bluuebunny/crossref_metadata_2025 huggingface dataset:
A
cdc5
+
homolog of a higher plant,
Arabidopsis thaliana
Authors: Hirayama Takashi , Shinozaki Kazuo
Published: July 2002

We cloned and characterized a cDNA corresponding to a
cdc5
+
homolog of the higher plant,
Arabidopsis thaliana
. The cDNA, named
AtCDC5
cDNA, encodes a polypeptide of 844 amino acid
residues. The amino acid sequence of N-terminal one-fourth region of
the predicted protein bears significant similarity to that of
Schizosaccharomyces pombe
Cdc5 and Myb-related proteins.
Overexpression of the
AtCDC5
cDNA in
S.
pombe
cells is able to complement the growth defective
phenotype of a
cdc5
temperature-sensitive mutant. These
results indicate that the
AtCDC5
gene is a plant
counterpart of
S. pombe cdc5
+
. This is the
first report of a
cdc5
+
-like gene in a
multicellular organism. We also demonstrated that a recombinant AtCDC5
protein possesses a sequence specific DNA binding activity (CTCAGCG)
and the AtCDC5 gene is expressed extensively in shoot and root
meristems. In addition, we cloned a PCR fragment corresponding to the
DNA binding domain of human Cdc5-like protein. These results strongly
suggest that Cdc5-like protein exists in all eukaryotes and may
function in cell cycle regulation.
Progression of human breast cancers to the metastatic state is linked to hydroxyl radical-induced DNA damage.
Authors: Malins D C , Polissar N L , Gunselman S J
Published: July 2002

Hydroxyl radical damage in metastatic tumor DNA was elucidated in women with breast cancer, and a comparison was made with nonmetastatic tumor DNA. The damage was identified by using statistical models of modified base and Fourier transform-infrared spectral data. The modified base models revealed a greater than 2-fold increase in hydroxyl radical damage in the metastatic tumor DNA compared with the nonmetastatic tumor DNA. The metastatic tumor DNA also exhibited substantially greater base diversity than the nonmetastatic DNA, and a progression of radical-induced base damage was found to be associated with the growth of metastatic tumors. A three-dimensional plot of principal components from factor analysis, derived from infrared spectral data, also showed that the metastatic tumor DNA was substantially more diverse than the tightly grouped nonmetastatic tumor DNA. These cohesive, independently derived findings suggest that the hydroxyl radical generates DNA phenotypes with various metastatic potentials that likely contribute to the diverse physiological properties and heterogeneity characteristic of metastatic cell populations.
Active control of waves in a cochlear model with subpartitions.
Authors: Chadwick R S , Dimitriadis E K , Iwasa K H
Published: July 2002

Multiscale asymptotic methods developed previously to study macromechanical wave propagation in cochlear models are generalized here to include active control of a cochlear partition having three subpartitions, the basilar membrane, the reticular lamina, and the tectorial membrane. Activation of outer hair cells by stereocilia displacement and/or by lateral wall stretching result in a frequency-dependent force acting between the reticular lamina and basilar membrane. Wavelength-dependent fluid loads are estimated by using the unsteady Stokes' equations, except in the narrow gap between the tectorial membrane and reticular lamina, where lubrication theory is appropriate. The local wavenumber and subpartition amplitude ratios are determined from the zeroth order equations of motion. A solvability relation for the first order equations of motion determines the subpartition amplitudes. The main findings are as follows: The reticular lamina and tectorial membrane move in unison with essentially no squeezing of the gap; an active force level consistent with measurements on isolated outer hair cells can provide a 35-dB amplification and sharpening of subpartition waveforms by delaying dissipation and allowing a greater structural resonance to occur before the wave is cut off; however, previously postulated activity mechanisms for single partition models cannot achieve sharp enough tuning in subpartitioned models.
Unforeseen Americas: the making of New World societies in anthropological perspective.
Authors: Wolf E R
Published: July 2002

The European discovery and settlement of the Americas revealed unforeseen dimensions and gave rise to unpremeditated ways of coping with the resulting problems. This paper traces out the enduring social and cultural implications of this foundational encounter.
Relative effects of female fecundity and male mating success on fertility selection in Drosophila pseudoobscura.
Authors: Brockett M M , Alavi H , Anderson W W
Published: July 2002

The fertility component of natural selection acting on chromosomal inversions in two experimental populations of Drosophila pseudoobscura was subdivided into the effects of female fecundity and male mating success. The offspring of the three female genotypes could be distinguished by their mitochondrial DNA haplotypes, thus permitting a direct measurement of the relative fecundities of the female genotype. The effects of male mating success on inversion frequency were measured by comparing inversion frequencies in parents and their offspring. Selection by fertility caused significant changes in inversion frequency in both populations. In one population, the changes in inversion frequency due to female fecundity and to male mating success were comparable. In the other population, however, the changes in inversion frequency due to male mating success were considerably larger than those due to female fecundity. The difference between the two populations underscores the intrinsic variability of the fertility component of fitness.
Mutation detection with MutH, MutL, and MutS mismatch repair proteins.
Authors: Smith J , Modrich P
Published: July 2002

Escherichia coli methyl-directed mismatch repair is initiated by MutS-, MutL-, and ATP-dependent activation of MutH endonuclease, which cleaves at d(GATC) sites in the vicinity of a mismatch. This reaction provides an efficient method for detection of mismatches in heteroduplexes produced by hybridization of genetically distinct sequences after PCR amplification. Multiple examples of transition and transversion mutations, as well as one, two, and three nucleotide insertion/deletion mutants, have been detected in PCR heteroduplexes ranging in size from 400 bp to 2.5 kb. Background cleavage of homoduplexes is largely due to polymerase errors that occur during amplification, and the MutHLS reaction provides an estimate of the incidence of mutant sequences that arise during PCR.
The major yeast poly(A)-binding protein is associated with cleavage factor IA and functions in premessenger RNA 3′-end formation
Authors: Minvielle-Sebastia Lionel , Preker Pascal J. , Wiederkehr Thomas , Strahm Yvan , Keller Walter
Published: July 2002

