bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the Large June 1975 Meteoroid Storm on Earth's Ionosphere
Authors: Kaufmann P. , Kuntz V. L. R. , Leme N. M. Paes , Piazza L. R. , Boas J. W. S. Vilas , Brecher K. , Crouchley J.
Published: October 2006

The June 1975 meteoroid storm detected on the moon by the Apollo seismometers was the largest ever observed. Reexamination of radio data taken at that time showed that the storm also produced pronounced disturbances on Earth, which were recorded as unique phase anomalies on very low frequency (VLF) radio propagation paths in the low terrestrial ionosphere. Persistent effects were observed for the major storm period (20 to 30 June 1975), including reductions in the diurnal phase variation, advances in the nighttime and daytime phase levels, and reductions in the sunset phase delay rate. Large nighttime phase advances, lasting a few hours, were detected on some days at all VLF transmissions, and for the shorter propagation path they were comparable to solar Lyman alpha daytime ionization. Ion production rates attributable to the meteor storm were estimated to be about 0.6 to 3.0 ions per centimeter cubed per second at the E and D regions, respectively. The storm was a sporadic one with a radiant (that is, the point of apparent origin in the sky) located in the Southern Hemisphere, with a right ascension 1 to 2 hours larger than the sun's right ascension.
Activation of Bacterial Porin Gene Expression by a Chimeric Signal Transducer in Response to Aspartate
Authors: Utsumi Ryutaro , Brissette Renee E. , Rampersaud Arfaan , Forst Steven A. , Oosawa Kenji , Inouye Masayori
Published: October 2006

The Tar chemoreceptor of
Escherichia coli
is a membrane-bound sensory protein that facilitates bacterial chemotaxis in response to aspartate. The EnvZ molecule has a membrane topology similar to Tar and is a putative osmosensor that is required for osmoregulation of the genes for the major outer membrane porin proteins, OmpF and OmpC. The cytoplasmic signaling domain of Tar was replaced with the carboxyl portion of EnvZ, and the resulting chimeric receptor activated transcription of the
ompC
gene in response to aspartate. The activation of ompC by the chimeric receptor was absolutely dependent on OmpR, a transcriptional activator for
ompF
and
ompC
.
Faults in the Mojave Desert, California, as Revealed on Enhanced Landsat Images
Authors: Ford J. P. , Dokka R. K. , Crippen R. E. , Blom R. G.
Published: October 2006

Previously unknown strike-slip and normal faults in the central and eastern Mojave Desert have been revealed on Landsat Thematic Mapper images enhanced by four-component processing. This method provides color images on which lithologies are discriminated by their contrasting absorption and reflection, primarily at infrared wavelengths and particularly with regard to their ferric iron, ferrous iron, and hydroxyl contents, while retaining landform depiction. These discriminants represent a new type of geophysical display for geologic mapping in regions of well-exposed bedrock. Faults are revealed on the images by abrupt spectral and textural contrasts that coincide with aligned topographic features. The newly discovered faults form part of an extensive regional network of right shear that connects faults in the Death Valley region with the San Andreas fault system. They support a heterogeneous strain model for late Cenozoic tectonic evolution of the region. Regional structural relations indicate a westward migration of the locus of strain through time. Some of the newly identified faults bound blocks that have experienced contrasting rotational histories since early Miocene time.
Vertical Distribution of Water in the Atmosphere of Venus: A Simple Thermochemical Explanation
Authors: Lewis John S. , Grinspoon David H.
Published: October 2006

Several lines of evidence concerning the vertical abundance profile of water in the atmosphere of Venus lead to strikingly unusual distributions (the water vapor abundance decreases sharply in the immediate vicinity of the surface) or to serious conflicts in the profiles (different infrared bands suggest water abundances that are discrepant by a factor of 2.5 to 10). These data sets can be reconciled if (i) water molecules associate with carbon dioxide and sulfur trioxide to make gaseous carbonic acid and sulfuric acid in the lower atmosphere, and (ii) the discrepant 0.94-micrometer water measurements are due to gaseous sulfuric acid, requiring it to be a somewhat stronger absorber than water vapor in this wavelength region. A mean total water abundance of 50 ± 20 parts per million and a near-surface free water vapor abundance of 10 ± 4 parts per million are derived.
Simulation of Tsunamis from Great Earthquakes on the Cascadia Subduction Zone
Authors: Ng Max K.-F. , Leblond Paul H. , Murty Tad S.
Published: October 2006

Large earthquakes occur episodically in the Cascadia subduction zone. A numerical model has been used to simulate and assess the hazards of a tsunami generated by a hypothetical earthquake of magnitude 8.5 associated with rupture of the northern sections of the subduction zone. Wave amplitudes on the outer coast are closely related to the magnitude of sea-bottom displacement (5.0 meters). Some amplification, up to a factor of 3, may occur in some coastal embayments. Wave amplitudes in the protected waters of Puget Sound and the Strait of Georgia are predicted to be only about one fifth of those estimated on the outer coast.
Free Radicals Within the Antarctic Vortex: The Role of CFCs in Antarctic Ozone Loss
Authors: Anderson J. G. , Toohey D. W. , Brune W. H.
Published: October 2006

