bluuebunny/crossref_metadata_2025 huggingface dataset:
Visual memory-deficit amnesia: A distinct amnesic presentation and etiology
Authors: Rubin David C. , Greenberg Daniel L.
Published: July 2002

We describe a form of amnesia, which we have called visual memory-deficit amnesia, that is caused by damage to areas of the visual system that store visual information. Because it is caused by a deficit in access to stored visual material and not by an impaired ability to encode or retrieve new material, it has the otherwise infrequent properties of a more severe retrograde than anterograde amnesia with no temporal gradient in the retrograde amnesia. Of the 11 cases of long-term visual memory loss found in the literature, all had amnesia extending beyond a loss of visual memory, often including a near total loss of pretraumatic episodic memory. Of the 6 cases in which both the severity of retrograde and anterograde amnesia and the temporal gradient of the retrograde amnesia were noted, 4 had a more severe retrograde amnesia with no temporal gradient and 2 had a less severe retrograde amnesia with a temporal gradient.
The growth of demand will limit output growth for food over the next quarter century
Authors: Johnson D. Gale
Published: July 2002

The rate of growth of world food demand will be much slower
for 1990–2010 than it was for the prior three decades. The major
factor determining the increase in food demand is population growth.
Income growth has a much smaller effect. From 1960 to 1990, population
growth accounted for approximately three fourths of the growth in
demand or use of grain. For 1990–2010, it is anticipated that
population growth will account for nearly all of the increase in world
demand for grain. The rate of population growth from 1990 to 2020 is
projected to be at an annual rate of 1.3% compared with 1.9% for 1960
to 1990—a decline of more than 30%. World per capita use of grain
will increase very little—perhaps by 4%. The increase in grain use is
projected to be 40% less than in 1960–1990. It is anticipated that
real grain prices will decline during the period, although not nearly
as much as the 40% decline in the previous three decades. Concern has
been expressed concerning the deterioration of the quality and
productivity of the world’s farmland. A study for China and Indonesia
indicates that there has been no significant change in the productive
capacity of the land over the past 50 years. Contrary to numerous
claims, the depth of the topsoil has not changed, indicating that
erosion has had little or no impact.
Normal growth and development in the absence of hepatic insulin-like growth factor I
Authors: Yakar Shoshana , Liu Jun-Li , Stannard Bethel , Butler Andrew , Accili Domenici , Sauer Brian , LeRoith Derek
Published: July 2002

The somatomedin hypothesis proposed that insulin-like growth factor I (IGF-I) was a hepatically derived circulating mediator of growth hormone and is a crucial factor for postnatal growth and development. To reassess this hypothesis, we have used the Cre/
loxP
recombination system to delete the
igf1
gene exclusively in the liver.
igf1
gene deletion in the liver abrogated expression of
igf1
mRNA and caused a dramatic reduction in circulating IGF-I levels. However, growth as determined by body weight, body length, and femoral length did not differ from wild-type littermates. Although our model proves that hepatic IGF-I is indeed the major contributor to circulating IGF-I levels in mice it challenges the concept that circulating IGF-I is crucial for normal postnatal growth. Rather, our model provides direct evidence for the importance of the autocrine/paracrine role of IGF-I.
Five-transmembrane domains appear sufficient for a G protein-coupled receptor: Functional five-transmembrane domain chemokine receptors
Authors: Ling Kun , Wang Ping , Zhao Jian , Wu Ya-Lan , Cheng Zhi-Jie , Wu Guo-Xiang , Hu Wei , Ma Lan , Pei Gang
Published: July 2002

The putative seven-transmembrane (TM) domains have been the structural hallmark for the superfamily of heterotrimeric G protein-coupled receptors (GPCRs) that regulate a variety of cellular functions by mediating a large number of extracellular signals. Five-TM GPCR mutants of chemokine receptor CCR5 and CXCR4, the N-terminal segment of which connected directly to TM3 as a result of a deletion of TM1–2 and the first intracellular and extracellular loops, have been obtained in this study. Laser confocal microscopy and flow cytometry analysis revealed that these five-TM mutant GPCRs were expressed stably on the cell surface after transfection into human embryonic kidney 293 cells. The five-TM CCR5 and CXCR4 functioned as normal chemokine receptors in mediating chemokine-stimulated chemotaxis, Ca
2+
influx, and activation of pertussis toxin-sensitive G proteins. Like the wild-type GPCRs, the five-TM mutant receptors also underwent agonist-dependent internalization and desensitization and were subjected to regulation by GPCR kinases and arrestins. Our study indicates that five-TM domains, at least in the case of CCR5 and CXCR4, appear to meet the minimum structural requirements for a functional GPCR and suggests possible existence of functional five-TM GPCRs in nature during evolution.
The oxyhemoglobin reaction of nitric oxide
Authors: Gow Andrew J. , Luchsinger Benjamin P. , Pawloski John R. , Singel David J. , Stamler Jonathan S.
Published: July 2002

The oxidation of nitric oxide (NO) to nitrate by oxyhemoglobin is a fundamental reaction that shapes our understanding of NO biology. This reaction is considered to be the major pathway for NO elimination from the body; it is the basis for a prevalent NO assay; it is a critical feature in the modeling of NO diffusion in the circulatory system; and it informs a variety of therapeutic applications, including NO-inhalation therapy and blood substitute design. Here we show that, under physiological conditions, this reaction is of little significance. Instead, NO preferentially binds to the minor population of the hemoglobin’s vacant hemes in a cooperative manner, nitrosylates hemoglobin thiols, or reacts with liberated superoxide in solution. In the red blood cell, superoxide dismutase eliminates superoxide, increasing the yield of
S
-nitrosohemoglobin and nitrosylated hemes. Hemoglobin thus serves to regulate the chemistry of NO and maintain it in a bioactive state. These results represent a reversal of the conventional view of hemoglobin in NO biology and motivate a reconsideration of fundamental issues in NO biochemistry and therapy.
Gender-specific frequency of background somatic mutations at the hypoxanthine phosphoribosyltransferase locus in cord blood T lymphocytes from preterm newborns
Authors: Yoshioka Makoto , Vacek Pamela M. , Poseno Tina , Silver Robert , Finette Barry A.
Published: July 2002