Polyadenylation of premessenger RNAs occurs posttranscriptionally in the nucleus of eukaryotic cells by cleavage of the precursor and polymerization of adenosine residues. In the yeast
Saccharomyces cerevisiae
, the mature poly(A) tail ranges from 60 to 70 nucleotides. 3′-end processing can be reproduced
in vitro
with purified factors. The cleavage reaction requires cleavage factors I and II (CF I and CF II), whereas polyadenylation involves CF I, polyadenylation factor I (PFI), and poly(A) polymerase (Pap1p). CF I has recently been separated into two factors, CF IA and CF IB. We have independently purified CF IA and found that five polypeptides cofractionate with the activity. They include Rna14p, Rna15p, Pcf11p, a new protein called Clp1p, and remarkably, the major poly(A)-binding protein Pab1p. Extracts from strains where the
PAB1
gene is mutated or deleted are active for cleavage but generate transcripts bearing abnormally long poly(A) tracts. Complementation with recombinant Pab1p not only restores the length of the poly(A) tails to normal, but also triggers a poly(A) shortening activity. In addition, a monoclonal Pab1p antibody prevents the formation of poly(A) tails in extracts or in a reconstituted system. Our data support the notion that Pab1p is involved in the length control of the poly(A) tails of yeast mRNAs and define a new essential function for Pab1p in the formation of mature mRNAs.
Relax promotes ectopic neuronal differentiation in
Xenopus
embryos
Authors: Ravassard Philippe , Vallin Jérome , Mallet Jacques , Icard-Liepkalns Christine
Published: July 2002

We previously isolated a novel rat cDNA encoding a basic helix–loop–helix transcription factor named Relax, whose expression in the developing central nervous system is strictly limited to discrete domains containing precursor cells. The timing of Relax expression coincides with neuronal differentiation. To investigate the involvement of Relax in neurogenesis we tested whether Relax activated neural genes in the ectoderm by injecting Relax RNA into
Xenopus
embryos. We demonstrate that ectopic Relax expression induces a persistent enlargement of the neural plate and converts presumptive epidermal cells into neurons. This indicates that Relax, when overexpressed in
Xenopus
embryos, has a neuronal fate-determination function. Analyses both of Relax overexpression in the frog and of the distribution of Relax in the rat neural tube strongly suggest that Relax is a neuronal fate-determination gene.
Orderly cortical representation of vowels based on formant interaction
Authors: Ohl Frank W. , Scheich Henning
Published: July 2002

Psychophysical experiments have shown that the discrimination of human vowels chiefly relies on the frequency relationship of the first two peaks F1 and F2 of the vowel’s spectral envelope. It has not been possible, however, to relate the two-dimensional (F1,F2)-relationship to the known organization of frequency representation in auditory cortex. We demonstrate that certain spectral integration properties of neurons are topographically organized in primary auditory cortex in such a way that a transformed (F1,F2) relationship sufficient for vowel discrimination is realized.
Zeta functions and Eisenstein series on classical groups
Authors: Shimura Goro
Published: July 2002

We construct an Euler product from the Hecke eigenvalues of an
automorphic form on a classical group and prove its analytic
continuation to the whole complex plane when the group is a unitary
group over a CM field and the eigenform is holomorphic. We also prove
analytic continuation of an Eisenstein series on another unitary group,
containing the group just mentioned defined with such an eigenform. As
an application of our methods, we prove an explicit class number
formula for a totally definite hermitian form over a CM field.
Expression of a dominant-negative type II transforming growth factor β (TGF-β) receptor in the epidermis of transgenic mice blocks TGF-β-mediated growth inhibition
Authors: Wang Xiao-Jing , Greenhalgh David A. , Bickenbach Jackie R. , Jiang Aibo , Bundman Donnie S. , Krieg Thomas , Derynck Rik , Roop Dennis R.
Published: July 2002

To determine whether a functional type II receptor of transforming growth factor β (TGF-β) is required to mediate the growth inhibitory effect of TGF-β on the skin
in vivo
, we have generated transgenic mice that overexpress a dominant negative-type II TGF-β receptor (ΔβRII) in the epidermis. The ΔβRII mice exhibited a thickened and wrinkled skin, and histologically the epidermis was markedly hyperplastic and hyperkeratotic.
In vivo
labeling with BrdUrd showed a 2.5-fold increase in the labeling index over controls, with labeled nuclei occurring in both basal and suprabasal cells of transgenic epidermis. In heterozygotes, this skin phenotype gradually diminished, and by 10–14 days after birth the transgenic mice were indistinguishable from their normal siblings. However, when F
1
mice were mated to homozygosity, perinatal lethality occurred due to the severe hyperkeratotic phenotype, which restricted movement. Cultured primary keratinocytes from ΔβRII mice also exhibited an increased rate of growth in comparison with nontransgenic controls, and were resistant to TGF-β-induced growth inhibition. These data document the role of the type II TGF-β receptor in mediating TGF-β-induced growth inhibition of the epidermis
in vivo
and in maintenance of epidermal homeostasis.
Cosmic microwave background theory
Authors: Bond J. Richard
Published: July 2002