How strong is the case linking global release of chlorofluorocarbons to episodic disappearance of ozone from the Antarctic stratosphere each austral spring? Three lines of evidence defining a link are (i) observed containment in the vortex of ClO concentrations two orders of magnitude greater than normal levels; (ii) in situ observations obtained during ten high-altitude aircraft flights into the vortex as the ozone hole was forming that show a decrease in ozone concentrations as ClO concentrations increased; and (iii) a comparison between observed ozone loss rates and those predicted with the use of absolute concentrations of ClO and BrO, the rate-limiting radicals in an array of proposed catalytic cycles. Recent advances in our understanding of the kinetics, photochemistry, and structural details of key intermediates in these catalytic cycles as well as an improved absolute calibration for ClO and BrO concentrations at the temperatures and pressures encountered in the lower antarctic stratosphere have been essential for defining the link.
Venus Southern Hemisphere: Geologic Character and Age of Terrains in the Themis-Alpha-Lada Region
Authors: Campbell D. B. , Senske D. A. , Head J. W. , Hine A. A. , Fisher P. C.
Published: October 2006

Arecibo high-resolution radar images of the southern hemisphere of Venus extending to 78°S show that the surface of the Themis-Alpha-Lada region is characterized by linear deformation zones with volcanoes and corona-like features and by regional volcanic deposits (primarily plains, small shields, and large edifices). Large-scale areal deformation is limited to the tessera of Alpha Regio. Lada Terra, in the southern high latitudes, contains several large coronae, in contrast to Ishtar Terra in the northern high latitudes. The density of craters of possible impact origin is somewhat lower than that observed in the Venera 15 and 16 coverage; these data extend to 43 percent of the areas of the surface of Venus with ages of less than about 1 billion years.
Potassium in Clinopyroxene Inclusions from Diamonds
Authors: Harlow George E. , Veblen David R.
Published: October 2006

Analytical transmission electron microscopy, electron microprobe analyses, and single-crystal x-ray diffraction data support the conclusion that high potassium contents, up to 1.5 weight percent K
2
O, of some diopside and omphacite inclusions from diamonds represent valid clinopyroxene compositions with K in solid solution. This conclusion contradicts the traditional view of pyroxene crystal chemistry, which holds that K is too large to be incorporated in the pyroxene structure. These diopside and omphacite inclusions have a high degree of crystal perfection and anomalously large unit-cell volumes, and a defect-free structure is observed in K-bearing regions when imaged by transmission electron microscopy. These observations imply that clinopyroxene can be a significant host for K in the mantle and that some clinopyroxene inclusions and their diamond hosts may have grown in a highly K-enriched environment.
Point Mutational Inactivation of the Retinoblastoma Antioncogene
Authors: Horowitz Jonathan M. , Yandell David W. , Park Sang-Ho , Canning Susan , Whyte Peter , Buchkovich Karen , Harlow Ed , Weinberg Robert A. , Dryja Thaddeus P.
Published: October 2006

The retinoblastoma (Rb) antioncogene encodes a nuclear phosphoprotein, p105-Rb, that forms protein complexes with the adenovirus E1A and SV40 large T oncoproteins. A novel, aberrant Rb protein detected in J82 bladder carcinoma cells was not able to form a complex with E1A and was less stable than p105-Rb. By means of a rapid method for the detection of mutations in Rb mRNA, this defective Rb protein was observed to result from a single point mutation within a splice acceptor sequence in J82 genomic DNA. This mutation eliminates a single exon and 35 amino acids from its encoded protein product.
Correction: Selection of Variable-Joining Region Combinations in the T Cell Receptor
Authors: Roth Matthew E. , Lacy Michael J. , McNeil Leslie Klis , Kranz David M.
Published: October 2006

We wish to make a correction concerning our 9 September 1988 report "Selection of variable-joining [VJ] region combinations in the α chain of the T cell receptor". We have discovered that the V
58
J
3
isolates actually contain part of the 3′ heptamer-spacer sequence from the V
58
germline and thus these do not, in fact, contain a joining segment. Because these isolates exhibit diversity at the coding-signal junction, we incorrectly assumed that they were bona fide VJ transcripts. At this time we do not know whether the junctional bases are nongermline elements introduced at the coding-signal joints, or whether transcripts from such nonrearranged V
α
genes might serve some function. Transcripts from nonrearranged gamma genes have recently been reported, and these are inducible by interleukin-3.

We would also like to comment on the observation that the V
58
J
58
isolates do not contain diversity at the VJ joint. This lack of diversity, in contrast to that of all other VJ isolates from our laboratory, has raised the question of whether these may have been derived, as a polymerase chain reaction contaminant, from the α chain gene isolated from CTL 2C. At this time we do not have a definitive answer.

Despite the error in our analysis of the V
58
J
3
isolates, the main tenet of our report (that is, the preferential association and expression of particular VJ combinations) holds true. Thus, the J
1
and J
2
isolates (figures 1 and 3) and only a few other J segments have been found to be expressed as the predominant V
58
transcripts.
Periodic Hot-Spot Distribution on Io
Authors: Yamaji Atsushi
Published: October 2006

The Jovian satellite Io has active volcanic hot spots. The point-to-point correlation of the hot-spot distribution indicates that the hot spots preferentially make chains. The arrangement of the chains is periodic with a typical spacing of 120 kilometers. The chains exhibit concordant trends with stresses imposed by the tidal deflection of the lithosphere, suggesting that the hot spots are formed along fissures in the lithosphere. The typical spacing may be controlled by lithosphere thickness.
Foreign Direct Investment in the United States and U.S. Interests
Authors: Graham Edward M.
Published: October 2006

