as an across-the-board deterrent to ZFP binding. These proteins, however, do not bind promiscuously in vivo, and recent data on human cells (C.E. Horak et al. 2002. Proc. Natl. Acad. Sci. U.S.A. 99: 29242929) confirm earlier data on budding yeast (B. Ren et al. 2000. Science (Washington, D.C.), 290: 23062309) that primary DNA sequence, i.e., density of binding sites per unit DNA length, is not the primary determinant of where a ZFP transcription factor will bind in vivo. This article reviews these data and uses ZFP transcription factors as a model system to compare in vitro binding to chromatin by transcription factors with their in vivo behavior in gene regulation. DNA binding domain structure, nonrandom nucleoprotein organization of chromatin at target promoters, and cooperativity of regulator action may all contribute to target site selection in vivo.Key words: zinc finger protein, chromatin, transcriptional control, nucleosome.
Growth and crown morphological responses of boreal conifer seedlings and saplings with contrasting shade tolerance to a gradient of light and height
Authors: Claveau Yves , Messier Christian , Comeau Philip G , Coates K Dave
Published: July 2002

The effects of gradients in light levels and tree height on growth and crown attributes of six conifer species were studied in eastern and western Canada. Three conifers were studied in British Columbia (Abies lasiocarpa (Hook.) Nutt., Picea glauca (Moench) Voss × Picea engelmannii Parry ex Engelm., and Pinus contorta Dougl. ex Loud. var. latifolia Engelm.), and three in Quebec (Abies balsamea (L.) Mill., Picea glauca, and Pinus banksiana Lamb.). For several growth and morphological parameters, conifers reacted strongly to both an increase in light and tree height. Significant or nearly significant interactions between light classes and height were found for height and diameter growth of most species as well as for many crown attributes for both Abies and Picea. These interactions usually indicated that growth or morphological changes occurred with increasing height from a certain light level. Within a single genus, both eastern and western tree species showed the same overall acclimation to light and height. As generally reported, Pinus species showed less variation in growth and morphological responses to light than Abies and Picea species.
Oxygen as a regulator of cellular phenotypes in pregnancy and cancer
Authors: Lash Gendie E , Postovit Lynne-Marie , Matthews Nicola E , Chung Eugene Y , Canning Matthew T , Pross Hugh , Adams Michael A , Graham Charles H
Published: July 2002

Cellular phenotype is determined by genetic and microenvironmental factors. There is evidence that tissue oxygenation status is one of the microenvironmental factors regulating cellular behaviour. Both normal and pathological processes such as blastocyst implantation in the uterus, placentation, and rapidly growing tumours occur under conditions characterized by relatively low oxygen levels. In this review, we address the effects of low oxygen concentrations on the phenotype of trophoblast and cancer cells. We provide evidence that oxygenation levels play an important role in the regulation of normal and pathological cellular invasiveness as it occurs during trophoblast invasion of the uterus and in tumour progression and metastasis, drug resistance in cancer, and antitumour activity of natural killer cells of the immune system.Key words: hypoxia, pregnancy, cancer.
ON GELFAND–DICKEY AND DRINFELD–SOKOLOV SYSTEMS
Authors: GESZTESY F. , RACE D. , UNTERKOFLER K. , WEIKARD R.
Published: July 2002

We study the connections between Gelfand–Dickey (GD) systems and their modified counterparts, the Drinfeld–Sokolov (DS) systems in the case of general matrix–valued coefficients with entries in a commutative algebra over an arbitrary field. Our main results describe auto–Bäcklund transformations for the GD hierarchy based on Miura–type transformations associated with factorizations of nth order linear differential expressions.
DIAGONALIZATION MODULO NORM IDEALS AND HAUSDORFF DIMENSIONALITY
Authors: XIA JINGBO
Published: July 2002

Kuroda's version of the Weyl-von Neumann theorem asserts that, given any norm ideal [Formula: see text] not contained in the trace class [Formula: see text], every self-adjoint operator A admits the decomposition A=D+K, where D is a self-adjoint diagonal operator and [Formula: see text]. We extend this theorem to the setting of multiplication operators on compact metric spaces (X, d). We show that if μ is a regular Borel measure on X which has a σ-finite one-dimensional Hausdorff measure, then the family {Mf:f∈ Lip (X)} of multiplication operators on T2(X, μ) can be simultaneously diagonalized modulo any [Formula: see text]. Because the condition [Formula: see text] in general cannot be dropped (Kato-Rosenblum theorem), this establishes a special relation between [Formula: see text] and the one-dimensional Hausdorff measure. The main result of the paper is that such a relation breaks down in Hausdorff dimensions p>1.
PSEUDO-EFFECTIVE LINE BUNDLES ON COMPACT KÄHLER MANIFOLDS
Authors: DEMAILLY JEAN-PIERRE , PETERNELL THOMAS , SCHNEIDER MICHAEL
Published: July 2002

The goal of this work is to pursue the study of pseudo-effective line bundles and vector bundles. Our first result is a generalization of the Hard Lefschetz theorem for cohomology with values in a pseudo-effective line bundle. The Lefschetz map is shown to be surjective when (and, in general, only when) the pseudo-effective line bundle is twisted by its multiplier ideal sheaf. This result has several geometric applications, e.g. to the study of compact Kähler manifolds with pseudo-effective canonical or anti-canonical line bundles. Another concern is to understand pseudo-effectivity in more algebraic terms. In this direction, we introduce the concept of an "almost" nef line bundle, and mean by this that the degree of the bundle is nonnegative on sufficiently generic curves. It can be shown that pseudo-effective line bundles are almost nef, and our hope is that the converse also holds true. This can be checked in some cases, e.g. for the canonical bundle of a projective 3-fold. From this, we derive some geometric properties of the Albanese map of compact Kähler 3-folds.
DEVELOPABLE VARIETIES OF GAUSS RANK 2
Authors: PIONTKOWSKI JENS
Published: July 2002