A long-standing goal of theorists has been to constrain
cosmological parameters that define the structure formation theory from
cosmic microwave background (CMB) anisotropy experiments and
large-scale structure (LSS) observations. The status and future promise
of this enterprise is described. Current band-powers in ℓ-space are
consistent with a Δ
T
flat in frequency and broadly follow
inflation-based expectations. That the levels are
∼(10
−5
)
2
provides strong support for the
gravitational instability theory, while the Far Infrared Absolute
Spectrophotometer (FIRAS) constraints on energy injection rule out
cosmic explosions as a dominant source of LSS. Band-powers at ℓ ≳
100 suggest that the universe could not have re-ionized too early. To
get the LSS of Cosmic Background Explorer (COBE)-normalized
fluctuations right provides encouraging support that the initial
fluctuation spectrum was not far off the scale invariant form that
inflation models prefer: e.g., for tilted Λ cold dark matter
sequences of fixed 13-Gyr age (with the Hubble constant
H
0
marginalized),
n
s
=
1.17 ± 0.3 for Differential Microwave Radiometer (DMR) only;
1.15 ± 0.08 for DMR plus the SK95 experiment; 1.00 ± 0.04
for DMR plus all smaller angle experiments; 1.00 ± 0.05 when LSS
constraints are included as well. The CMB alone currently gives weak
constraints on Λ and moderate constraints on Ω
tot
, but
theoretical forecasts of future long duration balloon and satellite
experiments are shown which predict percent-level accuracy among a
large fraction of the 10+ parameters characterizing the cosmic
structure formation theory, at least if it is an inflation variant.
Screening for overlapping bacterial artificial chromosome clones by PCR analysis with an arbitrary primer
Authors: Xu Jichen , Yang Daichang , Domingo Jessica , Ni Junjian , Huang Ning
Published: July 2002

In this article, we used PCR analysis with arbitrary primers (AP-PCR) to screen for overlapping bacterial artificial chromosome (BAC) clones and assembly of contigs. A rice BAC library with three genome equivalents was used to prepare pooled BAC DNA. Twenty-two arbitrary primers were used to survey the pooled BAC DNAs and individual BAC DNAs. Each primer identified 1–10 loci, and the average was 4.4 loci. There were 1–5 overlapping clones in each locus, and the average was 2.5 clones. A total of 245 BAC clones were identified as overlapping by AP-PCR and the identities were confirmed by DNA–DNA hybridization. The 245 BAC clones were then assembled into 80 contigs and 17 single-clone loci. The results indicated that PCR analysis with arbitrary primers is a powerful tool in screening for overlapping BAC clones with high accuracy and efficiency. The use of AP-PCR analysis should speed up the construction of physical maps of the plant and animal genomes, as well as the rice genome.
Translation inhibitors stabilize
Escherichia coli
mRNAs independently of ribosome protection
Authors: Lopez P. J. , Marchand I. , Yarchuk O. , Dreyfus M.
Published: July 2002

Translation inhibitors such as chloramphenicol in prokaryotes or cycloheximide in eukaryotes stabilize many or most cellular mRNAs. In
Escherichia coli
, this stabilization is ascribed generally to the shielding of mRNAs by stalled ribosomes. To evaluate this interpretation, we examine here how inhibitors affect the stabilities of two untranslated RNAs, i.e., an engineered
lacZ
mRNA lacking a ribosome binding site, and a small regulatory RNA, RNAI. Whether they block elongation or initiation, all translation inhibitors tested stabilized these RNAs, indicating that stabilization does not necessarily reflect changes in packing or activity of translating ribosomes. Moreover, both the initial RNase E-dependent cleavage of RNAI and
lacZ
mRNA and the subsequent attack of RNAI by polynucleotide phosphorylase and poly(A)-polymerase were slowed. Among various possible mechanisms for this stabilization, we discuss in particular a passive model. When translation is blocked, rRNA synthesis is known to increase severalfold and rRNA becomes unstable. Meanwhile, the pools of RNase E and polynucleotide phosphorylase, which, in growing cells, are limited because these RNases autoregulate their own synthesis, cannot expand. The processing/degradation of newly synthesized rRNA would then titrate these RNases, causing bulk mRNA stabilization.
ErbB2 expression increases the spectrum and potency of ligand-mediated signal transduction through ErbB4
Authors: Wang Ling-Mei , Kuo Angera , Alimandi Maurizio , Veri Maria C. , Lee Chong-Chou , Kapoor Veena , Ellmore Nelson , Chen Xiao-Hong , Pierce Jacalyn H.
Published: July 2002