Foreign direct investment entered the United States at unprecedented rates during the second half of the 1980s. The result has been much higher levels of foreign ownership of U.S. economic activities than those to which the nation has been accustomed. The reasons for this investment include loss of competitiveness of U.S. firms compared to international rivals as well as attractions to foreign investors of the United States itself. The economic effects of greater levels of foreign ownership are generally positive, although some problems with levels of competition could ensue. National security considerations might cause the United States to place some restrictions on this investment, but other restrictions at the present time appear to be unwarranted.
Template-Directed Oligomerization Catalyzed by a Polynucleotide Analog
Authors: Visscher J. , Bakker C. G. , van der Woerd R. , Schwartz A. W.
Published: October 2006

A pyrophosphate-linked analog of polycytidylic acid has been synthesized and shown to catalyze the oligomerization of the complementary monomer 2′-deoxyguanosine 3′,5′-bisphosphoimidazolide. Analogs of polynucleotides are of interest in studies of the origins of life as possible precursors of the first RNA molecules. These results demonstrate that such molecules are capable of serving as templates for further synthesis.
Vaccine Protection of Chimpanzees Against Challenge with HIV-1-Infected Peripheral Blood Mononuclear Cells
Authors: Fultz Patricia N. , Nara Peter , Barre-Sinoussi Francoise , Chaput Agnes , Greenberg Michael L. , Muchmore Elizabeth , Kieny Marie-Paule , Girard Marc
Published: October 2006

Because human immunodeficiency virus (HIV) can be transmitted as cell-free virus or as infected cells (cell-associated virus), vaccines must protect against infection by both viral forms. Vaccine-mediated protection of nonhuman primates against low doses of cell-free HIV-1, HIV-2, or simian immunodeficiency virus (SIV) has been demonstrated. It is now shown that multiple immunizations of chimpanzees with HIV-1 antigens protected against infection with cell-associated virus. Protection can persist for extended periods (one animal had not been exposed to viral antigens for 1 year before challenge). These results show that it is possible to elicit long-lasting protective immunity against cell-associated HIV-1.
Function of a Bacterial Activator Protein That Binds to Transcriptional Enhancers
Authors: Popham David L. , Szeto Daniel , Keener John , Kustu Sydney
Published: October 2006

The nitrogen regulatory (NtrC) protein of enteric bacteria, which binds to sites that have the properties of transcriptional enhancers, is known to activate transcription by a form of RNA polymerase that contains the NtrA protein (σ
54
) as sigma factor (referred to as σ
54
-holoenzyme). In the presence of adenosine triphosphate, the NtrC protein catalyzes isomerization of closed recognition complexes between σ
54
-holoenzyme and the
glnA
promoter to open complexes in which DNA in the region of the transcription start site is locally denatured. NtrC is not required subsequently for maintenance of open complexes or initiation of transcription.
Mesosiderite Clasts with the Most Extreme Positive Europium Anomalies Among Solar System Rocks
Authors: Mittlefehldt David W. , Rubin Alan E. , Davis Andrew M.
Published: October 2006

Pigeonite-plagioclase gabbros that occur as clasts in mesosiderites (brecciated stony-iron meteorites) show extreme fractionations of the rare-earth elements (REEs) with larger positive europium anomalies than any previously known for igneous rocks from the Earth, moon, or meteorite parent bodies and greater depletions of light REEs relative to heavy REEs than known for comparable cumulate gabbros. The REE pattern for merrillite in one of these clasts is depleted in light REEs and has a large positive europium anomaly as a result of metamorphic equilibration with the silicates. The extreme REE ratios exhibited by the mesosiderite clasts demonstrate that multistage igneous processes must have occurred on some asteroids in the early solar system. Melting of the crust by large-scale impacts or electrical induction from an early T-Tauri-phase sun may be responsible for these processes.
Trefoil Knotting Revealed by Molecular Dynamics Simulations of Supercoiled DNA
Authors: Schlick Tamar , Olson Wilma K.
Published: October 2006

Computer simulations of the supercoiling of DNA, largely limited to stochastic search techniques, can offer important information to complement analytical models and experimental data. Through association of an energy function, minimum-energy supercoiled conformations, fluctuations about these states, and interconversions among forms may be sought. In theory, the observation of such large-scale conformational changes is possible, but modeling and numerical considerations limit the picture obtained in practice. A new computational approach is reported that combines an idealized elastic energy model, a compact B-spline representation of circular duplex DNA, and deterministic minimization and molecular dynamics algorithms. A trefoil knotting result, made possible by a large time-step dynamics scheme, is described. The simulated strand passage supports and details a supercoiled-directed knotting mechanism. This process may be associated with collective bending and twisting motions involved in supercoiling propagation and interwound branching. The results also demonstrate the potential effectiveness of the Langevin/ implicit-Euler dynamics scheme for studying biomolecular folding and reactions over biologically interesting time scales.
Detection of Trace Molecular Species Using Degenerate Four-Wave Mixing
Authors: Farrow Roger L. , Rakestraw David J.
Published: October 2006

Spectroscopies that make use of laser light have provided an important tool to modern researchers for the nonintrusive analysis of chemical systems. The strengths and limitations of these spectroscopic techniques often determine the viability of scientific investigations. The unique properties of degenerate four-wave mixing, a nonlinear optical technique, have recently been found to provide powerful capabilities for a wide range of applications.
Astronomers Meet in Phoenix, Recount a Stellar Year
Authors: Flam Faye
Published: October 2006

Despite a tightening of the National Aeronautics and Space Administration's budget and the trouble with the Hubble Space Telescope, astronomers were starry-eyed over their latest findings, presented at the major annual meeting of the American Astronomical Society, (AAS) January 3 to 7. New images and measurements of stars, galaxies, cosmic microwaves, and mysterious gamma rays, along with an exciting nova explosion, made it a bright year for those working with existing orbiting satellites and ground-based telescopes, though uncertain funding clouds the future.
Live Iron-60 in the Early Solar System
Authors: Shukolyukov A. , Lugmair G. W.
Published: October 2006

