bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional cell surface expression of the anion transport domain of human red cell band 3 (AE1) in the yeast Saccharomyces cerevisiae.
Authors: Groves J D , Falson P , le Maire M , Tanner M J
Published: July 2002

We expressed the 52-kDa integral membrane domain (B3mem) of the human erythrocyte anion transporter (band 3; AE1) in a protease-deficient strain of the yeast Saccharomyces cerevisiae under the control of the inducible GAL10-CYC1 promoter. Immunoblots of total protein from transformed yeast cells confirmed that the B3mem polypeptide was overexpressed shortly after induction with galactose. Cell surface expression of the functional anion transporter was detected by using a simple transport assay to measure stilbene disulfonate-inhibitable chloride influx into intact yeast cells. The B3mem polypeptide was recycled and degraded by the cells with a half-life of approximately 1-3 hr, which led to a steady-state level of expression in exponentially growing cultures. Our data suggest that 5-10% of total B3mem is functionally active at the cell surface at any one time and that overexpression of this anion transport protein does not interfere with cell growth or survival. This is one of only a few reports of the functional expression of a plasma membrane transport protein in the plasma membrane of yeast cells and to our knowledge is the first report of red cell band 3-mediated anion transport at the plasma membrane of cDNA-transformed cells. The cell surface expression system we describe will provide a simple means for future study of the functional properties of band 3 by using site-directed mutagenesis.
Embryonic neuronal markers in tuberous sclerosis: Single-cell molecular pathology
Authors: Crino Peter B. , Trojanowski John Q. , Dichter Marc A. , Eberwine James
Published: July 2002

One hallmark of tuberous sclerosis (TSC) is the presence of highly epileptogenic dysplastic cerebral cortex (tubers) composed of abnormally shaped neurons and giant cells. Mutation of the TSC gene (TSC2) may disrupt differentiation and maturation of neuronal precursors, since theTSC2gene product tuberin is believed to regulate cellular proliferation. To test the hypothesis that cells in tubers may retain the molecular phenotype of embryonic or immature neurons, tubers from five TSC patients were probed with antibodies to proteins expressed in neuronal precursors (nestin, Ki-67, and proliferating cell nuclear antigen). Many dysmorphic neurons and giant cells in tubers were stained by these antibodies, while neurons in adjacent normal and control cortex were not labeled. To further characterize the molecular phenotype of cells in tubers, we developed a methodology in which poly(A)+mRNA was amplified from immunohistochemically labeled single cells in paraffin-embedded brain specimens. This approach enabled us to detect mRNAs encoding nestin, and other cytoskeletal elements, cell cycle markers, and synthetic enzymes present in individual nestin-stained cells by means of reverse Northern blotting. We conclude that the presence of immature phenotypic markers (mRNAs and proteins) within tubers suggests disruption of cell cycle regulation and neuronal maturation in TSC during cortical development. Characterization of multiple mRNAs within fixed, immunohistochemically labeled cells provides a powerful tool for studying gene expression and the molecular pathophysiology of many neurologic diseases.
Subcellular colocalization of the cellular and scrapie prion proteins in caveolae-like membranous domains
Authors: Vey Martin , Pilkuhn Susanne , Wille Holger , Nixon Randal , DeArmond Stephen J. , Smart Eric J. , Anderson Richard G. W. , Taraboulos Albert , Prusiner Stanley B.
Published: July 2002

