bluuebunny/crossref_metadata_2025 huggingface dataset:
ALIZARIN RED DYE AS A MARKER FOR MEASURING GROWTH INCORALLINA OFFICINALISL. (CORALLINACEAÈ, RHODOPHYTA)1
Authors: Andrake William , Johansen H. William
Published: August 2007

The vital stain alizarin red was incorporated into the calcified walls of incipient medullary cells ofCorallina officinalisL. while they were being produced in a terminal meristem. After about 5 h the stained tier of medullary cells formed a red‐purple band from which additional growth could be measured in the field and in non‐agitated cultures. Alizarin red was also taken up by epithallial cells and one month after staining, plants in the field lacked stained epithallia, whereas those in culture retained some of the stain. Possibly the lack of water motion in culture reduced the epithallial sloughing that occurs in nature. Growth rates measured by this technique were approximately 1.4 mm per month in the field and 1.2 mm per month in culture and were not affected by alizarin red.
ON THE NEED FOR REVISION OF THE TAXONOMY OF EUCHEUMA (RHODOPHYTA) IN FLORIDA AND THE CARIBBEAN SEA1,2
Authors: Cheney Donald P. , Dawes Clinton J.
Published: August 2007

Examination of the morphology and anatomy of the Florida species of Eucheuma revealed the presence of two distinct groups of plants. One group, represented by E. isiforme (C. Agardh) J. Agardh, E. nudum J. Agardh and an entity previously referred to as the “Bahia Honda form,” is characterized by terete axes, dense medullae, and stalked cystocarps containing a central fusion cell. The second group, represented by E. gelidium (J. Agardh) J. Agardh, E. acanthodadum (Harvey) J. Agardh and E. echinocarpum Areschough, is characterized by flattened axes, loose medullae, and embedded cystocarps containing a small‐celled, central sterile tissue. As the first step in circumscribing the genus Eucheuma in Florida and the Caribbean Sea, it is suggested that members of the latter group he removed from the genus due to their anomalous cystocarp construction.
PHOSPHORUS UTILIZATION AND STORAGE IN BATCH CULTURES OF THE DINOFLAGELLATE PERIDINIUM CINCTUM F. WESTII1
Authors: Elgavish Ada , Elgavish Gabriel A. , Halmann Mordechai , Berman Thomas
Published: August 2007

Peridinium cinctum f. westii (Lemm.) Lef., a dominant species in the phytoplankton of Lake Kinneret was studied in batch cultures. External orthophosphate concentrations were depleted by successive transfers to increasingly lower initial orthophosphate concentrations (P0) of 200, 50, 5, 0.6 and 0.2 μM (culture cycles of 45–64 days).

Lower cell yields were obtained as P0 decreased, but growth rates were unaffected. The decrease in an intra‐cellular P pool unextractable by cold 6% trichloroacetic acid (TCA) was shown to be responsible for the effect on cell yields. A 31P nuclear magnetic resonance (NMR) study revealed that the major constituents of this internal phosphorus pool in phosphate‐rich cells were the polyphosphates, organized in rigid aggregates of low mobility. Electron‐dense bodies which were observed in phosphate‐enriched P. cinctum cells further supported the existence of an aggregate structure of the polyphosphates. It is concluded that P. cinctum stores excess orthophosphate as polyphosphates which accumulate in a rigid morphological structure.
PHAGOTROPHIC FEEDING AND ITS IMPORTANCE TO THE LIFE CYCLE OF THE HOLOZOIC DINOFLAGELLATE,GYMNODINIUM FUNGIFORME1
Authors: Spero Howard J. , Morée Montescue D.
Published: August 2007

The holozoic dinoflagellate,Gymnodinium fungiformeAnissimova, has been observed in both asexually and sexually reproducing cultures. Asexual reproduction is characterized by zoosporangium formation and subsequent new cell release. Sexuality is gametic, and planozygotes and hypnozygotes are present. The life cycle is highly dependent on feeding, and in food‐depleted cultures the swimming cells rapidly disappear. These are replaced with resistant long‐term resting cysts. Despite its small size (8.5–19 μm),G. fungiformecan feed on prey as large as the ciliated protozoan,Condylostoma magnumSpiegel (600–1000 μm in length), or small injured metazoans, and has been cultured phagotrophically with the chlorophyte,Dunaliella salinaTeodoresco as a food source. Eleven additional species of algae including 1 chlorophyte, 7 chrysophytes and 3 rhodophytes, however, were not suitable as food sources. Feeding is characterized by the formation of ‘dynamic aggregations’ of hundreds of dinoflagellates that attach to the surface of a prey organism by a peduncle.G. fungiformeingests the cytoplasm or body fluids of its prey and a feeding aggregation can ingest aC. magnumin 20–30 minutes.
SOME ASPECTS OF MORPHOLOGICAL VARIATION IN STEPHANODISCUS NIAGARAE (BACILLARIOPHYCEAE)1
Authors: Theriot Edward , Stoermer Eugene F.
Published: August 2007