Interleukin 3-dependent murine 32D cells do not detectably express members of the ErbB receptor family and do not proliferate in response to known ligands for these receptors. 32D transfectants were generated expressing human ErbB4 alone (32D.E4) or with ErbB2 (32D.E2/E4). Epidermal growth factor (EGF), neuregulin 1-β (NRG1-β), betacellulin (BTC), transforming growth factor-α (TGF-α), heparin binding-EGF (HB-EGF), and amphiregulin were analyzed for their ability to mediate mitogenesis in these transfectants. 32D.E4 responded mitogenically to NRG1-β and BTC. Surprisingly, EGF also induced significant DNA synthesis and TGF-α was negligibly mitogenic on 32D.E4 cells, whereas HB-EGF and amphiregulin were inactive. Although coexpression of ErbB2 with ErbB4 in 32D.E2/E4 cells did not significantly alter DNA synthesis in response to NRG1-β or BTC, it greatly enhanced mitogenesis elicited by EGF and TGF-α and unmasked the ability of HB-EGF to induce proliferation. EGF-related ligands that exhibited potent mitogenic activity on 32D.E2/E4 cells at low concentrations induced adherence, morphological alterations, and up-regulation of the Mac-1 integrin and FcγRII/III at higher concentrations. While
125
I-EGF could be specifically crosslinked to both 32D.E4 and 32D.E2/E4 cells, its crosslinking capacity was greatly enhanced in the cotransfected cells. The ability of the various ligands to mediate proliferation and/or adhesion in the two transfectants correlated with their capacity to induce substrate tyrosine phosphorylation and to initiate and sustain activation of mitogen-activated protein kinase. We conclude that the ability of ErbB4 to mediate signal transduction through EGF-like ligands is broader than previously assumed and can be profoundly altered by the concomitant expression of ErbB2.
Cloning of
Leishmania
nucleoside transporter genes by rescue of a transport-deficient mutant
Authors: Vasudevan Gayatri , Carter Nicola S. , Drew Mark E. , Beverley Stephen M. , Sanchez Marco A. , Seyfang Andreas , Ullman Buddy , Landfear Scott M.
Published: July 2002

All parasitic protozoa studied to date are incapable of purine biosynthesis and must therefore salvage purine nucleobases or nucleosides from their hosts. This salvage process is initiated by purine transporters on the parasite cell surface. We have used a mutant line (TUBA5) of
Leishmania donovani
that is deficient in adenosine/pyrimidine nucleoside transport activity (LdNT1) to clone genes encoding these nucleoside transporters by functional rescue. Two such genes,
LdNT1
.
1
and
LdNT1.2
, have been sequenced and shown to encode deduced polypeptides with significant sequence identity to the human facilitative nucleoside transporter hENT1. Hydrophobicity analysis of the LdNT1.1 and LdNT1.2 proteins predicted 11 transmembrane domains. Transfection of the adenosine/pyrimidine nucleoside transport-deficient TUBA5 parasites with vectors containing the
LdNT1.1
and
LdNT1.2
genes confers sensitivity to the cytotoxic adenosine analog tubercidin and concurrently restores the ability of this mutant line to take up [
3
H]adenosine and [
3
H]uridine. Moreover, expression of the
LdNT1
.2 ORF in
Xenopus
oocytes significantly increases their ability to take up [
3
H]adenosine, confirming that this single protein is sufficient to mediate nucleoside transport. These results establish genetically and biochemically that both
LdNT1
genes encode functional adenosine/pyrimidine nucleoside transporters.
Intercellular signaling in
Stigmatella aurantiaca
: Purification and characterization of stigmolone, a myxobacterial pheromone
Authors: Plaga Wulf , Stamm Irmela , Schairer Hans Ulrich
Published: July 2002

The myxobacterium
Stigmatella aurantiaca
passes through a life cycle that involves formation of a multicellular fruiting body as the most complex stage. An early step in this differentiation process depends on a signal factor secreted by the cells when nutrients become limited. The formation of a fruiting body from a small cell population can be accelerated by addition of this secreted material. The bioactive compound was found to be steam volatile. It was purified to homogeneity by steam distillation followed by reversed-phase and normal-phase HPLC. The pheromone was named stigmolone, in accordance with the structure 2,5,8-trimethyl-8-hydroxy-nonan-4-one, as determined by NMR and mass spectrometry. Stigmolone represents a structurally unique and highly bioactive prokaryotic pheromone that is effective in the bioassay at 1 nM concentration.
Mutational analysis of protein phosphatase 2C involved in abscisic acid signal transduction in higher plants
Authors: Sheen Jen
Published: July 2002

Protein phosphatase 2C (PP2C) is a class of ubiquitous and evolutionarily conserved serine/threonine PP involved in stress responses in yeasts, mammals, and plants. Here, I present mutational analysis of two
Arabidopsis thaliana
PP2Cs, encoded by
ABI1
and
AtPP2C
, involved in the plant stress hormone abscisic acid (ABA) signaling in maize mesophyll protoplasts. Consistent with the crystal structure of the human PP2C, the mutation of two conserved motifs in ABI1, predicted to be involved in metal binding and catalysis, abolished PP2C activity. Surprisingly, although the DGH177–179KLN mutant lost the ability to be a negative regulator in ABA signaling, the MED141–143IGH mutant still inhibited ABA-inducible transcription, perhaps through a dominant interfering effect. Moreover, two G to D mutations near the DGH motif eliminated PP2C activity but displayed opposite effects on ABA signaling. The G174D mutant had no effect but the G180D mutant showed strong inhibitory effect on ABA-inducible transcription. Based on the results that a constitutive PP2C blocks but constitutive Ca
2+
-dependent protein kinases (CDPKs) activate ABA responses, the MED141–143IGH and G180D dominant mutants are unlikely to impede the wild-type PP2C and cause hyperphosphorylation of substrates. In contrast, these dominant mutants could trap cellular targets and prevent phosphorylation by PKs required for ABA signaling. The equivalent mutations in AtPP2C showed similar effects on ABA responses. This study suggests a mechanism for the action of dominant PP2C mutants that could serve as valuable tools to understand protein–protein interactions mediating ABA signal transduction in higher plants.
Activity patterns of neurosecretory cells releasing pheromonotropic neuropeptides in the moth
Bombyx mori
Authors: Ichikawa Toshio
Published: July 2002