Isotopic analyses of nickel in samples from the differentiated meteorite Chervony Kut revealed the presence of relative excesses of
60
Ni ranging from 2.4 up to 50 parts per 10
4
. These isotopic excesses are from the decay of the now extinct short-lived nuclide
60
Fe and provide clear evidence for the existence of
60
Fe over large scales in the early solar system. Not only was
60
Fe present at the time of melting and differentiation (that is, Fe-Ni fractionation) of the parent body of Chervony Kut but also later at the time when basaltic magma solidified at or near the surface of the planetesimal. The inferred abundance of
60
Fe suggests that its decay alone could have provided sufficient heat to melt small (diameters of several hundred kilometers) planetary bodies shortly after their accretion.
Record Low Global Ozone in 1992
Authors: Gleason J. F. , Bhartia P. K. , Herman J. R. , McPeters R. , Newman P. , Stolarski R. S. , Flynn L. , Labow G. , Larko D. , Seftor C. , Wellemeyer C. , Komhyr W. D. , Miller A. J. , Planet W.
Published: October 2006

The 1992 global average total ozone, measured by the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus-7 satellite, was 2 to 3 percent lower than any earlier year observed by TOMS (1979 to 1991). Ozone amounts were low in a wide range of latitudes in both the Northern and Southern hemispheres, and the largest decreases were in the regions from 10°S to 20°S and 10°N to 60°N. Global ozone in 1992 is at least 1.5 percent lower than would be predicted by a statistical model that includes a linear trend and accounts for solar cycle variation and the quasi-biennial oscillation. These results are confirmed by comparisons with data from other ozone monitoring instruments: the SBUV/2 instrument on the NOAA-11 satellite, the TOMS instrument on the Russian Meteor-3 satellite, the World Standard Dobson Instrument 83, and a collection of 22 ground-based Dobson instruments.
Early Cambrian Ostracode Larvae with a Univalved Carapace
Authors: Zhang Xi-guang , Pratt Brian R.
Published: October 2006

Phosphatized univalves, recovered from the Lower Cambrian (∼530 million years old) Qiongzhusi Formation in southern China, are recognized as early instars belonging to bradoriid ostracodes whose later instars are bivalved. The univalved form is the primitive larval character for shell-secreting crustaceans, although most post-Cambrian ostracodes bypassed this developmental phase. The univalved-bivalved transition during early ontogeny represents an important evolutionary event in ostracodes, with implications for crustacean classification, and implies that the ostracode ancestor achieved this bivalved capacity before the appearance of mineralized skeletons during the "Cambrian explosion."
Electrophysiologic Responses in Hamster Superior Colliculus Evoked by Regenerating Retinal Axons
Authors: Keirstead S. A. , Rasminsky M. , Fukuda Y. , Carter D. A. , Aguayo A. J. , Vidal-Sanz M.
Published: October 2006

Autologous peripheral nerve grafts were used to permit and direct the regrowth of retinal ganglion cell axons from the eye to the ipsilateral superior colliculus of adult hamsters in which the optic nerves had been transected within the orbit. Extracellular recordings in the superior colliculus 15 to 18 weeks after graft insertion revealed excitatory and inhibitory postsynaptic responses to visual stimulation. The finding of light-induced responses in neurons in the superficial layers of the superior colliculus close to the graft indicates that axons regenerating from axotomized retinal ganglion cells can establish electrophysiologically functional synapses with neurons in the superior colliculus of these adult mammals.
Unusual Pattern of Accumulation of mRNA Encoding EGF-Related Protein in Sea Urchin Embryos
Authors: Yang Qing , Angerer Lynne M. , Angerer Robert C.
Published: October 2006

A sea urchin (
Strongylocentrotus purpuratus
) messenger RNA encoding a protein (SpEGF2) related to epidermal growth factor (EGF) was identified. The full-length complementary DNA sequence predicts a protein with an unusually simple structure, including four tandem EGF-like repeats and a hydrophobic leader, but lacking a potential transmembrane domain. Sequence similarities suggest that the peptides are homologous to two peptides from a different sea urchin species, which cause a classic developmental defect, exogastrulation, when added to the seawater outside of embryos. The SpEGF2 messenger RNA begins to accumulate at blastula stage, and in pluteus larvae it is distributed in discrete regions of ectoderm that are not congruent with known histological borders. One region corresponds to that expressing the homeodomain-containing protein, SpHbox1. The structure of the SpEGF2 protein and the pattern of accumulation of its messenger RNA suggest that it may have important functions as a secreted factor during development of sea urchin embryos.
Hybrid Dysgenesis in
D. melanogaster
Is Not a General Release Mechanism for DNA Transpositions
Authors: Woodruff R. C. , Blount J. L. , Thompson J. N.
Published: October 2006

Many spontaneous mutations are caused by the insertion or excision of DNA elements. Since most mutations are deleterious, evolution should favor a mechanism for genetically controlling the rate of movement of transposable elements in most, if not all, organisms. In
Drosophila melanogaster
a syndrome of correlated genetic changes, including mutation, chromosome breakage, and sterility, is observed in the hybrid progeny of crosses between different strains. This syndrome, which is termed hybrid dysgenesis, results from the movement of P-DNA elements. What is not clear is whether the movement of other types of transposable elements is under the same coordinated control. In this study the ability of hybrid dysgenesis to increase the rate of excision of 12 DNA elements at 16 mutant alleles and to induce insertion-bearing mutations to change to other mutant states was tested. The data show that hybrid dysgenesis caused by P-element transpositions does not act as a general stimulus for the movement of other Drosophila transposable elements.
Tandem Array of Human Visual Pigment Genes at Xq28
Authors: Vollrath Douglas , Nathans Jeremy , Davis Ronald W.
Published: October 2006