Valves of S. niagarae var. niagarae Ehr. and S. niagarae var. magnifica Fricke from geographically dispersed sediment and plankton collections were observed by light microscopy and scanning electron microscopy (LM and SEM). Measurements made by LM can be arranged so that means and ranges of diameter, areolar density, or strial density intergrade from one population into the next. Mean diameter is negatively related to increasing areolar and strial densities. No unique features observable by SEM distinguish the two described varieties. Thus, S. niagarae var. magnifica, having large diameter valves with low areolar and strial densities, may represent one end of a trend in overall variation in S. niagarae. At the opposite extreme are the populations with small valves and high areolar densities which are often erroneously referred to as S. astraea. Type material of S. niagarae lies intermediate to these forms. Three populations considered in this study have distinct morphological characteristics. Valves from Yellowstone Lake sediments have spine placements distinctly different from valves of all other populations. Specimens from Lake Superior have nearly flat central areas. Ribs of valves from Grand Traverse Bay (Lake Michigan) are covered with granules.
MUCILAGE TUBE MORPHOLOGY OF THREE TUBE‐DWELLING DIATOMS AND ITS DIAGNOSTIC VALUE1
Authors: Cox Eileen J.
Published: August 2007

Colonies of Berkeleya rutilans (Trent.) Grun., Navicula pseudocomoides Hendey and N. ramosissima (C. A. Ag.) Cleve were examined using light and electron microscopy to elucidate the structure of their mucilage tubes. Each species was found to have a characteristic tube construction which could be used for identification. A summary of features on which these species can be recognized was compiled.
MITOSIS IN THE OCTAFLAGELLATE PRASINOPHYTE,PYRAMIMONAS AMYLIFERA(CHLOROPHYTA)1
Authors: Woods Jerry K. , Triemer Richard E.
Published: August 2007

Cell division is described in the octaflagellate prasinophytePyramimonas amyliferaConrad and is compared in related genera. Basal bodies replicate at preprophase and move toward the poles. Cells remain motile throughout division. The nuclear envelope disperses and chromosomes begin to condense at prophase. Pairs of multilayered kinetochores are evident on the chromosomes of the metaphase plate. Spindle microtubules extending from the region of the basal bodies and rhizoplasts attach to the kinetochores or extend from pole to pole. Numerous vesicles and ribosomes have entered the nuclear region and the incipient cleavage furrow invaginates. The chromosomes move toward the poles at anaphase leaving a broad interzonal spindle between the two chromosomal plates. The nuclear envelope reforms first around the chromatin on the side adjacent to the spindle poles and later on the interzonal side. The cleavage furrow progresses into the interzonal spindle at telophase. By late telophase the nucleoli have reformed and the chromosomes have decondensed. The interzonal spindle has not been observed late in telophase. As the cleavage furrow nears completion the cells begin to twist and contort, ultimately separating the two cells.
Causation and Responsibility
Authors: Sartorio Carolina
Published: August 2007

In this article I examine the relation between causation and moral responsibility. I distinguish four possible views about that relation. One is the standard view: the view that an agent's moral responsibility for an outcome requires, and is grounded in, the agent's causal responsibility for it. I discuss several challenges to the standard view, which motivate the three remaining views. The final view – the view I argue for – is that causation is the vehicle of transmission of moral responsibility. According to this view, although moral responsibility does not require causation, causation still grounds moral responsibility.
Early Urban Development in the Near East
Authors: Ur Jason A. , Karsgaard Philip , Oates Joan
Published: August 2007

It has been thought that the first cities in the Near East were spatially extensive and grew outward from a core nucleated village while maintaining a more or less constant density in terms of persons or households per unit of area. The general applicability outside of the Near East of this southern Mesopotamian.derived model has been questioned recently, and variations from it are increasingly recognized. We can now demonstrate that such variation was present at the beginnings of urbanism in the Near East as well.
A MicroRNA Feedback Circuit in Midbrain Dopamine Neurons
Authors: Kim Jongpil , Inoue Keiichi , Ishii Jennifer , Vanti William B. , Voronov Sergey V. , Murchison Elizabeth , Hannon Gregory , Abeliovich Asa
Published: August 2007

MicroRNAs (miRNAs) are evolutionarily conserved, 18- to 25-nucleotide, non–protein coding transcripts that posttranscriptionally regulate gene expression during development. miRNAs also occur in postmitotic cells, such as neurons in the mammalian central nervous system, but their function is less well characterized. We investigated the role of miRNAs in mammalian midbrain dopaminergic neurons (DNs). We identified a miRNA, miR-133b, that is specifically expressed in midbrain DNs and is deficient in midbrain tissue from patients with Parkinson's disease. miR-133b regulates the maturation and function of midbrain DNs within a negative feedback circuit that includes the paired-like homeodomain transcription factor Pitx3. We propose a role for this feedback circuit in the fine-tuning of dopaminergic behaviors such as locomotion.
Replication Origin Recognition and Deformation by a Heterodimeric Archaeal Orc1 Complex
Authors: Dueber Erin L. Cunningham , Corn Jacob E. , Bell Stephen D. , Berger James M.
Published: August 2007

The faithful duplication of genetic material depends on essential DNA replication initiation factors. Cellular initiators form higher-order assemblies on replication origins, using adenosine triphosphate (ATP) to locally remodel duplex DNA and facilitate proper loading of synthetic replisomal components. To better understand initiator function, we determined the 3.4 angstrom–resolution structure of an archaeal Cdc6/Orc1 heterodimer bound to origin DNA. The structure demonstrates that, in addition to conventional DNA binding elements, initiators use their AAA+ ATPase domains to recognize origin DNA. Together these interactions establish the polarity of initiator assembly on the origin and induce substantial distortions into origin DNA strands. Biochemical and comparative analyses indicate that AAA+/DNA contacts observed in the structure are dynamic and evolutionarily conserved, suggesting that the complex forms a core component of the basal initiation machinery.
Current-Induced Hydrogen Tautomerization and Conductance Switching of Naphthalocyanine Molecules
Authors: Liljeroth Peter , Repp Jascha , Meyer Gerhard
Published: August 2007