Limited information is available regarding the frequency, spectrum, and clinical relevance of somatic mutations in the developing fetus. The goal of this study was to determine somatic mutant frequencies (Mfs) at the hypoxanthine phosphoribosyltransferase (HPRT) reporter gene in cord blood T lymphocytes from preterm infants to gain insight intoin uteromutational events. Mf determinations were made by using theHPRTT cell cloning assay on cord blood samples from 52 preterm infants. Natural logarithm Mfs (lnMfs) from preterm infants were compared with results from our database for full-term infants. Our analysis revealed higher lnMfs in cord blood T lymphocytes from preterm compared with full-term infants (P= 0.008). In addition, preterm females had significantly higher lnMfs compared with full-term females (P< 0.001), whereas preterm males were found to have significantly lower lnMfs than preterm females (P= 0.005). Regression analyses also demonstrate a significant relationship between lnMf and gestational age for preterm females that does not exist for preterm males. These results demonstrate the gender-specific association between Mf and age in humans.
The catalytic sites of 20S proteasomes and their role in subunit maturation: A mutational and crystallographic study
Authors: Groll Michael , Heinemeyer Wolfgang , Jäger Sibylle , Ullrich Tobias , Bochtler Matthias , Wolf Dieter H. , Huber Robert
Published: July 2002

We present a biochemical and crystallographic characterization of
active site mutants of the yeast 20S proteasome with the aim to
characterize substrate cleavage specificity, subunit intermediate
processing, and maturation. β1(Pre3), β2(Pup1), and β5(Pre2) are
responsible for the postacidic, tryptic, and chymotryptic activity,
respectively. The maturation of active subunits is independent of the
presence of other active subunits and occurs by intrasubunit autolysis.
The propeptides of β6(Pre7) and β7(Pre4) are intermediately
processed to their final forms by β2(Pup1) in the wild-type enzyme
and by β5(Pre2) and β1(Pre3) in the β2(Pup1) inactive mutants. A
role of the propeptide of β1(Pre3) is to prevent acetylation and
thereby inactivation. A gallery of proteasome mutants that contain
active site residues in the context of the inactive subunits
β3(Pup3), β6(Pre7), and β7(Pre4) show that the presence of Gly-1,
Thr1, Asp17, Lys33, Ser129, Asp166, and Ser169 is not sufficient to
generate activity.
SMN mutants of spinal muscular atrophy patients are defective in binding to snRNP proteins
Authors: Pellizzoni Livio , Charroux Bernard , Dreyfuss Gideon
Published: July 2002

Spinal muscular atrophy (SMA) is a common motor neuron degenerative disease and the leading genetic cause of death of young children. The survival of motor neurons (
SMN
) gene, the SMA disease gene, is homozygously deleted or mutated in more than 98% of SMA patients. The SMN protein interacts with itself, with SMN-interacting protein 1, and with several spliceosomal small nuclear ribonucleoprotein (snRNP) Sm proteins. A complex containing SMN plays a critical role in spliceosomal snRNP assembly and in pre-mRNA splicing. SMN mutants found in SMA patients show reduced self-association and lack the capacity to regenerate the splicing machinery. Here we demonstrate that SMN mutants found in SMA patients are defective in binding to Sm proteins. Moreover, we show that SMN, but not mutants found in SMA patients, can form large oligomers and that SMN oligomerization is required for high-affinity binding to spliceosomal snRNP Sm proteins. These findings directly link the impaired interaction between SMN and Sm proteins to a defect in snRNP metabolism and to SMA.
Ovochymase, a
Xenopus
laevis
egg extracellular protease, is translated as part of an unusual polyprotease
Authors: Lindsay LeAnn L. , Yang Joy C. , Hedrick Jerry L.
Published: July 2002

Ovochymase, an extracellular
Xenopus
laevis
egg serine active-site protease with chymotrypsin-like (Phe-X) substrate specificity, is released during egg activation. Molecular cloning results revealed that ovochymase is translated as part of an unusual polyprotein proenzyme. In addition to the ovochymase protease domain at the C terminus of the deduced amino acid sequence, two unrelated serine protease domains were present, each with apparent trypsin-like (Arg/Lys-X) substrate specificity, and thus, they were designated ovotryptase1 (at the N terminus) and ovotryptase2 (a mid domain). Also, a total of five CUB domains were interspersed between the protease domains. The presence of a hydrophobic signal sequence indicated that the polyprotein was secreted. Immunolocalization and Western blot studies of all three proteases showed that they are all present in the perivitelline space of unactivated eggs, apparently as proenzymes processed away from the original polyprotein. Western blot analysis also showed that the vast majority of the proteases in ovary, eggs, and embryos were present as the proenzyme forms, suggesting that the functions of these proteases depend on very limited levels of activation.
Spontaneous deleterious mutation in
Arabidopsis thaliana
Authors: Schultz Stewart T. , Lynch Michael , Willis John H.
Published: July 2002