Unequal crossing-over within a head-to-tail tandem array of the homologous red and green visual pigment genes has been proposed to explain the observed variation in green-pigment gene number among individuals and the prevalence of red-green fusion genes among color-blind subjects. This model was tested by probing the structure of the red and green pigment loci with long-range physical mapping techniques. The loci were found to constitute a gene array with an approximately 39-kilobase repeat length. The position of the red pigment gene at the 5′ edge of the array explains its lack of variation in copy number. Restriction maps of the array in four individuals who differ in gene number are consistent with a head-to-tail configuration of the genes. These results provide physical evidence in support of the model and help to explain the high incidence of color blindness in the human population.
Abnormalities in Structure and Expression of the Human Retinoblastoma Gene in SCLC
Authors: Harbour J. William , Lai Shinn-Liang , Whang-Peng Jacqueline , Gazdar Adi F. , Minna John D. , Kaye Frederic J.
Published: October 2006

Small cell lung cancer (SCLC) has been associated with loss of heterozygosity at several distinct genetic loci including chromosomes 3p, 13q, and 17p. To determine whether the retinoblastoma gene (
Rb
) localized at 13q14, might be the target of recessive mutations in lung cancer, eight primary SCLC tumors and 50 cell lines representing all major histologic types of lung cancer were examined with the
Rb
complementary DNA probe. Structural abnormalities within the
Rb
gene were observed in 1/8 (13%) primary SCLC tumors, 4/22 (18%) SCLC lines, and 1/4 (25%) pulmonary carcinoid lines (comparable to the 20 to 40% observed in retinoblastoma), but were not detected in other major types of lung cancer.
Rb
messenger RNA expression was absent in 60% of the SCLC lines and 75% of pulmonary carcinoid lines, including all samples with DNA abnormalities. In contrast,
Rb
transcripts were found in 90% of non-SCLC lung cancer lines and in normal human lung. The finding of abnormalities of the
Rb
gene in SCLC and pulmonary carcinoids (both neuroendocrine tumors) suggests that this gene may be involved in the pathogenesis of a common adult malignancy.
Somatostatin Augments the M-Current in Hippocampal Neurons
Authors: Moore Scott D. , Madamba Samuel G. , Joëls Marian , Siggins George R.
Published: October 2006

Immunocytochemical and electrophysiological evidence suggests that somatostatin may be a transmitter in the hippocampus. To characterize the ionic mechanisms underlying somatostatin effects, voltage-clamp and current-clamp studies on single CA1 pyramidal neurons in the hippocampal slice preparation were performed. Both somatostatin-28 and somatostatin-14 elicited a steady outward current and selectively augmented the noninactivating, voltage-dependent outward potassium current known as the M-current. Since the muscarinic cholinergic agonists carbachol and muscarine antagonized this current, these results suggest a reciprocal regulation of the M-current by somatostatin and acetylcholine.
Determination of Junction Avidity of Cytolytic T Cell and Target Cell
Authors: Sung Kuo-Li , Sung Lanping A. , Crimmins Mary , Burakoff Steven J. , Chien Shu
Published: October 2006

A direct measurement of the avidity of the junction between a cytotoxic T lymphocyte and its target cell was achieved by using a biophysical approach. A micromanipulation technique was used to determine the force required to separate a cytotoxic T cell (human clone F1, with specificity for HLA-DRw6) from its specific target cell (JY: HLA-A2, -B7, -DR4, w6) prior to delivery of the lethal hit. The force required to separate the F1-JY pair is 1.5 × 10
4
dynes per square centimeter. This junction avidity for F1-JY pairs is 6 to 13 times greater than that for F1-F1 and JY-JY pairs; the F1-JY conjugate requires a stronger separating force and is more easily rejoined than the homologous cell pairs. This study provides an estimate of the avidity of cytotoxic T cells for their target cells and insights into the biophysical correlates of the molecular complexes formed in the interaction of cytotoxic T cells and their targets during the cytotoxic process.
Laser-Stimulated Luminescence Used to Measure X-ray Diffraction of a Contracting Striated Muscle
Authors: Amemiya Yoshiyuki , Wakabayashi Katsuzo , Tanaka Hidehiro , Ueno Yutaka , Miyahara Junji
Published: October 2006

An integrating x-ray area detector that operates on the basis of laser-stimulated luminescence was used in a diffraction study of muscle contraction. The area detector has a dynamic range of 1 to 10
5
, a sensitivity about 60 times greater with approximately 1/300 as much fog background as x-ray film. It is erasable and reusable but, like film, can integrate at a practically unlimited counting rate. The high sensitivity and wide dynamic range of the detector resulted in a sufficient reduction in the exposure time to make possible the recording of a clear x-ray diffraction pattern, with up to 2.0-nanometer axial spacing, from a contracting frog skeletal muscle in as little as 10 seconds with synchrotron radiation. During the isometric contraction of the muscle, most of the actin diffraction lines increased in intensity without noticeable changes in their peak positions. Changes also occurred in diffraction intensities from the myosin heads. The results indicate that during contraction the structure of the actin filaments differs from that in the rigor state, suggesting a possible structural change in the actin subunits themselves; the myosin heads during contraction retain the axial periodicity of the myosin filament and become aligned in a more perpendicular manner to the actin filaments.
Direct Visualization of Organelle Movement Along Actin Filaments Dissociated from Characean Algae
Authors: Kachar Bechara
Published: October 2006