Short- and long-term firing patterns of neurosecretory cells releasing pheromonotropic neuropeptides in the silkworm moth
Bombyx mori
were examined. The cells showed three types of rhythmic changes in firing activity. Bursting activities with an interval of several seconds were synchronized with rhythmic abdominal motions for calling behavior. A slow fluctuation in firing activity over a period of several minutes depended on cyclic alternations of the flow of hemolymph. The electrical activity displayed a diel rhythm that related to light/dark cycles of the environment and sex pheromone titers in the pheromone gland. In addition to a transient inhibition of firing caused by a tactile or light stimulus, a long-term permanent inhibition was induced by mating with a fertile male. Thus, the insect neurosecretory system is highly coordinated with physiology and behavior in
Bombyx mori
and is influenced by external stimuli.
Design, total chemical synthesis, and binding properties of a [Leu-91-
N
1
-methyl-7-azaTrp]Ras-binding domain of c-Raf-1
Authors: Sydor Jens R. , Herrmann Christian , Kent Stephen B. H. , Goody Roger S. , Engelhard Martin
Published: July 2002

The Ras-binding domain (RBD) of c-Raf-1 has been synthesized chemically, taking advantage of the chemical ligation of two peptide fragments of the protein. This procedure allowed incorporation of an unnatural amino acid (
N
1
-methyl-7-azatryptophan) at position 91 of RBD, producing a protein with fluorescent properties distinct from and distinguishable from those of proteins containing the natural fluorophore tryptophan. The resulting protein was shown to interact with Ras in a manner that was almost indistinguishable from that of unmodified RBD based on transient kinetic monitoring of the binding event. Modified RBD containing the
l
-isomer of the unnatural amino acid or its racemic
d
,
l
mixture appeared to interact identically with Ras. The approach demonstrates a general procedure for the introduction of unnatural amino acids that can be used for monitoring protein–protein interactions and for the introduction of an unnatural backbone structure at strategic positions.
Chimerism in humans after intragenic recombination at the haptoglobin locus during early embryogenesis
Authors: Asakawa Jun-ichi , Kodaira Mieko , Nakamura Nori , Satoh Chiyoko , Fujita Mikio
Published: July 2002

The human haptoglobin (HP)
HP*2
allele contains a 1.7-kilobase (kb) intragenic duplication that arose after a unique nonhomologous recombination between the prototype
HP*1
alleles. During a genetic screening of 13,000 children of survivors exposed to atomic-bomb radiation and 10,000 children of unexposed persons, two children suspected of carrying
de novo
mutations at the haptoglobin locus were identified (one in each group). DNA analyses of single-cell-derived colonies of Epstein–Barr virus-transformed B cells revealed that the two children were mosaics comprising
HP*2/HP*2
and
HP*2/HP*1
cells at a ratio of ≈3:1. We infer that the latter cells are caused by reversion of one
HP*2
allele to
HP*1
through an intramolecular homologous recombination between the duplicated segments of the
Hp*2
allele that excised one of the segments. Because the mosaicism is substantial (≈25%), this recombination must have occurred in early embryogenesis. The frequency of finding these children and the extent of their mosaicisms corresponds to an
HP*2
to
HP*1
reversion rate of 8 × 10
−6
per cell during development. This leads to the prediction that the
HP*1
allele also will be represented, although usually at a very low frequency, in any HP2-2 person. We tested this prediction by using PCR for a single individual and found the
HP*1
allele at frequencies of 4 × 10
−6
and 3 × 10
−6
in somatic and sperm cells. The
HP*1
allele was detected by PCR in all four other HP2–2 individuals, which supports the regular but rare occurrence somatically of homologous recombination within duplicated regions in humans, in agreement with previous observations in mouse and
Drosophila
.
Global climate change
Authors: Alley Richard B. , Lynch-Stieglitz Jean , Severinghaus Jeffrey P.
Published: July 2002

Most of the last 100,000 years or longer has been characterized by
large, abrupt, regional-to-global climate changes. Agriculture and
industry have developed during anomalously stable climatic conditions.
New, high-resolution analyses of sediment cores using multiproxy and
physically based transfer functions allow increasingly confident
interpretation of these past changes as having been caused by “band
jumps” between modes of operation of the climate system. Recurrence
of such band jumps is possible and might be affected by human
activities.
Ku is associated with the telomere in mammals
Authors: Hsu Hsin-Ling , Gilley David , Blackburn Elizabeth H. , Chen David J.
Published: July 2002

Telomeres are specialized DNA/protein complexes that comprise the ends of eukaryotic chromosomes. The highly expressed Ku heterodimer, composed of 70 and 80
K
d
subunits (Ku70 and Ku80), is the high-affinity DNA binding component of the DNA-dependent protein kinase. Ku is critical for nonhomologous DNA double-stranded break repair and site-specific recombination of V(D)J gene segments. Ku also plays an important role in telomere maintenance in yeast. Herein, we report, using an
in vivo
crosslinking method, that human and hamster telomeric DNAs specifically coimmunoprecipitate with human Ku80 after crosslinking. Localization of Ku to the telomere does not depend on the DNA-dependent protein kinase catalytic component. These findings suggest a direct link between Ku and the telomere in mammalian cells.
Repeated, but not acute, stress suppresses inflammatory plasma extravasation
Authors: Strausbaugh Holly J. , Dallman Mary F. , Levine Jon D.
Published: July 2002