The frequency and selective impact of deleterious mutations are fundamental parameters in evolutionary theory, yet they have not been directly measured in a plant species. To estimate these quantities, we allowed spontaneous mutations to accumulate for 10 generations in 1,000 inbred lines of the annual, self-fertilizing plant
Arabidopsis thaliana
and assayed fitness differences between generations 0 and 10 in a common garden. Germination rate, fruit set, and number of seeds per fruit each declined by less than 1% per generation in the mutation lines, and total fitness declined by 0.9% per generation. Among-line variances increased in the mutation lines for all traits. Application of an equal-effects model suggests a downwardly biased genomic deleterious mutation rate of 0.1 and a upwardly biased effect of individual mutations on total fitness of 20%. This genomic deleterious mutation rate is consistent with estimates of nucleotide substitution rates in flowering plants, the genome size of
Arabidopsis
, and the equilibrium inbreeding depression observed in this highly selfing plant species.
Growth ofToxoplasma gondiiis inhibited by aryloxyphenoxypropionate herbicides targeting acetyl-CoA carboxylase
Authors: Zuther E. , Johnson J. J. , Haselkorn R. , McLeod R. , Gornicki P.
Published: July 2002

Aryloxyphenoxypropionates, inhibitors of the plastid acetyl-CoA carboxylase (ACC) of grasses, also inhibitToxoplasma gondiiACC. Clodinafop, the most effective of the herbicides tested, inhibits growth ofT. gondiiin human fibroblasts by 70% at 10 μM in 2 days and effectively eliminates the parasite in 2–4 days at 10–100 μM. Clodinafop is not toxic to the host cell even at much higher concentrations. Parasite growth inhibition by different herbicides is correlated with their ability to inhibit ACC enzyme activity, suggesting that ACC is a target for these agents. Fragments of genes encoding the biotin carboxylase domain of multidomain ACCs ofT. gondii,Plasmodium falciparum,Plasmodium knowlesi, andCryptosporidium parvumwere sequenced. OneT. gondiiACC (ACC1) amino acid sequence clusters withP. falciparumACC,P. knowlesiACC, and the putativeCyclotella crypticachloroplast ACC. Another sequence (ACC2) clusters with that ofC. parvumACC, probably the cytosolic form.
Inosine stimulates extensive axon collateral growth in the rat corticospinal tract after injury
Authors: Benowitz Larry I. , Goldberg David E. , Madsen Joseph R. , Soni Deepa , Irwin Nina
Published: July 2002

The purine nucleoside inosine has been shown to induce axon outgrowth from primary neurons in culture through a direct intracellular mechanism. For this study, we investigated the effects of inosine
in vivo
by examining whether it would stimulate axon growth after a unilateral transection of the corticospinal tract. Inosine applied with a minipump to the rat sensorimotor cortex stimulated intact pyramidal cells to undergo extensive sprouting of their axons into the denervated spinal cord white matter and adjacent neuropil. Axon growth was visualized by anterograde tracing with biotinylated dextran amine and by immunohistochemistry with antibodies to GAP-43. Thus, inosine, a naturally occurring metabolite without known side effects, might help to restore essential circuitry after injury to the central nervous system.
Inhibition of human telomerase in immortal human cells leads to progressive telomere shortening and cell death
Authors: Herbert B.-S. , Pitts A. E. , Baker S. I. , Hamilton S. E. , Wright W. E. , Shay J. W. , Corey D. R.
Published: July 2002

The correlation between telomerase activity and human tumors has led to the hypothesis that tumor growth requires reactivation of telomerase and that telomerase inhibitors represent a class of chemotherapeutic agents. Herein, we examine the effects of inhibition of telomerase inside human cells. Peptide nucleic acid and 2′
-O-
MeRNA oligomers inhibit telomerase, leading to progressive telomere shortening and causing immortal human breast epithelial cells to undergo apoptosis with increasing frequency until no cells remain. Telomere shortening is reversible: if inhibitor addition is terminated, telomeres regain their initial lengths. Our results validate telomerase as a target for the discovery of anticancer drugs and supply general insights into the properties that successful agents will require regardless of chemical type. Chemically similar oligonucleotides are in clinical trials and have well characterized pharmacokinetics, making the inhibitors we describe practical lead compounds for testing for an antitelomerase chemotherapeutic strategy.
STEAP: A prostate-specific cell-surface antigen highly expressed in human prostate tumors
Authors: Hubert Rene S. , Vivanco Igor , Chen Emily , Rastegar Shiva , Leong Kahan , Mitchell Steve C. , Madraswala Rashida , Zhou Yanhong , Kuo James , Raitano Arthur B. , Jakobovits Aya , Saffran Douglas C. , Afar Daniel E. H.
Published: July 2002

In search of novel genes expressed in metastatic prostate cancer, we subtracted cDNA isolated from benign prostatic hypertrophic tissue from cDNA isolated from a prostate cancer xenograft model that mimics advanced disease. One novel gene that is highly expressed in advanced prostate cancer encodes a 339-amino acid protein with six potential membrane-spanning regions flanked by hydrophilic amino- and carboxyl-terminal domains. This structure suggests a potential function as a channel or transporter protein. This gene, named
STEAP
for
s
ix-
t
ransmembrane
e
pithelial
a
ntigen of the
p
rostate, is expressed predominantly in human prostate tissue and is up-regulated in multiple cancer cell lines, including prostate, bladder, colon, ovarian, and Ewing sarcoma. Immunohistochemical analysis of clinical specimens demonstrates significant STEAP expression at the cell–cell junctions of the secretory epithelium of prostate and prostate cancer cells. Little to no staining was detected at the plasma membranes of normal, nonprostate human tissues, except for bladder tissue, which expressed low levels of STEAP at the cell membrane. Protein analysis located STEAP at the cell surface of prostate-cancer cell lines. Our results support STEAP as a cell-surface tumor-antigen target for prostate cancer therapy and diagnostic imaging.
PEG-3, a nontransforming cancer progression gene, is a positive regulator of cancer aggressiveness and angiogenesis
Authors: Su Zao-Zhong , Goldstein Neil I. , Jiang Hongping , Wang Mei-Nai , Duigou Gregory J. , Young Charles S. H. , Fisher Paul B.
Published: July 2002