A system has been developed in which organelle transport can be studied without the influence of an organized cellular cytoplasm. Binding and continuous unidirectional movement of organelles along isolated cellular transport cables were directly visualized by video light microscopy after the dissociation of the cytoplasm of characean algae cells in a Ca
2+
-free buffer containing adenosine triphosphate. Individual organelles had more than one attachment site and moved at mean rates of 11.2 or 62.1 micrometers per second along multiple parallel pathways on each cable. Electron microscopy of these cables after direct freezing demonstrated that they consist of compact bundles of actin filaments. Under these conditions, characteristics of organelle movement should reflect directly the underlying molecular processes of binding and force generation.
Widespread Occurrence in Frogs and Toads of Skin Compounds Interacting with the Ouabain Site of Na
+
, K
+
-ATPase
Authors: Flier Jeffrey , Edwards Michael W. , Daly John W. , Myers Charles W.
Published: October 2006

Amphibians of the family Bufonidae contain high levels of skin compounds that both inhibit Na
+
- and K
+
-dependent adenosinetriphosphatase and antagonize the binding of ouabain to the enzyme. In species of Bufo and Atelopus, these compounds are relatively nonpolar bufodienolides, whereas Dendrophryniscus and Melanophryniscus contain more polar compounds of unknown structure. Skin extracts from 30 of 48 species of frogs representing an additional eight families contained relatively low levels of compounds that inhibit binding of ouabain to Na
+
,K
+
-adenosinetriphosphatase. The widespread occurrence of low levels of inhibitory compounds is consonant with a role for these compounds as physiological regulators of Na
+
,K
+
-adenosinetriphosphatase in amphibian skin; high levels in the Bufonidae probably also serve as a defense against some predators.
Intracellular Translocation of Iodine-125-Labeled Insulin: Direct Demonstration in Isolated Hepatocytes
Authors: Gorden P. , Carpentier J.-L. , Freychet P. , LeCam A. , Orci L.
Published: October 2006

Insulin labeled with iodine-125 binds to receptors on isolated rat hepatocytes. At low temperatures initial binding is restricted to the plasma membrane as detected by direct quantitative autoradiographic analysis with the electron microscope. With increasing time and temperature of incubation there is a systematic and progressive translocation of autoradiographic grains to a highly limited area of the cell periphery representing no more than 15 percent of the radius of the cell.
Corticotropin Releasing Factor Decreases Postburst Hyperpolarizations and Excites Hippocampal Neurons
Authors: Aldenhoff J. B. , Gruol D. L. , Rivier J. , Vale W. , Siggins G. R.
Published: October 2006

Corticotropin releasing factor in concentrations of 15 to 250 nanomoles per liter increased the spontaneous discharge frequency and decreased the size of hyperpolarizations after burst discharges in CA1 and CA3 pyramidal neurons of rat hippocampal slices. Concentrations greater than 250 nanomoles per liter also depolarized the cells. These excitatory actions of corticotropin releasing factor may involve a novel calcium-dependent process.
Inner Ear: Dye Injection Reveals Peripheral Origins of Specific Sensitivities
Authors: Lewis Edwin R. , Baird Richard A. , Leverenz Ellen L. , Koyama Hironori
Published: October 2006

In the American bullfrog (
Rana catesbeiana
) tracing of functionally identified, dye-filled fibers of the eighth cranial nerve to their peripheral origins has provided the first precise functional overlays for the microstructural maps of inner-ear sensory surfaces.
Deletion of the Paired α5(IV) and α6(IV) Collagen Genes in Inherited Smooth Muscle Tumors
Authors: Zhou Jing , Mochizuki Toshio , Smeets Hubert , Antignac Corinne , Laurila Pekka , de Paepe Anne , Tryggvason Karl , Reeders Stephen T.
Published: October 2006

The gene encoding α6(IV) collagen,
COL4A6
, was identified on the human X chromosome in a head-to-head arrangement and within 452 base pairs of the α5(IV) collagen gene,
COL4A5
. In earlier studies, intragenic deletions of
COL4A5
were detected in a subset of patients with Alport syndrome (AS), a hereditary defect of basement membranes. In some families, AS cosegregates with diffuse leiomyomatosis (DL), a benign smooth muscle tumor diathesis. Here it is shown that patients with AS-DL harbor deletions that disrupt both
COL4A5
and
COL4A6
. Thus, type IV collagen may regulate smooth muscle differentiation and morphogenesis.
Ras-Independent Growth Factor Signaling by Transcription Factor Tyrosine Phosphorylation
Authors: Silvennoinen Olli , Schindler Christian , Schlessinger Joseph , Levy David E.
Published: October 2006

Interferons induce transcriptional activation through tyrosine phosphorylation of the latent, cytoplasmic transcription factor interferon-stimulated gene factor-3 (ISGF-3). Growth factors and cytokines were found to use a similar pathway: The 91-kilodalton subunit of ISGF-3 was activated and tyrosine phosphorylated in response to epidermal growth factor (EGF), platelet-derived growth factor, and colony stimulating factor-1. The tyrosine phosphorylated factor acquired DNA binding activity and accumulated in nuclei. Activation required the major sites for autophosphorylation on the EGF receptor that bind Src homology region 2 domain-containing proteins implicated in Ras activation. However, activation of this factor was independent of the normal functioning of Ras.
Reversible Binding of Nitric Oxide by a Salivary Heme Protein from a Bloodsucking Insect
Authors: Ribeiro José M. C. , Hazzard Jo M. H. , Nussenzveig Roberto H. , Champagne Donald E. , Walker F. Ann
Published: October 2006