The bistability in the position of the two hydrogen atoms in the inner cavity of single free-base naphthalocyanine molecules constitutes a two-level system that was manipulated and probed by low-temperature scanning tunneling microscopy. When adsorbed on an ultrathin insulating film, the molecules can be switched in a controlled fashion between the two states by excitation induced by the inelastic tunneling current. The tautomerization reaction can be probed by resonant tunneling through the molecule and is expressed as considerable changes in the conductivity of the molecule. We also demonstrated a coupling of the switching process so that the charge injection in one molecule induced tautomerization in an adjacent molecule.
Structure of a Tyrosine Phosphatase Adhesive Interaction Reveals a Spacer-Clamp Mechanism
Authors: Aricescu A. Radu , Siebold Christian , Choudhuri Kaushik , Chang Veronica T. , Lu Weixian , Davis Simon J. , van der Merwe P. Anton , Jones E. Yvonne
Published: August 2007

Cell-cell contacts are fundamental to multicellular organisms and are subject to exquisite levels of control. Human RPTPμ is a type IIB receptor protein tyrosine phosphatase that both forms an adhesive contact itself and is involved in regulating adhesion by dephosphorylating components of cadherin-catenin complexes. Here we describe a 3.1 angstrom crystal structure of the RPTPμ ectodomain that forms a homophilic trans (antiparallel) dimer with an extended and rigid architecture, matching the dimensions of adherens junctions. Cell surface expression of deletion constructs induces intercellular spacings that correlate with the ectodomain length. These data suggest that the RPTPμ ectodomain acts as a distance gauge and plays a key regulatory function, locking the phosphatase to its appropriate functional location.
Large Magnetic Anisotropy of a Single Atomic Spin Embedded in a Surface Molecular Network
Authors: Hirjibehedin Cyrus F. , Lin Chiung-Yuan , Otte Alexander F. , Ternes Markus , Lutz Christopher P. , Jones Barbara A. , Heinrich Andreas J.
Published: August 2007

Magnetic anisotropy allows magnets to maintain their direction of magnetization over time. Using a scanning tunneling microscope to observe spin excitations, we determined the orientation and strength of the anisotropies of individual iron and manganese atoms on a thin layer of copper nitride. The relative intensities of the inelastic tunneling processes are consistent with dipolar interactions, as seen for inelastic neutron scattering. First-principles calculations indicate that the magnetic atoms become incorporated into a polar covalent surface molecular network in the copper nitride. These structures, which provide atom-by-atom accessibility via local probes, have the potential for engineering anisotropies large enough to produce stable magnetization at low temperatures for a single atomic spin.
Microbiological Evaluation of the New VITEK 2
Neisseria
-
Haemophilus
Identification Card
Authors: Valenza Giuseppe , Ruoff Claudia , Vogel Ulrich , Frosch Matthias , Abele-Horn Marianne
Published: August 2007

VITEK 2 is an automated identification system for diverse bacterial and fungal species. A new card (the
Neisseria
-
Haemophilus
[NH] card) for the identification of
Neisseria
spp.,
Haemophilus
spp., and other fastidious gram-negative or gram-variable microorganisms has been developed, but its performance in a routine clinical laboratory has not yet been evaluated. In this study, a total of 188 bacterial strains belonging to the genera
Actinobacillus
,
Campylobacter
,
Capnocytophaga
,
Cardiobacterium
,
Eikenella
,
Gardnerella
,
Haemophilus
,
Kingella
,
Moraxella
, and
Neisseria
were investigated. The NH card was able to identify 171 strains (91%) correctly without the need for extra tests; one strain (0.5%) was misidentified, and five strains (2.7%) could not be classified. Eleven strains (5.8%) were identified with a low level of discrimination, and simple additional tests were required to increase the correct-identification rate to 96.8%. The results were available within 6 h. Based on these results, the new VITEK 2 NH card appears to be a good method for the identification of diverse groups of fastidious organisms, which would otherwise require testing with multiple systems. However, more work is needed to evaluate the performance of VITEK 2 with regard to
Haemophilus
,
Actinobacillus
,
Cardiobacterium
,
Eikenella
, and
Kingella
bacteria because of the insufficient number of strains tested in this study. Moreover, further reduction of the detection time would be desirable.
Prolonged Fecal Shedding of Hepatitis E Virus (HEV) during Sporadic Acute Hepatitis E: Evaluation of Infectivity of HEV in Fecal Specimens in a Cell Culture System
Authors: Takahashi Masaharu , Tanaka Toshinori , Azuma Masahiro , Kusano Eiji , Aikawa Tatsuya , Shibayama Takao , Yazaki Yasuyuki , Mizuo Hitoshi , Inoue Jun , Okamoto Hiroaki
Published: August 2007