Cancer is a progressive disease culminating in acquisition of metastatic potential by a subset of evolving tumor cells. Generation of an adequate blood supply in tumors by production of new blood vessels, angiogenesis, is a defining element in this process. Although extensively investigated, the precise molecular events underlying tumor development, cancer progression, and angiogenesis remain unclear. Subtraction hybridization identified a genetic element, progression elevated gene-3 (PEG-3), whose expression directly correlates with cancer progression and acquisition of oncogenic potential by transformed rodent cells. We presently demonstrate that forced expression of PEG-3 in tumorigenic rodent cells, and in human cancer cells, increases their oncogenic potential in nude mice as reflected by a shorter tumor latency time and the production of larger tumors with increased vascularization. Moreover, inhibiting endogenous PEG-3 expression in progressed rodent cancer cells by stable expression of an antisense expression vector extinguishes the progressed cancer phenotype. Cancer aggressiveness of PEG-3 expressing rodent cells correlates directly with increased RNA transcription, elevated mRNA levels, and augmented secretion of vascular endothelial growth factor (VEGF). Furthermore, transient ectopic expression of PEG-3 transcriptionally activates VEGF in transformed rodent and human cancer cells. Taken together these data demonstrate that PEG-3 is a positive regulator of cancer aggressiveness, a process regulated by augmented VEGF production. These studies also support an association between expression of a single nontransforming cancer progression-inducing gene, PEG-3, and the processes of cancer aggressiveness and angiogenesis. In these contexts, PEG-3 may represent an important target molecule for developing cancer therapeutics and inhibitors of angiogenesis.
Ablation of P/Q-type Ca
2+
channel currents, altered synaptic transmission, and progressive ataxia in mice lacking the α
1A
-subunit
Authors: Jun Kisun , Piedras-Rentería Erika S. , Smith Stephen M. , Wheeler David B. , Lee Seong Beom , Lee Taehoon G. , Chin Hemin , Adams Michael E. , Scheller Richard H. , Tsien Richard W. , Shin Hee-Sup
Published: July 2002

The Ca
2+
channel α
1A
-subunit is a voltage-gated, pore-forming membrane protein positioned at the intersection of two important lines of research: one exploring the diversity of Ca
2+
channels and their physiological roles, and the other pursuing mechanisms of ataxia, dystonia, epilepsy, and migraine. α
1A
-Subunits are thought to support both P- and Q-type Ca
2+
channel currents, but the most direct test, a null mutant, has not been described, nor is it known which changes in neurotransmission might arise from elimination of the predominant Ca
2+
delivery system at excitatory nerve terminals. We generated α
1A
-deficient mice (α
1A
−/−
) and found that they developed a rapidly progressive neurological deficit with specific characteristics of ataxia and dystonia before dying ≈3–4 weeks after birth. P-type currents in Purkinje neurons and P- and Q-type currents in cerebellar granule cells were eliminated completely whereas other Ca
2+
channel types, including those involved in triggering transmitter release, also underwent concomitant changes in density. Synaptic transmission in α
1A
−/−
hippocampal slices persisted despite the lack of P/Q-type channels but showed enhanced reliance on N-type and R-type Ca
2+
entry. The α
1A
−/−
mice provide a starting point for unraveling neuropathological mechanisms of human diseases generated by mutations in α
1A
.
The
Arabidopsis thaliana
proton transporters, AtNhx1 and Avp1, can function in cation detoxification in yeast
Authors: Gaxiola Roberto A. , Rao Rajini , Sherman Amir , Grisafi Paula , Alper Seth L. , Fink Gerald R.
Published: July 2002

Overexpression of the
Arabidopsis thaliana
vacuolar
H
+
-pyrophosphatase (
AVP1
) confers salt
tolerance to the salt-sensitive
ena1
mutant of
Saccharomyces cerevisiae
. Suppression of salt sensitivity
requires two ion transporters, the Gef1 Cl
−
channel and
the Nhx1 Na
+
/H
+
exchanger. These two proteins
colocalize to the prevacuolar compartment of yeast and are thought to
be required for optimal acidification of this compartment.
Overexpression of
AtNHX1
, the plant homologue of the yeast
Na
+
/H
+
exchanger, suppresses some of the
mutant phenotypes of the yeast
nhx1
mutant. Moreover, the
level of
AtNHX1
mRNA in
Arabidopsis
is
increased in the presence of NaCl. The regulation of
AtNHX1
by NaCl and the ability of the plant gene to suppress the yeast
nhx1
mutant suggest that the mechanism by which cations are
detoxified in yeast and plants may be similar.
A zinc finger truncation of murine WT1 results in the characteristic urogenital abnormalities of Denys–Drash syndrome
Authors: Patek Charles E. , Little Melissa H. , Fleming Stewart , Miles Colin , Charlieu Jean-Paul , Clarke Alan R. , Miyagawa Kiyoshi , Christie Sheila , Doig Jennifer , Harrison David J. , Porteous David J. , Brookes Anthony J. , Hooper Martin L. , Hastie Nicholas D.
Published: July 2002