Clinical findings suggest that inflammatory disease symptoms are aggravated by ongoing, repeated stress, but not by acute stress. We hypothesized that, compared with single acute stressors, chronic repeated stress may engage different physiological mechanisms that exert qualitatively different effects on the inflammatory response. Because inhibition of plasma extravasation, a critical component of the inflammatory response, has been associated with increased disease severity in experimental arthritis, we tested for a potential repeated stress-induced inhibition of plasma extravasation. Repeated, but not single, exposures to restraint stress produced a profound inhibition of bradykinin-induced synovial plasma extravasation in the rat. Experiments examining the mechanism of inhibition showed that the effect of repeated stress was blocked by adrenalectomy, but not by adrenal medullae denervation, suggesting that the adrenal cortex mediates this effect. Consistent with known effects of stress and with mediation by the adrenal cortex, restraint stress evoked repeated transient elevations of plasma corticosterone levels. This elevated corticosterone was necessary and sufficient to produce inhibition of plasma extravasation because the stress-induced inhibition was blocked by preventing corticosterone synthesis and, conversely, induction of repeated transient elevations in plasma corticosterone levels mimicked the effects of repeated stress. These data suggest that repetition of a mild stressor can induce changes in the physiological state of the animal that enable a previously innocuous stressor to inhibit the inflammatory response. These findings provide a potential explanation for the clinical association between repeated stress and aggravation of inflammatory disease symptoms and provide a model for study of the biological mechanisms underlying the stress-induced aggravation of chronic inflammatory diseases.
Principles of quasi-equivalence and Euclidean geometry govern the assembly of cubic and dodecahedral cores of pyruvate dehydrogenase complexes
Authors: Izard Tina , Ævarsson Arnthor , Allen Mark D. , Westphal Adrie H. , Perham Richard N. , de Kok Aart , Hol Wim G. J.
Published: July 2002

The pyruvate dehydrogenase multienzyme complex
(
M
r
of 5–10 million) is assembled around a
structural core formed of multiple copies of dihydrolipoyl
acetyltransferase (E2p), which exhibits the shape of either a cube or a
dodecahedron, depending on the source. The crystal structures of the
60-meric dihydrolipoyl acyltransferase cores of
Bacillus
stearothermophilus
and
Enterococcus faecalis
pyruvate
dehydrogenase complexes were determined and revealed a remarkably
hollow dodecahedron with an outer diameter of ≈237 Å, 12 large
openings of ≈52 Å diameter across the fivefold axes, and an inner
cavity with a diameter of ≈118 Å. Comparison of cubic and
dodecahedral E2p assemblies shows that combining the principles of
quasi-equivalence formulated by Caspar and Klug [Caspar, D. L. & Klug,
A. (1962)
Cold Spring Harbor Symp. Quant. Biol.
27, 1–4]
with strict Euclidean geometric considerations results in predictions
of the major features of the E2p dodecahedron matching the observed
features almost exactly.
Cocaine vaccines: Antibody protection against relapse in a rat model
Authors: Carrera M. Rocío A. , Ashley Jon A. , Zhou Bin , Wirsching Peter , Koob George F. , Janda Kim D.
Published: July 2002

The efficacy of active immunization with the cocaine immunogen GNC-keyhole limpet hemocyanin (KLH) in preventing cocaine self-administration reinstatement was assessed in rats. An animal model of relapse was used where rats were trained to self-administer cocaine, subjected to a period of extinction by substituting the drug for saline, vaccinated, and re-exposed to cocaine. Compared with controls, animals immunized with GNC-KLH did not reinstate cocaine self-administration behavior when given a noncontingent cocaine infusion on two consecutive days. Upon double and triple infusions, 38–62% of vaccinated animals failed to reinstate as compared with full reinstatement in all control animals. Exposure to ad libitum cocaine reinstated baseline values in control animals and resulted in double to triple the baseline values of self-infusions in vaccinated animals, suggesting a partial antibody-mediated blockade of cocaine access to the central nervous system. This compensating effect was blocked by passive immunization pretreatment with the monoclonal IgG GNC92H2 in both vaccinated and control groups. To further assess the surmountability potential of GNC-KLH-induced antibody titers by cocaine self-administration, and the capacity of these titers to block the reinforcing effects of the drug, rats were tested at various doses of cocaine (0.015–0.5 mg/infusion). Active immunization with GNC-KLH produced approximately an 8-fold rightward shift of the dose-effect function for cocaine. The results reported suggest that immunopharmacotherapy may offer a promising means to treat cocaine abuse by aiding in the prevention of relapse.
Rapid generation of nested chromosomal deletions on mouse chromosome 2
Authors: LePage David F. , Church Deanna M. , Millie Elise , Hassold Terry J. , Conlon Ronald A.
Published: July 2002

Nested chromosomal deletions are powerful genetic tools. They are particularly suited for identifying essential genes in development either directly or by screening induced mutations against a deletion. To apply this approach to the functional analysis of mouse chromosome 2, a strategy for the rapid generation of nested deletions with Cre recombinase was developed and tested. A
loxP
site was targeted to the
Notch1
gene on chromosome 2. A targeted line was cotransfected with a second
loxP
site and a plasmid for transient expression of Cre. Independent random integrations of the second
loxP
site onto the targeted chromosome in direct repeat orientation created multiple nested deletions. By virtue of targeting in an F
1
hybrid embryonic stem cell line, F
1
(129S1×Cast/Ei), the deletions could be verified and rapidly mapped. Ten deletions fell into seven size classes, with the largest extending six or seven centiMorgans. The cytology of the deletion chromosomes were determined by fluorescent
in situ
hybridization. Eight deletions were cytologically normal, but the two largest deletions had additional rearrangements. Three deletions, including the largest unrearranged deletion, have been transmitted through the germ line. Several endpoints also have been cloned by plasmid rescue. These experiments illustrate the means to rapidly create and map deletions anywhere in the mouse genome. They also demonstrate an improved method for generating nested deletions in embryonic stem cells.
Very intense pulse in the groundwater flow in fissurized-porous stratum
Authors: Barenblatt G. I. , Ingerman E. A. , Shvets H. , Vázquez J. L.
Published: July 2002