To investigate the duration of fecal shedding and changing loads of hepatitis E virus (HEV) in feces and serum from patients with acute HEV infection, HEV RNA was quantitated in periodic serum and fecal specimens obtained from 11 patients with sporadic acute hepatitis E. All 11 patients had detectable HEV RNA in serum at admission, with the highest viral load being 1.9 × 10
3
to 1.7 × 10
7
copies/ml, and HEV viremia lasted until days 17 to 48 (mean, 28.3) after the onset of hepatitis. Even at the initial examination on days 10 to 29 (mean, 17.6), the HEV load in fecal supernatant was less than 5.7 × 10
4
copies/ml for 10 of the 11 patients, while for the remaining patient (patient 1) it was markedly high, 2.0 × 10
7
copies/ml on day 22. In addition, although HEV RNA in fecal supernatant continued to be positive until days 14 to 33 (mean, 22.4) for patients 2 to 11, that for patient 1 was detectable even on day 121. HEVs in fecal specimens obtained on days 22, 24, 26, 28, and 30, but not day 121, from patient 1 grew efficiently in PLC/PRF/5 cells, reaching the highest titer of up to 10
7
copies/ml in culture medium on day 50 postinoculation. The HEV genome recovered from patient 1 had 29 unique nucleotides that were not seen in any of the 25 reported HEV isolates of the same genotype over the entire genome, with six amino acid substitutions in the ORF1 protein.
Molecular Epidemiology of
Neisseria meningitidis
Isolates from an Outbreak of Meningococcal Disease among Men Who Have Sex with Men, Chicago, Illinois, 2003
Authors: Schmink Susanna , Watson John T. , Coulson Garry B. , Jones Roderick C. , Diaz Pamela S. , Mayer Leonard W. , Wilkins Patricia P. , Messonnier Nancy , Gerber Susan I. , Fischer Marc
Published: August 2007

We characterized five
Neisseria meningitidis
serogroup C isolates from a Chicago outbreak of meningococcal disease that occurred in 2003 among a community of men who have sex with men. Isolates from this outbreak were identical to each other but distinct from the clone that caused a similar outbreak in Canada in 2001.
Characterization of a G11,P[4] Strain of Human Rotavirus Isolated in South Korea
Authors: Hong Seong-Karp , Lee Sung-Geun , Lee Su-A , Kang Jin-Han , Lee Jyung-Hyun , Kim Jong-Hyun , Kim Dong-Soo , Kim Hwang-Min , Jang Young-Taek , Ma Sang-Hyuk , Kim Sun-Young , Paik Soon-Young
Published: August 2007

A novel human rotavirus strain, CUK-1, containing a G11 type combined with a P[4] type was isolated from a 1-year-old female patient with fever and severe diarrhea at Our Lady of Mercy Hospital in Incheon, South Korea. This CUK-1 strain showed the highest degree of nucleic acid similarity (98.7% and 93%) to G11 Dhaka6 and P[4] RV 5, respectively. This novel combined type of CUK-1 rotavirus strain (G11,P[4]) was uncovered from humans and is reported on here for the first time.
Mechanisms To Assess Gram Stain Interpretation Proficiency of Technologists at Satellite Laboratories
Authors: Munson Erik , Block Timothy , Basile Janice , Hryciuk Jeanne E. , Schell Ronald F.
Published: August 2007

To address Gram stain interpretation proficiency in a satellite/centralized microbiology laboratory paradigm, two programs were devised. In quality assurance program 1, nonmicrobiology technologists at satellite laboratories were required to interpret standardized Gram-stained specimens of clinical material prepared by an experienced microbiologist at a central laboratory. In quality assurance program 2, clinical Gram stains prepared and read by the satellite laboratorians were reviewed by experienced microbiologists at the central laboratory. Satisfactory performance (94%) was achieved in quality assurance program 1. In contrast, quality assurance program 2 had a significantly lower overall performance (89%;
P
< 0.0001) due to poorer identification of host cells (93%) and bacteria (84%). A variety of intervention mechanisms, including continuous monitoring, resulted in overall performance improvement (
P
≤ 0.006). While a technologist challenge has educational merit, having a microbiologist review previously read slides is a better indicator of the technologist's Gram stain interpretation proficiency.
Cardiovirus 2A Protein Associates with 40S but Not 80S Ribosome Subunits during Infection
Authors: Groppo Rachel , Palmenberg Ann C.
Published: August 2007

Host translation shutoff induced in picornavirus-infected cells is a well-known phenomenon. The mechanisms by which separate genera of the picornavirus family achieve this shutoff differ. This study examined alterations in the cellular translational components in HeLa cells infected with encephalomyocarditis virus (EMCV), a cardiovirus. In agreement with previous reports, EMCV induced a marked decrease in host mRNA translation. The inhibition correlated with the appearance of a significantly enhanced 80S peak in cells and a concomitant decrease in polysome abundance. Characterization of the 80S material revealed that these ribosomes were virtually devoid of mRNA. Viral protein 2A was tightly associated with some of the free 40S ribosome subunits, but it was not present in the 80S pool which accumulated after infection. Expression of 2A protein in cells in the absence infection was able to modulate the cellular translational environment to increase the ratio of internal ribosome entry site-dependent translation to cap-dependent translation of a reporter construct. The results provide further evidence for a role of 2A protein in the mechanism of cardiovirus-induced host translational shutoff.
Characterization of the Early Events in Dengue Virus Cell Entry by Biochemical Assays and Single-Virus Tracking
Authors: van der Schaar Hilde M. , Rust Michael J. , Waarts Barry-Lee , van der Ende-Metselaar Heidi , Kuhn Richard J. , Wilschut Jan , Zhuang Xiaowei , Smit Jolanda M.
Published: August 2007