The bloodsucking bug
Rhodnius prolixus
has a salivary vasodilator, previously characterized as a nitrovasodilator, with salivary smooth muscle-relaxing and antiplatelet activity.
Rhodnius
salivary glands are bright red owing to the abundance of heme proteins. Electron paramagnetic resonance and optical spectroscopic experiments indicated that the salivary vasodilator is a nitrosylheme protein with an Fe(III) heme that binds nitric oxide (NO) reversibly. Dilution of the protein in neutral pH promoted NO release. This protein thus appears to be the NO carrier that helps
R. prolixus
to feed on blood.
Molecular Mapping and Detoxification of the Lipid A Binding Site by Synthetic Peptides
Authors: Rustici Alessandro , Velucchi Massimo , Faggioni Raffaella , Sironi Marina , Ghezzi Pietro , Quataert Sally , Green Bruce , Porro Massimo
Published: October 2006

Endotoxin [lipopolysaccharide (LPS)], the major antigen of the outer membrane of Gram-negative bacteria, consists of a variable-size carbohydrate chain that is covalently linked to
N
,
O
-acylated β-1,6-D-glucosamine disaccharide 1,4′-bisphosphate (lipid A). The toxic activity of LPS resides in the lipid A structure. The structural features of synthetic peptides that bind to lipid A with high affinity, detoxify LPS in vitro, and prevent LPS-induced cytokine release and lethality in vivo were defined. The binding thermodynamics were comparable to that of an antigen-antibody reaction. Such synthetic peptides may provide a strategy for prophylaxis and treatment of LPS-mediated diseases.
Hypermetabolism of Fat in V1a Vasopressin Receptor Knockout Mice
Authors: Hiroyama Masami , Aoyagi Toshinori , Fujiwara Yoko , Birumachi Junichi , Shigematsu Yosuke , Kiwaki Kohji , Tasaki Ryuji , Endo Fumio , Tanoue Akito
Published: October 2006

[Arg8]Vasopressin (AVP) has an antilipolytic action on adipocytes, but little is known about the mechanisms involved. Here, we examined the involvement of the V1a receptor in the antilipolytic effect of AVP using V1a receptor-deficient (V1aR−/−) mice. The levels of blood glycerol were increased in V1aR−/− mice. The levels of ketone bodies, such as acetoacetic acid and 3-hydroxybutyric acid, the products of the lipid metabolism, were increased in V1aR−/− mice under a fasting condition. Triacylglyceride and free fatty acid levels in blood were decreased in V1aR−/− mice. Furthermore, measurements with tandem mass spectrometry determined that carnitine and acylcarnitines in serum, the products of β-oxidation, were increased in V1aR−/− mice. Most acylcarnitines were increased in V1aR−/− mice, especially in the case of 2-carbon (C2), C10:1, C10, C14:1, C16, C18:1, and hydroxy-18:1-carbon (OH-C18:1)-acylcarnitines under feeding rather than under fasting conditions. The analysis of tissue C2-acylcarnitine level showed that β-oxidation was promoted in muscle under the feeding condition and in liver under the fasting condition. An in vitro assay using brown adipocytes showed that the cells of V1aR−/− mice were more sensitive to isoproterenol for lipolysis. These results suggest that the lipid metabolism is enhanced in V1aR−/− mice. The cAMP level was enhanced in V1aR−/− mice in response to isoproterenol. The phosphorylation of Akt by insulin stimulation was reduced in V1aR−/− mice. These results suggest that insulin signaling is suppressed in V1aR−/− mice. In addition, the total bile acid, taurine, and cholesterol levels in blood were increased, and an enlargement of the cholecyst was observed in V1aR−/− mice. These results indicated that the production of bile acid was enhanced by the increased level of cholesterol and taurine. Therefore, these results indicated that AVP could modulate the lipid metabolism by the antilipolytic action and the synthesis of bile acid via the V1a receptor.
Delayed development and lifespan extension as features of metabolic lifestyle alteration inC. elegansunder dietary restriction
Authors: Szewczyk Nathaniel J. , Udranszky Ingrid A. , Kozak Elena , Sunga June , Kim Stuart K. , Jacobson Lewis A. , Conley Catharine A.
Published: October 2006

Studies of the model organism Caenorhabditis elegans have almost exclusively utilized growth on a bacterial diet. Such culturing presents a challenge to automation of experimentation and introduces bacterial metabolism as a secondary concern in drug and environmental toxicology studies. Axenic cultivation of C. elegans can avoid these problems, yet past work suggests that axenic growth is unhealthy for C. elegans. Here we employ a chemically defined liquid medium to culture C. elegans and find development slows, fecundity declines, lifespan increases, lipid and protein stores decrease, and gene expression changes relative to that on a bacterial diet. These changes do not appear to be random pathologies associated with malnutrition, as there are no developmental delays associated with starvation, such as L1 or dauer diapause. Additionally, development and reproductive period are fixed percentages of lifespan regardless of diet,suggesting that these alterations are adaptive. We propose that C. elegans can exist as a healthy animal with at least two distinct adult life histories. One life history maximizes the intrinsic rate of population increase, the other maximizes the efficiency of exploitation of the carrying capacity of the environment. Microarray analysis reveals increased transcript levels of daf-16 and downstream targets and past experiments demonstrate that DAF-16 (FOXO) acting on downstream targets can influence all of the phenotypes we see altered in maintenance medium. Thus, life history alteration in response to diet may be modulated by DAF-16. Our observations introduce a powerful system for automation of experimentation on healthy C. elegans and for systematic analysis of the profound impact of diet on animal physiology.
Surgical salvage for stomal recurrence: A multi‐institutional experience
Authors: Gluckman Jack L. , Hamaker Ronald C. , Schuller David E. , Weissler Mark C. , Charles Glenwood A.
Published: October 2006