The Wilms tumor-suppressor gene,
WT1
, plays a key role in urogenital development, and WT1 dysfunction is implicated in both neoplastic (Wilms tumor, mesothelioma, leukemias, and breast cancer) and nonneoplastic (glomerulosclerosis) disease. The analysis of diseases linked specifically with
WT1
mutations, such as Denys–Drash syndrome (DDS), can provide valuable insight concerning the role of WT1 in development and disease. DDS is a rare childhood disease characterized by a nephropathy involving mesangial sclerosis, XY pseudohermaphroditism, and/or Wilms tumor (WT). DDS patients are constitutionally heterozygous for exonic point mutations in
WT1
, which include mutations predicted to truncate the protein within the C-terminal zinc finger (ZF) region. We report that heterozygosity for a targeted murine
Wt1
allele,
Wt1
tmT396
, which truncates ZF3 at codon 396, induces mesangial sclerosis characteristic of DDS in adult heterozygous and chimeric mice. Male genital defects also were evident and there was a single case of Wilms tumor in which the transcript of the nontargeted allele showed an exon 9 skipping event, implying a causal link between
Wt1
dysfunction and Wilms tumorigenesis in mice. However, the mutant WT1
tmT396
protein accounted for only 5% of WT1 in both heterozygous embryonic stem cells and the WT. This has implications regarding the mechanism by which the mutant allele exerts its effect.
Mechanism of the cleavage specificity of Alzheimer’s disease γ-secretase identified by phenylalanine-scanning mutagenesis of the transmembrane domain of the amyloid precursor protein
Authors: Lichtenthaler Stefan F. , Wang Rong , Grimm Heike , Uljon Sacha N. , Masters Colin L. , Beyreuther Konrad
Published: July 2002

Proteolytic processing of the amyloid precursor protein by β-secretase yields A4CT (C99), which is cleaved further by the as yet unknown γ-secretase, yielding the β-amyloid (Aβ) peptide with 40 (Aβ
40
) or 42 residues (Aβ
42
). Because the position of γ-secretase cleavage is crucial for the pathogenesis of Alzheimer’s disease, we individually replaced all membrane-domain residues of A4CT outside the Aβ domain with phenylalanine, stably transfected the constructs in COS7 cells, and determined the effect of these mutations on the cleavage specificity of γ-secretase (Aβ
42
/Aβ
40
ratio). Compared with wild-type A4CT, mutations at Val-44, Ile-47, and Val-50 led to decreased Aβ
42
/Aβ
40
ratios, whereas mutations at Thr-43, Ile-45, Val-46, Leu-49, and Met-51 led to increased Aβ
42
/Aβ
40
ratios. A massive effect was observed for I45F (34-fold increase) making this construct important for the generation of animal models for Alzheimer’s disease. Unlike the other mutations, A4CT-V44F was processed mainly to Aβ
38
, as determined by mass spectrometry. Our data provide a detailed model for the active site of γ-secretase: γ-secretase interacts with A4CT by binding to one side of the α-helical transmembrane domain of A4CT. Mutations in the transmembrane domain of A4CT interfere with the interaction between γ-secretase and A4CT and, thus, alter the cleavage specificity of γ-secretase.
Deduction of consensus binding sequences on proteins that bind IIA
Glc
of the phospho
enol
pyruvate:sugar phosphotransferase system by cysteine scanning mutagenesis of
Escherichia coli
lactose permease
Authors: Sondej Melissa , Sun Jianzhong , Seok Yeong-Jae , Kaback H. Ronald , Peterkofsky Alan
Published: July 2002

Mediated by the protein IIA
Glc
, the phospho
enol
pyruvate:sugar phosphotransferase system plays a role in the regulation of activity of other sugar transport systems in
Escherichia coli
. By using a direct binding assay, a collection of single-Cys replacement mutants in cytoplasmic loops of lactose permease were evaluated for their capacity to bind IIA
Glc
. Selected Cys replacements in loops IV/V or VI/VII result in loss of binding activity. Analysis of the mutagenesis results together with multiple sequence alignments of a family of proteins that interacts with IIA
Glc
provides the basis for developing two regions of consensus sequence in those partner proteins necessary for binding to IIA
Glc
. The requirement for two interaction regions is interpreted in the regulatory framework of a substrate-dependent conformational change that brings those two regions into an orientation optimal for binding IIA
Glc
.
Comparing
in vitro
,
in situ
, and
in vivo
experimental data in a three-dimensional model of mammalian cochlear mechanics
Authors: Kolston Paul J.
Published: July 2002

Normal mammalian hearing is refined by amplification of the motion of the cochlear partition. This partition, comprising the organ of Corti sandwiched between the basilar and tectorial membranes, contains the outer hair cells that are thought to drive this amplification process. Force generation by outer hair cells has been studied extensively
in vitro
and
in situ
, but, to understand cochlear amplification fully, it is necessary to characterize the role played by each of the components of the cochlear partition
in vivo
. Observations of cochlear partition motion
in vivo
are severely restricted by its inaccessibility and sensitivity to surgical trauma, so, for the present study, a computer model has been used to simulate the operation of the cochlea under different experimental conditions. In this model, which uniquely retains much of the three-dimensional complexity of the real cochlea, the motions of the basilar and tectorial membranes are fundamentally different during
in situ
- and
in vivo
-like conditions. Furthermore, enhanced outer hair cell force generation
in vitro
leads paradoxically to a decrease in the gain of the cochlear amplifier during sound stimulation to the model
in vivo
. These results suggest that it is not possible to extrapolate directly from experimental observations made
in vitro
and
in situ
to the normal operation of the intact organ
in vivo
.
Differential quantal release of histamine and 5-hydroxytryptamine from mast cells of vesicular monoamine transporter 2 knockout mice
Authors: Travis Eric R. , Wang Yan-Min , Michael Darren J. , Caron Marc G. , Wightman R. Mark
Published: July 2002