In this study, we investigated the cell entry characteristics of dengue virus (DENV) type 2 strain S1 on mosquito, BHK-15, and BS-C-1 cells. The concentration of virus particles measured by biochemical assays was found to be substantially higher than the number of infectious particles determined by infectivity assays, leading to an infectious unit-to-particle ratio of approximately 1:2,600 to 1:72,000, depending on the specific assays used. In order to explain this high ratio, we investigated the receptor binding and membrane fusion characteristics of single DENV particles in living cells using real-time fluorescence microscopy. For this purpose, DENV was labeled with the lipophilic fluorescent probe DiD (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindodicarbocyanine, 4-chlorobenzenesulfonate salt). The surface density of the DiD dye in the viral membrane was sufficiently high to largely quench the fluorescence intensity but still allowed clear detection of single virus particles. Fusion of the viral membrane with the cell membrane was evident as fluorescence dequenching. It was observed that DENV binds very inefficiently to the cells used, explaining at least in part the high infectious unit-to-particle ratio. The particles that did bind to the cells showed different types of transport behavior leading to membrane fusion in both the periphery and perinuclear regions of the cell. Membrane fusion was observed in 1 out of 6 bound virus particles, indicating that a substantial fraction of the virus has the capacity to fuse. DiD dequenching was completely inhibited by ammonium chloride, demonstrating that fusion occurs exclusively from within acidic endosomes.
Nuclear Magnetic Resonance Structure of the N-Terminal Domain of Nonstructural Protein 3 from the Severe Acute Respiratory Syndrome Coronavirus
Authors: Serrano Pedro , Johnson Margaret A. , Almeida Marcius S. , Horst Reto , Herrmann Torsten , Joseph Jeremiah S. , Neuman Benjamin W. , Subramanian Vanitha , Saikatendu Kumar S. , Buchmeier Michael J. , Stevens Raymond C. , Kuhn Peter , Wüthrich Kurt
Published: August 2007

This paper describes the structure determination of nsp3a, the N-terminal domain of the severe acute respiratory syndrome coronavirus (SARS-CoV) nonstructural protein 3. nsp3a exhibits a ubiquitin-like globular fold of residues 1 to 112 and a flexibly extended glutamic acid-rich domain of residues 113 to 183. In addition to the four β-strands and two α-helices that are common to ubiquitin-like folds, the globular domain of nsp3a contains two short helices representing a feature that has not previously been observed in these proteins. Nuclear magnetic resonance chemical shift perturbations showed that these unique structural elements are involved in interactions with single-stranded RNA. Structural similarities with proteins involved in various cell-signaling pathways indicate possible roles of nsp3a in viral infection and persistence.
Evolution of Human Immunodeficiency Virus Type 1 Cytotoxic T-Lymphocyte Epitopes: Fitness-Balanced Escape
Authors: Liu Yi , McNevin John , Zhao Hong , Tebit Denis M. , Troyer Ryan M. , McSweyn Matthew , Ghosh Ananta K. , Shriner Daniel , Arts Eric J. , McElrath M. Juliana , Mullins James I.
Published: August 2007

CD8+cytotoxic T lymphocytes (CTL) are strong mediators of human immunodeficiency virus type 1 (HIV-1) control, yet HIV-1 frequently mutates to escape CTL recognition. In an analysis of sequences in the Los Alamos HIV-1 database, we show that emerging CTL escape mutations were more often present at lower frequencies than the amino acid(s) that they replaced. Furthermore, epitopes that underwent escape contained amino acid sites of high variability, whereas epitopes persisting at high frequencies lacked highly variable sites. We therefore infer that escape mutations are likely to be associated with weak functional constraints on the viral protein. This was supported by an extensive analysis of one subject for whom all escape mutations within defined CTL epitopes were studied and by an analysis of all reported escape mutations of defined CTL epitopes in the HIV Immunology Database. In one of these defined epitopes, escape mutations involving the substitution of amino acids with lower database frequencies occurred, and the epitope soon reverted back to the sensitive form. We further show that this escape mutation substantially diminished viral fitness in in vitro competition assays. Coincident with the reversion in vivo, we observed the fixation of a mutation 3 amino acids C terminal to the epitope, coincident with the ablation of the corresponding CTL response. The C-terminal mutation did not restore replication fitness reduced by the escape mutation in the epitope and by itself had little effect on replication fitness. Therefore, this C-terminal mutation presumably impaired the processing and presentation of the epitope. Finally, for one persistent epitope, CTL cross-reactivity to a mutant form may have suppressed the mutant to undetected levels, whereas for two other persistent epitopes, each of two mutants showed poor cross-reactivity and appeared in the subject at later time points. Thus, a viral dynamic exists between the advantage of immune escape, peptide cross-reactivity, and the disadvantage of lost replication fitness, with the balance playing an important role in determining whether a CTL epitope will persist or decline during infection.
Mouse-Adapted Ovine Scrapie Prion Strains Are Characterized by Different Conformers of PrPSc
Authors: Thackray Alana M. , Hopkins Lee , Klein Michael A. , Bujdoso Raymond
Published: August 2007

The agent responsible for prion disease may exist in different forms, commonly referred to as strains, with each carrying the specific information that determines its own distinct biological properties, such as incubation period and lesion profile. Biological strain typing of ovine scrapie isolates by serial passage in conventional mice has shown some diversity in ovine prion strains. However, this biological diversity remains poorly supported by biochemical prion strain typing. The protein-only hypothesis predicts that variation between different prion strains in the same host is manifest in different conformations adopted by PrPSc. Here we have investigated the molecular properties of PrPSc associated with two principal
Prnp