We classify projective varieties whose Gauss map has a two dimensional image. A global geometric description of the seven types is given.
POLYNOMIAL OBSERVABLES IN THE GRAPH PARTITIONING PROBLEM
Authors: MARCHISIO M. A.
Published: July 2002

Although NP-Complete problems are the most difficult decisional problems, it is possible to discover in them polynomial (or easy) observables. We study the Graph Partitioning Problem showing that it is possible to recognize in it two correlated polynomial observables. The particular behavior of one of them with respect to the connectivity of the graph suggests the presence of a phase transition in partitionability.
PHASE TRANSITIONS IN A MODEL FOR SOCIAL LEARNING VIA THE INTERNET
Authors: BORDOGNA CLELIA M. , ALBANO EZEQUIEL V.
Published: July 2002

Based on the concepts of educational psychology, sociology and statistical physics, a mathematical model for a new type of social learning process that takes place when individuals interact via the Internet is proposed and studied. The noise of the interaction (misunderstandings, lack of well organized participative activities, etc.) dramatically restricts the number of individuals that can be efficiently in mutual contact and drives phase transitions between "ordered states" such as the achievements of the individuals are satisfactory and "disordered states" with negligible achievements.
MONETARY COOPERATION IN EAST ASIA: A WAY FORWARD
Authors: NGIAM KEE JIN , YUEN HAZEL
Published: July 2002

This paper provides a theoretical justification for regional credit facilities such as currency swap arrangements in East Asia to ward off currency attacks and deter would be speculators. It also presents a case for monetary integration in East Asia. However, in view of the diverse economic, social and political background among the East Asian economies, a practical approach is to start off with a few small monetary unions rather than a large monetary union in the region. Lessons are drawn from a highly successful, but little known, monetary union between Brunei and Singapore.
EFFECT OF STRAIN ON THE TRANSPORT PROPERTIES OF THE MANGANITE
Authors: BASAK S. , CHAUDHURI I. , GHATAK S. K.
Published: July 2002

The effect of strain on the resistivity and thermopower of ferromagnetic manganites has been examined based on the model that incorporates the electron-lattice interaction through the Jahn–Teller effect and an effective hopping determined by nearest neighbor spin–spin correlation of t2g electrons. The metal insulator transition temperature associated with resistivity decreases with increase in strain. In the presence of large strain the system remains in the semiconducting state. Thermopower (S) is positive and increasing function of strain and it exhibits a maximum with temperature. The temperature where maximum of S appears, shifts towards higher (lower) value in the presence of magnetic field (strain). A large magneto-thermopower that depends on strain is obtained around metal–insulator transition.
MAGNETIC STRUCTURE OF ZINC-FERRITE APPROACHING NANOMETER SIZES
Authors: MORRISH A. H. , LI Z. W. , JIANG J. Z.
Published: July 2002

A unit cell of a spinel ferrite is just under 1 nm, actually about 0.8 nm. Particles approaching this size can be expected to possess properties that differ from the bulk material. Bulk polycrystalline Zn-ferrite ( ZnFe2O4 ) has been ball milled; after 50 h the average particle size is about 13 nm. The 57 Fe Mössbauer spectra at T = 4.2 K with and without a large (52 kOe) magnetic field applied longitudinally establish that the antiferromagnetic structure of the bulk has become ferrimagnetic in the ten nanometer particles via the transfer of some Zn cations from the A (tetrahedral) sites to the B (octahedral) sites. In addition, there is a large non-collinearity in the magnetic structure.
COLLECTIVE MODE IN JOSEPHSON-COUPLED LAYERED SUPERCONDUCTORS IN WEAK PARALLEL MAGNETIC FIELDS
Authors: KIM JU H.
Published: July 2002

We propose a theoretical model to account for the increase in the effect of both magnetic induction and presence of a nonequilibrium state in layered superconductors which behave as intrinsic Josephson junctions. Using this model, we investigate the phase dynamics with a magnetic field applied parallel to the superconducting layers and show that the increase in the coupling between the superconducting layers due to the increase in the effect of magnetic induction and the departure from equilibrium significantly modifies the dispersion of the Josephson plasma mode in intrinsic Josephson junctions from that in conventional stacks of Josephson junctions.
HIGH DENSITY EXCITATION EFFECTS ON EXCITONS AND ELECTRON-HOLE PAIRS IN AlxGa1-xAs/AlAs QUANTUM WIRES
Authors: BANDO K. , AKAI I. , KARASAWA T. , INOUE K. , NAKASHIMA H.
Published: July 2002

High density excitation effects on excitons in Al x Ga 1-x As/AlAs (x=0.2~0.5) quantum wires (QWRs) have been investigated. In these samples, the difference between the type-I (x≤0.3) and type-II (x≥0.4) band structures was clearly observed in high density effects on the photoluminescence (PL) and its temporal response. In the type-I samples, the PL is characterized by a fast radiative decay process reflecting intra-wire transitions. The PL peak shows a small blueshift with increasing excitation density, and the shift becomes large to 20meV under the highest excitation limit. The large shift is ascribed to intrinsic high density excitation effects appearing beyond the weak localization of the excitons ito structural fluctuations. On the other hand, in the type-II PL, a huge blueshift appears, being much larger than the localization energies of the excitons. This shift is also considered to be due to another intrinsic high-density effects brought about by the long-lived type-II excitons.