The recent availability of mice lacking the neuronal form of the
vesicular monoamine transporter 2 (VMAT2) affords the opportunity to
study its roles in storage and release. Carbon fiber microelectrodes
were used to measure individual secretory events of histamine and
5-hydroxytryptamine (5-HT) from VMAT2-expressing mast cells as a model
system for quantal release. VMAT2 is indispensable for monoamine
storage because mast cells from homozygous (VMAT2
−/−
)
mice, while undergoing granule-cell fusion, do not release monoamines.
Cells from heterozygous animals (VMAT2
+/−
) secrete lower
amounts of monoamine per granule than cells from wild-type controls.
Investigation of corelease of histamine and 5-HT from granules in
VMAT2
+/−
cells revealed 5-HT quantal size was reduced more
than that of histamine. Thus, although vesicular transport is the
limiting factor determining quantal size of 5-HT and histamine release,
intragranular association with the heparin matrix also plays a
significant role.
Chloroplast protein and centrosomal genes, a tRNA intron, and odd telomeres in an unusually compact eukaryotic genome, the cryptomonad nucleomorph
Authors: Zauner Stefan , Fraunholz Martin , Wastl Jürgen , Penny Susanne , Beaton Margaret , Cavalier-Smith Thomas , Maier Uwe-G. , Douglas Susan
Published: July 2002

Cells of several major algal groups are evolutionary chimeras of two radically different eukaryotic cells. Most of these “cells within cells” lost the nucleus of the former algal endosymbiont. But after hundreds of millions of years cryptomonads still retain the nucleus of their former red algal endosymbiont as a tiny relict organelle, the nucleomorph, which has three minute linear chromosomes, but their function and the nature of their ends have been unclear. We report extensive cryptomonad nucleomorph sequences (68.5 kb), from one end of each of the three chromosomes of
Guillardia theta.
Telomeres of the nucleomorph chromosomes differ dramatically from those of other eukaryotes, being repeats of the 23-mer sequence (AG)
7
AAG
6
A, not a typical hexamer (commonly TTAGGG). The subterminal regions comprising the rRNA cistrons and one protein-coding gene are exactly repeated at all three chromosome ends. Gene density (one per 0.8 kb) is the highest for any cellular genome. None of the 38 protein-coding genes has spliceosomal introns, in marked contrast to the chlorarachniophyte nucleomorph. Most identified nucleomorph genes are for gene expression or protein degradation; histone, tubulin, and putatively centrosomal
ranbpm
genes are probably important for chromosome segregation. No genes for primary or secondary metabolism have been found. Two of the three tRNA genes have introns, one in a hitherto undescribed location. Intergenic regions are exceptionally short; three genes transcribed by two different RNA polymerases overlap their neighbors. The reported sequences encode two essential chloroplast proteins, FtsZ and rubredoxin, thus explaining why cryptomonad nucleomorphs persist.
The Nef protein of HIV-1 associates with rafts and primes T cells for activation
Authors: Wang Jen-Kuei , Kiyokawa Etsuko , Verdin Eric , Trono Didier
Published: July 2002

The Nef protein is an important virulence factor of primate lentiviruses, yet the mechanisms by which it exerts this influence are imperfectly understood. Here, using an inducible system, we demonstrate that Nef increases IL-2 secretion from T cells stimulated via CD3 or CD28. This effect requires the conservation of the Nef myristoylation signal and SH3-binding proline-based motif. Together with several proteins involved in the initiation and propagation of T cell signaling, Nef associates with membrane microdomains known as rafts. The Nef-mediated superinduction of IL-2 reflects the activation of both NFAT and NFκB. Accordingly, Nef also enhances HIV-1 transcription in response to CD3 or CD28 stimulation. Nef-induced IL-2 hyperresponsiveness is also observed in primary CD4 lymphocytes. Overall, these data suggest that Nef acts at the level of rafts to prime T cells for activation. Likely consequences of this effect are the promotion of HIV-1 replication and the facilitation of virus spread.
Nuclear clusterin/XIP8, an x-ray-induced Ku70-binding protein that signals cell death
Authors: Yang Chin-Rang , Leskov Konstantin , Hosley-Eberlein Kelly , Criswell Tracy , Pink John J. , Kinsella Timothy J. , Boothman David A.
Published: July 2002

Clusterin [CLU, a.k.a. TRPM-2, SGP-2, or ionizing radiation (IR)-induced protein-8 (XIP8)] was implicated in apoptosis, tissue injury, and aging. Its function remains elusive. We reisolated CLU/XIP8 by yeast two-hybrid analyses using as bait the DNA double-strand break repair protein Ku70. We show that a delayed (2–3 days), low-dose (0.02–10 Gy) IR-inducible nuclear CLU/XIP8 protein coimmunoprecipitated and colocalized (by confocal microscopy)
in vivo
with Ku70/Ku80, a DNA damage sensor and key double-strand break repair protein, in human MCF-7:WS8 breast cancer cells. Overexpression of nuclear CLU/XIP8 or its minimal Ku70 binding domain (120 aa of CLU/XIP8 C terminus) in nonirradiated MCF-7:WS8 cells dramatically reduced cell growth and colony-forming ability concomitant with increased G
1
cell cycle checkpoint arrest and increased cell death. Enhanced expression and accumulation of nuclear CLU/XIP8-Ku70/Ku80 complexes appears to be an important cell death signal after IR exposure.
A DNA enzyme with
N
-glycosylase activity
Authors: Sheppard Terry L. , Ordoukhanian Phillip , Joyce Gerald F.
Published: July 2002