a

mouse-adapted ovine scrapie strains, namely, RML and ME7, in order to establish biochemical prion strain typing strategies that may subsequently be used to discriminate field cases of mouse-passaged ovine scrapie isolates. We used a conformation-dependent immunoassay and a conformational stability assay, together with Western blot analysis, to demonstrate that RML and ME7 PrPSc proteins show distinct biochemical and physicochemical properties. Although RML and ME7 PrPSc proteins showed similar resistance to proteolytic digestion, they differed in their glycoform profiles and levels of proteinase K (PK)-sensitive and PK-resistant isoforms. In addition, the PK-resistant core (PrP27-30) of ME7 was conformationally more stable following exposure to guanidine hydrochloride or Sarkosyl than was RML PrP27-30. Our data show that mouse-adapted ovine scrapie strains can be discriminated by their distinct conformers of PrPSc, which provides a basis to investigate their diversity at the molecular level.
Induction of CD8
+
Cells Able To Suppress CCR5-Tropic Simian Immunodeficiency Virus SIVmac239 Replication by Controlled Infection of CXCR4-Tropic Simian-Human Immunodeficiency Virus in Vaccinated Rhesus Macaques
Authors: Tsukamoto Tetsuo , Yuasa Mitsuhiro , Yamamoto Hiroyuki , Kawada Miki , Takeda Akiko , Igarashi Hiroko , Matano Tetsuro
Published: August 2007

Recent recombinant viral vector-based AIDS vaccine trials inducing cellular immune responses have shown control of CXCR4-tropic simian-human immunodeficiency virus (SHIV) replication but difficulty in containment of pathogenic CCR5-tropic simian immunodeficiency virus (SIV) in rhesus macaques. In contrast, controlled infection of live attenuated SIV/SHIV can confer the ability to contain SIV superchallenge in macaques. The specific immune responses responsible for this control may be induced by live virus infection but not consistently by viral vector vaccination, although those responses have not been determined. Here, we have examined in vitro anti-SIV efficacy of CD8
+
cells in rhesus macaques that showed prophylactic viral vector vaccine-based control of CXCR4-tropic SHIV89.6PD replication. Analysis of the effect of CD8
+
cells obtained at several time points from these macaques on CCR5-tropic SIVmac239 replication in vitro revealed that CD8
+
cells in the chronic phase after SHIV challenge suppressed SIV replication more efficiently than those before challenge. SIVmac239 superchallenge of two of these macaques at 3 or 4 years post-SHIV challenge was contained, and the following anti-CD8 antibody administration resulted in transient CD8
+
T-cell depletion and appearance of plasma SIVmac239 viremia in both of them. Our results indicate that CD8
+
cells acquired the ability to efficiently suppress SIV replication by controlled SHIV infection, suggesting the contribution of CD8
+
cell responses induced by controlled live virus infection to containment of HIV/SIV superinfection.
The ethical and legal implications of deactivating an implantable cardioverter-defibrillator in a patient with terminal cancer
Authors: England Ruth , England Tim , Coggon John
Published: August 2007

In this paper, the ethical and legal issues raised by the deactivation of implantable cardioverter-defibrillators (ICDs) in patients with terminal cancer is considered. It is argued that the ICD cannot be well described either as a treatment or as a non-treatment option, and thus raises complex questions regarding how rules governing deactivation should be framed. A new category called “integral devices” is proposed. Integral devices require their own special rules, reflecting their position as a “halfway house” between a form of treatment and a part of the body. The practical problems faced by doctors working in palliative medicine with regard to the deactivation of ICDs are also considered.
Detection of emerging diseases in occupational health: usefulness and limitations of the application of pharmacosurveillance methods to the database of the French national occupational disease surveillance and prevention network (RNV3P)
Authors: Bonneterre Vincent , Bicout Dominique J , Larabi Linda , Bernardet Cyril , Maitre Anne , Tubert-Bitter Pascale , de Gaudemaris Régis
Published: August 2007

Objective:

To test data mining methods used in pharmacosurveillance in order to identify potential emerging disease–nuisance associations in the national occupational disease surveillance and prevention network (RNV3P) database.

Methods:

Proportional reporting ratios (PRR) used in pharmacosurveillance were applied to detect disproportional reporting of disease–nuisance associations which are not compensated by the national social security system.

Results:

The 24 785 reports of the RNV3P were grouped into 1344 different disease–nuisance associations reported more than twice, of which 422 did not give entitlement to compensation by the social security system. Among these associations, 162 were potentially emergent and generated a signal, of which eight associations involve cancer.

Conclusion:

This work is the first stage of an exploratory investigation submitting the questions raised to experts and involving participants in the network in reflection on the hypotheses generated.
Substituent effects in the intramolecular photoredox reactions of benzophenones in aqueous solution
Authors: Basarić Nikola , Mitchell Devin , Wan Peter
Published: August 2007

A number of α-hydroxy-3-benzylbenzophenones 7–11 have been synthesized for the purpose of studying the effect of a phenyl substituent on the intramolecular photoredox reaction of 3-(hydroxymethyl)benzophenone (5) discovered in our laboratory. This latter compound was found to undergo a unimolecular (formal) intramolecular redox reaction upon photolysis in aqueous acid that results in clean reduction of the benzophenone ketone (to secondary alcohol) and oxidation of the alcohol to aldehyde. Three of the phenyl-substituted compounds with simple phenyl (7), p-methylphenyl (8), and p-methoxyphenyl (9) were found to undergo the acid-catalyzed intramolecular photoredox reaction with the observation that 9 also undergoes a residual photoredox reaction that is not acid-mediated and may involve initial photoinduced electron transfer, which is supported by LFP data. The m-methoxyphenyl (10) compound did not undergo the reaction. The trend in observed relative reactivity may be partially rationalized by examining changes in molecular orbital coefficients observed in the calculated HOMOs and LUMOs. The photoredox reaction has also been applied twice in succession in a single compound 11, demonstrating that the photoredox reaction may be useful for sequential photoredox reactions in a multifunctional compound.Key words: intramolecular photoredox, acid catalysis, meta effect, benzophenone photochemistry.
X-Ray structures and binding properties of molecular clips based on diethoxycarbonyl glycoluril
Authors: Zhou Bao H , Cao Li P , Yin Guo D , Gao M , Wu An X
Published: August 2007