An asymptotic solution is obtained corresponding to a very intense pulse: a sudden strong increase and fast subsequent decrease of the water level at the boundary of semi-infinite fissurized-porous stratum. This flow is of practical interest: it gives a model of a groundwater flow after a high water period or after a failure of a dam around a collector of liquid waste. It is demonstrated that the fissures have a dramatic influence on the groundwater flow, increasing the penetration depth and speed of fluid penetration into the stratum. A characteristic property of the flow in fissurized-porous stratum is the rapid breakthrough of the fluid at the first stage deeply into the stratum via a system of cracks, feeding of porous blocks by the fluid in cracks, and at a later stage feeding of advancing fluid flow in fissures by the fluid, accumulated in porous blocks.
Aspiration, Preaspiration, Deaspiration, Sonorant Devoicing and Spirantization in Icelandic
Authors: Ringen Catherine O.
Published: July 2002

This paper presents a novel analysis of aspiration, preaspiration, and the related phenomena of sonorant devoicing and spirantization in an Optimality Theoretic framework. Central to the analysis are two constraints: one requires that the feature [spread glottis] be shared by adjacent consonants, and another prohibits moraic [spread glottis] stops. Aspirated stops are singleton stops that are specified as [spread glottis]. Unaspirated stops either have no [spread glottis] feature or share a [spread glottis] feature with another consonant. There is no movement of aspiration or the [spread glottis] feature from one segment to another as in earlier analyses. This account is fully in accord with phonetic descriptions and is of theoretical interest because it supports the fission analysis of preaspiration and is consistent with the assumption that geminates are moraic consonants.
Technology and Globalisation: An Overview
Authors: Mcmahon Peter
Published: July 2002

Globalisation is a term too easily used without reference to the basic enabling role of technology. It is the interplay between available technology and the prevailing social processes, especially dominant institutional forms, which has essentially determined the long process of globalisation. This process has gone through phases exhibiting varying core characteristics as production, transport and communications technologies especially have interrelated with the institutional structures of nation states, military forces and firms especially. However, a general trend to geographical and tendentially global expansion has been constant, along with an intensification of information processing and communications capacity. The role of technology has been to enable this physical expansion culminating in globalisation, including the techno-industrial capacity that increasingly drove it through the construction of better and cheaper artefacts.
The association between naltrexone compliance and daily supervision
Authors: HULSE G. K. , BASSO M R.
Published: July 2002

Most studies investigating the efficacy of naltrexone maintenance as a treatment for illicit heroin use have reported poor patient compliance in taking naltrexone. A number of studies have, however, reported better compliance when patients receive family therapy, or when patients resided in a supportive family environment. These studies suggest that patient outcomes on naltrexone maintenance may be better if there is ongoing family support to continue naltrexone use. The current study investigated 6‐month outcome status in 300 illicit heroin users who commenced naltrexone maintenance in a community‐based out‐patient treatment programme. The study aimed to assess the relationship between vigilance of naltrexone supervision by salient others over the first 6 weeks of treatment and patient status at 6 months. Supervision of naltrexone at week 6 was a predictor of a patient's status at 6 months, with those receiving less supervision of 3–4 days more likely to have returned to heroin use or be assessed as ‘heroin use undetermined’. In contrast, patients who still received naltrexone supervision for 6 or 7 days per week at week 6 were more likely to be taking naltrexone or were naltrexone‐ and heroin‐free at 6 months. It is argued that since relapse to heroin use is a common occurrence, vigilant supervision of naltrexone dosing in a supportive environment may improve patient retention and reduce relapse. It is suggested that poor outcomes reported in many previous studies may reflect use of inadequate supportive frameworks that encourage naltrexone compliance.
Cytokine profiles in early rejection following OKT3 treatment in liver transplant patients
Authors: Roayaie Sasan , Sheiner Patricia A. , Emre Sukru , Guy Steven , Schwartz Myron E. , Boros Peter , Miller Charles M.
Published: July 2002

OKT3, a murine monoclonal antibody specific to the human CD3 complex, induces immunosuppression by depletion of T cells. Administration of OKT3 results in significant release of proinflammatory cytokines, such as TNFα and IL1β. Liver recipients who experience rejection within 3 weeks after transplantation with OKT3 prophylaxis recover their T cells by postoperative day 10 despite complete initial clearance.

We sought to analyze the role of proinflammatory and Th‐1 cytokines in T cell recovery and rejection after liver transplantation with OKT3 prophylaxis. In plasma samples from 32 patients, we measured TNFα, IL1β, and IL6 (before transplant and on postoperative days 1, 2 and 3) and IL2, IFNγ, sIL2R and sICAM (postoperative days 5, 7 and 10) and examined possible correlations with T‐cell recovery and occurrence of rejection within 3 weeks.