In vitro
evolution was used to develop a DNA enzyme that catalyzes the site-specific depurination of DNA with a catalytic rate enhancement of about 10
6
-fold. The reaction involves hydrolysis of the
N
-glycosidic bond of a particular deoxyguanosine residue, leading to DNA strand scission at the apurinic site. The DNA enzyme contains 93 nucleotides and is structurally complex. It has an absolute requirement for a divalent metal cation and exhibits optimal activity at about pH 5. The mechanism of the reaction was confirmed by analysis of the cleavage products by using HPLC and mass spectrometry. The isolation and characterization of an
N
-glycosylase DNA enzyme demonstrates that single-stranded DNA, like RNA and proteins, can form a complex tertiary structure and catalyze a difficult biochemical transformation. This DNA enzyme provides a new approach for the site-specific cleavage of DNA molecules.
Development and persistence of kindling epilepsy are impaired in mice lacking glial cell line-derived neurotrophic factor family receptor α2
Authors: Nanobashvili Avtandil , Airaksinen Matti S. , Kokaia Merab , Rossi Jari , Asztély Fredrik , Olofsdotter Klara , Mohapel Paul , Saarma Mart , Lindvall Olle , Kokaia Zaal
Published: July 2002

Seizure activity regulates gene expression for glial cell
line-derived neurotrophic factor (GDNF) and neurturin (NRTN), and their
receptor components, the transmembrane c-Ret tyrosine kinase and the
glycosylphosphatidylinositol-anchored GDNF family receptor (GFR) α1
and α2 in limbic structures. We demonstrate here that
epileptogenesis, as assessed in the hippocampal kindling model, is
markedly suppressed in mice lacking GFRα2. Moreover, at 6 to 8 wk
after having reached the epileptic state, the hyperexcitability is
lower in GFRα2 knock-out mice as compared with wild-type mice. These
results provide evidence that signaling through GFRα2 is involved in
mechanisms regulating the development and persistence of kindling
epilepsy. Our data suggest that GDNF and NRTN may modulate seizure
susceptibility by altering the function of hilar neuropeptide
Y-containing interneurons and entorhinal cortical afferents at dentate
granule cell synapses.
A habitat for psychrophiles in deep Antarctic ice
Authors: Price P. Buford
Published: July 2002

Microbes, some of which may be viable, have been found in ice cores
drilled at Vostok Station at depths down to ≈3,600 m, close to the
surface of the huge subglacial Lake Vostok. Two types of ice have been
found. The upper 3,500 m comprises glacial ice containing traces of
nutrients of aeolian origin including sulfuric acid, nitric acid,
methanosulfonic acid (MSA), formic acid, sea salts, and mineral grains.
Ice below ≈3,500 m comprises refrozen water from Lake Vostok,
accreted to the bottom of the glacial ice. Nutrients in the accretion
ice include salts and dissolved organic carbon. There is great interest
in searching for living microbes and especially for new species in
deepest Antarctic ice. I propose a habitat consisting of interconnected
liquid veins along three-grain boundaries in ice in which psychrophilic
bacteria can move and obtain energy and carbon from ions in solution.
In the accretion ice, with an age of a few 10
4
years and a
temperature a few degrees below freezing, the carbon and energy sources
in the veins can maintain significant numbers of cells per cubic
centimeter that are metabolizing but not multiplying. In the 4 ×
10
5
-year-old colder glacial ice, at least 1 cell per
cm
3
in acid veins can be maintained. With fluorescence
microscopy tuned to detect NADH in live organisms, motile bacteria
could be detected by direct scanning of the veins in ice samples.
Ice-core evidence of abrupt climate changes
Authors: Alley Richard B.
Published: July 2002

Ice-core records show that climate changes in the past
have been large, rapid, and synchronous over broad areas extending into
low latitudes, with less variability over historical times. These
ice-core records come from high mountain glaciers and the polar
regions, including small ice caps and the large ice sheets of Greenland
and Antarctica.
The Utility of the Revised Life Orientation Test to Measure Optimism among Hong Kong Chinese
Authors: Lai Julian C. L. , Cheung Him , Lee Wai‐man , Yu Helen
Published: July 2002

To examine the utility of the revised Life Orientation Test (LOT‐R) to measure optimism among Hong Kong Chinese, the psychometric properties of the revised and the original versions of the Life Orientation Test were compared. A total of 248 Hong Kong Chinese undergraduates were studied in the fall and 165 of these participants were tested again 5 months later. Results indicated that the LOT‐R is a reliable and valid measure of dispositional optimism among Hong Kong Chinese. Confirmatory factor analysis showed that the LOT‐R represents a one‐factor model of optimism better than does the original version. Despite its brevity, the LOT‐R is psychometrically sounder than the original sclae. These findings point to the feasibility of replacing the original with the revised scale in future research among Hong Kong Chinese. However, the utility of the revised test in cross‐cultural comparisons may still be limited by the absence of emic components. Further research on optimism in the Chinese people with the LOT‐R should pay more attention to the identification of emic dimensions.
A PolishMitteleuropa?: Upper Silesia's Conciliationists and the Prospect of German Victory
Authors: Bjork James
Published: July 2002