The crystal structures of two molecular clips derived from diethoxycarbonyl glycoluril were reported. Their unique binding behavior towards hydroquinone, which is different from Nolte's clips (high affinity for resorcinol), has been characterized through 1H NMR and IR. Job-plot analyses provide good evidence of a 1:1 stoichiometry for the complexes.Key words: crystal structure, molecular clips, binding properties
Chromatographic enantiomer separation and circular dichroism (CD) spectra of three 4-endosubstituted-3,6-diphenyl-3,6-phenylphosphorylcyclohexenes
Authors: Hocking Martin B , Khan Aga Z-Q.
Published: August 2007

Three enantiomeric pairs of Diels–Alder adducts of 2,5-diphenylphosphole-1-oxide have been resolved by elution of each of the enantiomers with 95% ethanol from a swollen microcrystalline triacetylcellulose stationary phase. The degree of separation achieved in each case was confirmed by comparing the absorbance maximum of the UV spectrum of each separated enantiomer with that of a similar concentration of the relevant racemic mixture. The circular dichroism (CD) spectrum of each of the separated enantiomers was recorded, and spectral parameters are listed.Key words: enantiomer separations, three 4-endosubstituted phosphorus-bridged cyclohexenes (phosphanorbornenes), ethanol, microcrystalline triacetylcellulose.
EQUIVALENCE OF SYMMETRIC UNION DIAGRAMS
Authors: EISERMANN MICHAEL , LAMM CHRISTOPH
Published: August 2007

Motivated by the study of ribbon knots we explore symmetric unions, a beautiful construction introduced by Kinoshita and Terasaka 50 years ago. It is easy to see that every symmetric union represents a ribbon knot, but the converse is still an open problem. Besides existence it is natural to consider the question of uniqueness. In order to attack this question we extend the usual Reidemeister moves to a family of moves respecting the symmetry, and consider the symmetric equivalence thus generated. This notion being in place, we discuss several situations in which a knot can have essentially distinct symmetric union representations. We exhibit an infinite family of ribbon two-bridge knots each of which allows two different symmetric union representations.
A NOTE ON THE SHADOW COCYCLE INVARIANT OF A KNOT WITH A BASE POINT
Authors: SATOH S.
Published: August 2007

Fox's shadow p-colorings of a knot K define two kinds of Laurent polynomials, Φp(K) and [Formula: see text], as invariants of K. We prove that the equality [Formula: see text] holds for any knot K. Also we prove that, if the p-coloring number of K is equal to p2, then [Formula: see text] has the form [Formula: see text] for some N ∈ ℤp.
STATE MODELS FOR KNOT POLYNOMIALS AN INTRODUCTION
Authors: KAUFFMAN LOUIS H.
Published: August 2007

This paper is an unpublished version of a talk that the author gave in Brazil in 1987 at a meeting of the Brazilian Mathematical Society, while visiting Sostenes Lins in Recife, Brazil. The paper is an introduction to state models for link invariants, and it gives a surface-genus interpretation of the extreme terms in the bracket polynomial.
nPKCε, a P2Y2-R downstream effector in regulated mucin secretion from airway goblet cells
Authors: Ehre Camille , Zhu Yunxiang , Abdullah Lubna H. , Olsen John , Nakayama Keiichi I. , Nakayama Keiko , Messing Robert O. , Davis C. William
Published: August 2007

Airway goblet cell mucin secretion is controlled by agonist activation of P2Y2 purinoceptors, acting through Gq/PLC, inositol-1,4,5-trisphosphate (IP3), diacylglycerol, Ca2+ and protein kinase C (PKC). Previously, we showed that SPOC1 cells express cPKCα, nPKCδ, nPKCε, and nPKCη; of these, only nPKCδ translocated to the membrane in correlation with mucin secretion (Abdullah LH, Bundy JT, Ehre C, Davis CW. Am J Physiol Lung Physiol 285: L149–L160, 2003). We have verified these results and pursued the identity of the PKC effector isoform by testing the effects of altered PKC expression on regulated mucin release using SPOC1 cell and mouse models. SPOC1 cells overexpressing cPKCα, nPKCδ, and nPKCη had the same levels of ATPγS- and phorbol-1,2-myristate-13-acetate (PMA)-stimulated mucin secretion as the levels in empty retroviral vector expressing cells. Secretagogue-induced mucin secretion was elevated only in cells overexpressing nPKCε (14.6 and 23.5%, for ATPγS and PMA). Similarly, only SPOC1 cells infected with a kinase-deficient nPKCε exhibited the expected diminution of stimulated mucin secretion, relative to wild-type (WT) isoform overexpression. ATPγS-stimulated mucin secretion from isolated, perfused mouse tracheas was diminished in P2Y2-R null mice by 82% relative to WT mice, demonstrating the utility of mouse models in studies of regulated mucin secretion. Littermate WT and nPKCδ knockout (KO) mice had nearly identical levels of stimulated mucin secretion, whereas mucin release was nearly abolished in nPKCε KO mice relative to its WT littermates. We conclude that nPKCε is the effector isoform downstream of P2Y2-R activation in the goblet cell secretory response. The translocation of nPKCδ observed in activated cells is likely not related to mucin secretion but to some other aspect of goblet cell biology.
Leptin requires canonical migratory signaling pathways for induction of monocyte and macrophage chemotaxis
Authors: Gruen Marnie L. , Hao Mingming , Piston David W. , Hasty Alyssa H.
Published: August 2007