TNFα, IL1β, and IL6 did not correlate with T‐cell recovery. In patients who rejected, IL2 and IFNγ on postoperative days 5 and 7 correlated with degree of T‐cell recovery by day 10; a significant rise in sIL2R over time also correlated with T‐cell recovery in this group.

ur results emphasize the role of Th‐1 cytokines in rejection following OKT3 induction and suggest that markers of T cell activation may predict risk.
GM‐CSF production from human airway smooth muscle cells is potentiated by human serum
Authors: Sukkar Maria B. , Hughes J. Margaret , Johnson Peter R. A. , Armour Carol L.
Published: July 2002

Recent evidence suggests that airway smooth muscle cells (ASMC) actively participate in the airway inflammatory process in asthma. Interleukin–1β (IL–1β) and tumour necrosis factor–α (TNF–α) induce ASMC to release inflammatory mediators in vitro. ASMC mediator release
in vivo, however, may be influenced by features of the allergic asthmatic phenotype. We determined whether; (1) allergic asthmatic serum (AAS) modulates ASMC mediator release in response to IL–1β and TNF–α, and (2) IL–1β/TNF–α prime ASMC to release mediators in response to AAS. IL–5 and GMCSF were quantified by ELISA in culture supernatants of; (1) ASMC pre‐incubated with either AAS, non‐allergic non‐asthmatic serum (NAS) or MonomedTM (a serum substitute) and subsequently stimulated with IL–1β and TNF–α and (2) ASMC stimulated with IL–1β/TNF–α and subsequently exposed to either AAS, NAS or MonomedTM. IL‐1g and TNF–α induced GM‐CSF release in ASMC pre‐incubated with AAS was not greater than that in ASMC pre‐incubated with NAS or MonomedTM. IL–1β and TNF–α, however, primed ASMC to release GM‐CSF in response to human serum. GM‐CSF production following IL–1β/TNF–α and serum exposure (AAS or NAS) was significantly greater than that following IL–1β /TNF–α and MonomedTM exposure or IL–1β/TNF–α exposure only. Whilst the potentiating effects of human serum were not specific to allergic asthma, these findings suggest that the secretory capacity of ASMC may be up‐regulated during exacerbations of asthma, where there is evidence of vascular leakage.
Expression and in vitro properties of guinea pig IL‐5: Comparison to human and murine orthologs
Authors: Scott Clay W , Budzilowicz Carol , Hubbs Stephen J. , Stein Mark , Sobotka-Briner Cindy , Wilkins Deidre E.
Published: July 2002

Interleukin‐5 (IL‐5) is a key mediator of eosinophilic inflammation. The biological role of this cytokine in an allergic airway inflammatory response has been widely demonstrated in guinea pigs, yet the interaction of guinea pig IL‐5 (gpIL‐5) with its receptor has not been studied. Experiments were performed to quantitate the interaction of gpIL‐5 with gpIL‐5r and to compare this affinity with that of hIL‐5 and mIL‐5 and their cognate receptors. The cross‐species affinity and agonist efficacy were evaluated to see if gpIL‐5r had a restricted species reactivity (as is the case with mIL‐5r) or did not distinguish between IL‐5 orthologs (similar to hIL‐5r). gpIL‐5 was cloned using mRNA isolated from cells obtained by bronchoalveolar lavage. Recombinant gpIL‐5 was expressed in T.ni insect cells and purified from spent media. Binding assays were performed using insect cells expressing hIL‐5rαβ or gpIL‐5rαβ1 as previously described (Cytokine, 12:858–866, 2000) or using B13 cells which express mIL‐5r. The agonist potency and efficacy properties of each IL‐5 ortholog were evaluated by quantitating the proliferative response of hum an TF‐1 cells and murine B13 cells. gpIL‐5 bound with high affinity to recombinant gpIL‐5r as demonstrated by displacing [125I]hIL‐5
(Ki = 160 pM). gpIL‐5 also bound to hIL‐5r with high affinity
(Ki = 750 pM). hIL‐5 and mIL‐5 showed similar, high‐affinity binding profiles to both gpIL‐5r and hIL‐5r. In contrast, gpIL‐5 and hIL5 did not bind to the mIL‐5r as demonstrated by an inability to displace
[125I]mIL‐5, even at 1000‐fold molar excess. These differences in affinity for IL‐5r orthologs correlated with bioassay results: human TF1 cells showed roughly com parable proliferative responses to guinea pig, hum an and murine IL‐5 whereas murine B13 cells showed a strong preference for murine over guinea pig and human IL‐5(EC50 = 1.9, 2200 and 720 pM, respectively). Recombinant gpIL‐5 binds to the gpIL‐5r with high affinity, similar to that seen with the human ligand‐receptor pair. gpIL‐5r and hIL‐5r do not distinguish between the three IL‐5 orthologs whereas mIL‐5r has restricted specificity for its cognate ligand.
Effect of an inhaled glucocorticoid on reactive oxygen species production by bronchoalveolar lavage cells from smoking COPD patients
Authors: Verhoeven Gert T. , Wijkhuijs Annemarie J.M. , Hooijkaas Herbert , Hoogsteden Henk C. , Sluiter Wim
Published: July 2002

Oxidative stress in the lung is important in the pathogenesis of COPD. Published data indicate that glucocorticoids inhibit blood cells in their capacity to produce reactive oxygen species (ROS). We investigated the effect of Fluticasone propionate (FP) on the ROS production capabilities of pulmonary cells. Bronchoalveolar lavage (BAL) was performed in smoking COPD patients, before and after a six month, placebo‐controlled treatment with FP. BAL cells were stimulated with phorbol myristrate acetate (PMA) alone, and together with superoxide dismutase (SOD). From kinetic plots of ferricytochrome‐c conversion we calculated the maximal rate of superoxide production: Vmax. We also examined BAL cell subsets and performed correlation analyses on ROS production and relevant clinical determinants. Paired results were obtained from 6 FP‐ and 9 placebo‐treated patients. No significant change of Vmax was found in both patient groups. Also BAL cellularity was unchanged. Correlation analyses showed a significant (inverse) association
of Vmax with the number of cigarettes smoked per day. We concluded that a potent inhaled glucocorticoid had no effect on the ROS production capability of BAL cells from smoking COPD patients. Apparently, heavy smoking impaired the ability of alveolar macrophages to produce ROS, which was not further decreased by FP.