Recurrence of squamous cell cancer following total laryngectomy constitutes an extremely difficult therapeutic problem. Satisfactory management is elusive and frustrating to the head and neck oncologist. Various recommended therapeutic regimens include symptomatic treatment, palliation with chemotherapy and radiation, and aggressive surgical salvage. While surgery offers the only realistic chance at cure, this procedure is fraught with significant morbidity and a poor success rate.

In an attempt to clarify the role of surgical salvage in these patients, experience with 57 patients with stomal recurrence presenting to three head and neck surgical groups will be presented. Forty‐one of these patients subsequently underwent definitive surgery. The overall 2‐year survival for operated patients was 16% with a 24% determinate survival. Further analysis revealed a 45% 5‐year survival with type 1 and 2 lesions and 9% survival with types 3 and 4. Recommendations regarding indications for surgery are made based on this experience.
Regiospecific Synthesis of 4‐Deoxy‐D‐threo‐hex‐3‐enopyranosides by Simultaneous Activation–Elimination of the Talopyranoside Axial 4‐OH with the NaH/Im2SO2 System: Manifestation of the Stereoelectronic Effect
Authors: Attolino Emanuele , Catelani Giorgio , D’Andrea Felicia
Published: October 2006

A new and high‐yielding method for the regioselective preparation of 4‐deoxy‐ and 2,4‐dideoxy‐2‐acetamido‐β‐D‐threo‐hex‐3‐enopyranosides has been developed. The process involves a simultaneous activation–elimination of the OH‐4 group of β‐D‐talopyranosides and 2‐acetamido‐2‐deoxy‐β‐D‐talopyranosides, mediated by the NaH/N,N′‐sulfuryldiimidazole system at –30 °C. The same reaction applied on the analogous β‐D‐galactopyranosides takes place without any regioselectivity, affording mixtures of hex‐3‐ and hex‐4‐enopyranosides. In the case of the methyl 2,3,6‐tri‐O‐benzyl‐α‐D‐talo‐ and α‐D‐galactopyranosides, the corresponding 4‐O‐imidazylates can be isolated by quenching the reactions at –30 °C. Upon warming these crude products to room temperature, the α‐talo‐4‐O‐imidazylate gives the corresponding hex‐3‐eno derivative in very high yield, but its α‐galacto analogue gives the hex‐4‐enopyranoside enol ether in poor yield. The different regiochemical outcome between the talo and the galacto series has been attributed to the stereoelectronic effect exerted, exclusively in talo‐configured compounds, by the axially disposed C‐2 electronegative substituent, which selectively accelerates the breaking of the antiperiplanar C(3)–H bond. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Laser structuring for back junction silicon solar cells
Authors: Engelhart Peter , Harder Nils‐Peter , Grischke Rainer , Merkle Agnes , Meyer Rüdiger , Brendel Rolf
Published: October 2006

We demonstrate mask‐free fabrication of a 22·0%‐efficient crystalline Si solar cell by applying laser ablation of Si and by laser ablation of protective coatings. The bulk absorber material is a p‐type float zone silicon wafer and the designated cell area is 4 cm2. While the processing time of our laboratory‐type of laser system is far too slow for industrial processing, we estimate on the basis of our experiments that laser processing of 12·5 × 12·5 cm2‐sized solar cells in just a few seconds is feasible with commercially available equipment. Copyright © 2006 John Wiley & Sons, Ltd.
Surface enhanced Raman spectroscopy of flat and curved carbon cluster
Authors: Hölzl C. , Kuzmany H. , Hulman M. , Wu J. , Müllen K. , Boroviak‐Palen E. , Kalenczuk R. J. , Kukovecz A.
Published: October 2006

Hexa‐peri hexabenzocarbonate (HBC) are small cluster of a graphene plane with various side groups for stabilization. Due to theire ate geometry they are ideal candidates to study surface enhanced Raman spectroscopy (SERS). Very thin films HBC were vaopur deposited to different SERS‐active Ag‐surfaces. The enhancement of the Raman signal was studied with the goal to develop an Ag‐surface of optimum enhancement, for multiple use and very simple sample preparation. For the current surface the observed enhancement is up to 106. For SWNT filled with Ag‐particles the SERS effect could also be shown – but enhancement was only a factor 10. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time‐step adaptivity in variational integrators with application to contact problems
Authors: Modin K. , Führer C.
Published: October 2006

Variable time‐step methods, with general step‐size control objectives, are developed within the framework of variational integrators. This is accomplished by introducing discrete transformations similar to Poincarés time transformation. While gaining from adaptive time‐steps, the resulting integrators preserve the structural advantages of variational integrators, i.e. they are symplectic and momentum preserving. As an application, the methods are utilized for dynamic multibody systems governed by contact force laws. A suitable scaling function defining the step‐size control objective is derived.
From the Personal to the Public – Cadbury-Brown's Public Sector work
Authors: Harwood Elain
Published: October 2006

H. T. Cadbury-Brown's architecture in the public sector in Britain is placed in the context of his background and the work of his contemporaries.