The growing worldwide obesity epidemic is frequently linked to an increased risk of developing diseases such as diabetes, cardiovascular disease, and cancer. These diseases are associated with the infiltration of macrophages in white adipose tissue (WAT), the artery wall, and tumors, respectively; and these macrophages likely contribute to disease progression and pathogenesis. Abdominal WAT, adipose tissue surrounding the heart and artery wall, as well as carcinoma cells, secrete many factors that could induce macrophage infiltration. Leptin is an adipocyte-secreted hormone, and deficiency of either leptin or its receptor has been shown to cause morbid obesity in animals and in humans. However, what is more commonly noted in human obesity is the presence of central leptin resistance leading to hyperleptinemia. As leptin receptors are present on macrophages, we hypothesized that leptin could act as a monocyte/macrophage chemoattractant. Our current study demonstrates: 1) leptin is a potent chemoattractant for monocytes and macrophages, inducing maximal chemotactic responses at 1 ng/ml; 2) leptin-mediated chemotaxis requires the presence of full-length leptin receptors on migrating cells; 3) leptin causes increased influx of intracellular calcium in macrophages; and 4) activation of janus kinase/signal transducers and activators of transduction (JAK/STAT), mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3K) pathways are all necessary for leptin-induced macrophage migration. Taken together, these data demonstrate that leptin is a potent monocyte/macrophage chemoattractant in vitro and that canonical cell motility machinery is activated upon macrophage exposure to leptin. These data have implications for the impact of hyperleptinemia on obesity-related pathophysiological conditions such as diabetes, cardiovascular disease, and cancer.
Electron microprobe analysis of rabbit ciliary epithelium indicates enhanced secretion posteriorly and enhanced absorption anteriorly
Authors: McLaughlin Charles W. , Zellhuber-McMillan Sylvia , Macknight Anthony D. C. , Civan Mortimer M.
Published: August 2007

The rate of aqueous humor formation sequentially across the pigmented (PE) and nonpigmented (NPE) ciliary epithelial cell layers may not be uniform over the epithelial surface. Because of the tissue's small size and complex geometry, this possibility cannot be readily tested by conventional techniques. Rabbit iris-ciliary bodies were divided, incubated, quick-frozen, cryosectioned, and freeze-dried for electron probe X-ray microanalysis of the elemental contents of the PE and NPE cells. We confirmed that preincubation with ouabain to block Na+,K+-ATPase increases Na+ and decreases K+ contents far more anteriorly than posteriorly. The anterior and posterior regions were the iridial portion of the primary ciliary processes and the pars plicata, respectively. Following interruption of gap junctions with heptanol, ouabain produced smaller changes in anterior PE cells, possibly reflecting higher Na+ or K+ permeability of anterior NPE cells. Inhibiting Na+ entry selectively with amiloride, benzamil, or dimethylamiloride reduced anterior effects of ouabain by ∼50%. Regional dependence of net secretion was also assessed with hypotonic stress, which stimulates ciliary epithelial cell regulatory volume decrease (RVD) and net Cl− secretion. In contrast to ouabain's actions, the RVD was far more marked posteriorly than anteriorly. These results suggest that 1) enhanced Na+ reabsorption anteriorly, likely through Na+ channels and Na+/H+ exchange, mediates the regional dependence of ouabain's actions; and 2) secretion may proceed primarily posteriorly, with secondary processing and reabsorption anteriorly. Stimulation of anterior reabsorption might provide a novel strategy for reducing net secretion.
Lysoplasmenylcholine increases neutrophil adherence to human coronary artery endothelial cells
Authors: White Maureen C. , Rastogi Prerna , McHowat Jane
Published: August 2007

We demonstrated previously that thrombin stimulation of human coronary artery endothelial cells (HCAEC) results in release of choline lysophospholipids [lysophosphatidylcholine (lysoPtdCho) and lysoplasmenylcholine (lysoPlsCho)]. These amphiphilic metabolites have been implicated in arrhythmogenesis following the onset of myocardial ischemia, but studies examining their direct effects on the vasculature remain limited. We and others have shown that thrombin and lysoPtdCho can increase cell surface adhesion molecules and adherence of circulating inflammatory cells to the endothelium. This study supports our hypothesis that these changes may be mediated, at least in part, by lysoPlsCho, thus implicating this metabolite as an inflammatory mediator in the coronary vasculature and a modulator of the progression of atherosclerosis. Apical stimulation of HCAEC with thrombin resulted in the production and release of choline lysophospholipids from the apical surface of the HCAEC monolayer. Basolateral stimulation had no effect on choline lysophospholipid production or release from either the apical or basolateral surface of the HCAEC monolayer. Incubation of HCAEC with lysoPlsCho or lysoPtdCho resulted in similar increases in HCAEC surface expression of P-selectin and E-selectin. Furthermore, lysoPlsCho increased cell surface expression of P-selectin, E-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 with a time course similar to that of thrombin stimulation. Increased presence of cell surface adhesion molecules may contribute to the significant increase in adherence of neutrophils to either thrombin- or lysoPlsCho-stimulated HCAEC. These results demonstrate that the presence of thrombin at sites of vascular injury in the coronary circulation, resulting in increased choline lysophospholipid release from the HCAEC apical surface, has the potential to propagate vascular inflammation by upregulation of adhesion molecules and recruitment of circulating inflammatory cells to the endothelium.