In the first days of August 1914, as enthusiastic crowds hailing the German declaration of war on Russia and France swarmed in front of the imperial residence in Berlin, Kaiser Wilhelm II famously declared that he no longer knew political parties, only Germans. The remark was intended to be rhetorically inclusive, of course, to signal the surmounting not only of party-political divisions but also of the empire's chronic class, confessional, and regional tensions. But for one of the empire's most marginalized groups of subjects—those millions who did not consider themselves of German descent and who spoke Polish rather than German as a native language—the Kaiser's invocation of a common German identity was more effective in underlining the limits rather than the promise of civic solidarity. Unlike the Habsburg Monarchy or (to a lesser extent) the Czarist Empire, where Polish nationalists could hope to reconcile commitment to their national cause with faithfulness to an imperial dynasty or even a diffuse sense of patriotism to a multinational state, the Hohenzollern monarchy had, over the previous half-century, become virtually synonymous with hostility to all things Polish. Upholding the Prussian monarchy, it seemed, was functionally inseparable from promoting a culturally homogenized German nation-state.
Systematic Reviews of Educational Research: Does the medical model fit?
Authors: Evans Jennifer , Benefield Pauline
Published: July 2002

Abstract There has been a recent increase in interest in the research review as a method of presenting cumulative data about the effects of educational policies and practices. This is part of a wider movement in ‘evidence‐informed policy‐making’ espoused by the current Government. In part, the interest as been sparked by the perceived success of the Cochrane Collaboration in medicine, which has set up a framework for conducting and verifying systematic reviews and meta‐analyses of random controlled trials of medical interventions. A pilot project to apply the methods of systematic review has been carried out at the National Foundation for Educational Research. The subject of the review was ‘Strategies to Support Pupils with Emotional and Behavioural Difficulties in Mainstream Primary Classrooms'. The article describes the process of the review, the adaptations of the ‘medical model’ to educational settings and discusses some of the implications of these for researchers and policy‐makers.
Where Have All the Women (and Men) Gone?
Authors: Johnson Penny , Kuttab Eileen
Published: July 2002

The authors ground their reflections on gender and the complex realities of the second Palestinian intifada against Israeli occupation in the political processes unleashed by the signing of the Israeli–Palestinian rule, noting that the profound inequalities between Israel and Palestine during the interim period produced inequalities among Palestinians. The apartheid logic of the Oslo period – made explicit in Israel's policies of separation, seige and confinement of the Palestinian population during the intifada and before it – is shown to shape the forms, sites and levels of resistance which are highly restricted by gender and age. In addition, the authors argue that the Palestinian Authority and leadership have solved the contradictions and crisis of Palestinian nationalism in this period through a form of rule that the authors term ‘authoritarian populism’, that tends to disallow democractic politics and participation. The seeming absence of women and civil society from the highly unequal and violent confrontations is contrasted with the first Palestinian intifada (1987–91), that occurred in a context of more than a decade of democratic activism and the growth of mass-based organizations, including the Palestinian women's movement. The authors explore three linked crises in gender roles emerging from the conditions of the second intifada: a crisis in masculinity, a crisis in paternity and a crisis in maternity.
Social dominance and prosocial and coercive strategies of resource control in preschoolers
Authors: Hawley Patricia H.
Published: July 2002

This study was designed to investigate the predictors of social dominance, the strategies children use to control resources (prosocial and coercive), and the associations between these strategies and measures of personality, social skills, and peer regard. A total of 30 preschoolers (ages 3–6) were rated by their teachers on social dominance. Based on these ratings, dominant children were paired with multiple subordinate children (i.e., block design; Kenny, 1990) and observed in a play situation designed to elicit resource control behaviour. As hypothesised, age and the surgency facet of extraversion predicted social dominance (but openness to experience did not). Furthermore, also as expected, both prosocial behaviour and coercive behaviour were related to resource control in the play situation. Last, both resource control strategies were associated with parent-rated social competence, but only coercive control was associated with positive peer regard (i.e., Likeability). Factors of personality (e.g. agreeableness, hostility) were not associated with either of the strategies. The utility of an evolutionary perspective to resource control and social competence is discussed.
International Adoption of Children: The Indian Scene
Authors: Apparao Hansa
Published: July 2002

The paper traces the history of international adoption of Indian children, against the background of the unique legal situation that governs the adoption matters in India. It describes the evolution of current policy and procedures on adoption, following the Indian Supreme Court ruling in 1984. A review of adoption in the preceding three decades highlights the dynamics of policies, practices, and trends in adoption of boys and girls in domestic and foreign adoptive homes. This gives an insight into the future prospects for adoption in India.
Intelligence and Learning Disabilities in 6- to 8-year-old Children Weighing under 1000 Grams at Birth
Authors: Kanazawa Tadahiro , Shimizu Satoshi , Kamada Jiro , Tanabe Hiroko , Itoigawa Naosuke
Published: July 2002

Intellectual ability and learning disabilities (LD) were assessed in a cohort of 33 extremely low-birthweight (1000 grams) children at 6-8 years of age with a psychometric test battery. The children were classified into the following three groups: a LD-suspected group of 9 boys (27.3%), a mentally delayed group of 3 boys and 3 girls (18.2%), and a typically developing group of 6 boys and 11 girls (51.5%). No correlation was found between birthweight and intelligence quotient (IQ) at 6-8 years of age. A negative correlation was found between IQ and gestational age (GA) at a nearly significant level. The mean verbal IQ for the 11 small for gestational age (SGA) children was significantly lower than that of the appropriate for gestational age (AGA) children. The LD-suspected group was characterised by lower scores on spatial relationships and rapid but inaccurate solving of the visuo-motor integration tasks on the Frostig test.