Results of transgenetic studies argue that the scrapie isoform of
the prion protein (PrP
Sc
) interacts with the substrate
cellular PrP (PrP
C
) during conversion into nascent
PrP
Sc
. While PrP
Sc
appears to accumulate
primarily in lysosomes, caveolae-like domains (CLDs) have been
suggested to be the site where PrP
C
is converted into
PrP
Sc
. We report herein that CLDs isolated from
scrapie-infected neuroblastoma (ScN2a) cells contain PrP
C
and PrP
Sc
. After lysis of ScN2a cells in ice-cold Triton
X-100, both PrP isoforms and an N-terminally truncated form of
PrP
C
(PrP
C
-II) were found concentrated in
detergent-insoluble complexes resembling CLDs that were isolated by
flotation in sucrose gradients. Similar results were obtained when CLDs
were purified from plasma membranes by sonication and gradient
centrifugation; with this procedure no detergents are used, which
minimizes artifacts that might arise from redistribution of proteins
among subcellular fractions. The caveolar markers ganglioside GM1 and
H-ras were found concentrated in the CLD fractions. When plasma
membrane proteins were labeled with the impermeant reagent
sulfo-
N
-hydroxysuccinimide-biotin, both PrP
C
and PrP
Sc
were found biotinylated in CLD fractions.
Similar results on the colocalization of PrP
C
and
PrP
Sc
were obtained when CLDs were isolated from Syrian
hamster brains. Our findings demonstrate that both PrP
C
and
PrP
Sc
are present in CLDs and, thus, support the hypothesis
that the PrP
Sc
formation occurs within this subcellular
compartment.
Orally absorbed reactive glycation products (glycotoxins): An environmental risk factor in diabetic nephropathy
Authors: Koschinsky Theodore , He Ci-Jiang , Mitsuhashi Tomoko , Bucala Richard , Liu Cecilia , Buenting Christina , Heitmann Kirsten , Vlassara Helen
Published: July 2002

Endogenous advanced glycation endproducts (AGEs) include chemically crosslinking species (glycotoxins) that contribute to the vascular and renal complications of diabetes mellitus (DM). Renal excretion of the catabolic products of endogenous AGEs is impaired in patients with diabetic or nondiabetic kidney disease (KD). The aim of this study was to examine the oral absorption and renal clearance kinetics of food AGEs in DM with KD and whether circulating diet-derived AGEs contain active glycotoxins. Thirty-eight diabetics (DM) with or without KD and five healthy subjects (NL) received a single meal of egg white (56 g protein), cooked with (AGE-diet) or without fructose (100 g) (CL-diet). Serum and urine samples, collected for 48 hr, were monitored for AGE immunoreactivity by ELISA and for AGE-specific crosslinking reactivity, based on complex formation with
125
I-labeled fibronectin. The AGE-diet, but not the CL-diet, produced distinct elevations in serum AGE levels in direct proportion to amount ingested (
r
= 0.8,
P
< 0.05): the area under the curve for serum (≈10% of ingested AGE) correlated directly with severity of KD; renal excretion of dietary AGE, although normally incomplete (only ≈30% of amount absorbed), in DM it correlated inversely with degree of albuminuria, and directly with creatinine clearance (
r
= 0.8,
P
< 0.05), reduced to <5% in DM with renal failure. Post-AGE-meal serum exhibited increased AGE-crosslinking activity (two times above baseline serum AGE, three times above negative control), which was inhibited by aminoguanidine. In conclusion, (
i
) the renal excretion of orally absorbed AGEs is markedly suppressed in diabetic nephropathy patients, (
ii
) daily influx of dietary AGEs includes glycotoxins that may constitute an added chronic risk for renal-vascular injury in DM, and (
iii
) dietary restriction of AGE food intake may greatly reduce the burden of AGEs in diabetic patients and possibly improve prognosis.
Dependence of global temperatures on atmospheric CO2and solar irradiance
Authors: Thomson David J.
Published: July 2002

Changes in global average temperatures and of the seasonal cycle are strongly coupled to the concentration of atmospheric CO2. I estimate transfer functions from changes in atmospheric CO2and from changes in solar irradiance to hemispheric temperatures that have been corrected for the effects of precession. They show that changes from CO2over the last century are about three times larger than those from changes in solar irradiance. The increase in global average temperature during the last century is at least 20 times the SD of the residual temperature series left when the effects of CO2and changes in solar irradiance are subtracted.
The human A33 antigen is a transmembrane glycoprotein and a novel member of the immunoglobulin superfamily
Authors: Heath Joan K. , White Sara J. , Johnstone Cameron N. , Catimel Bruno , Simpson Richard J. , Moritz Robert L. , Tu Guo-Fen , Ji Hong , Whitehead Robert H. , Groenen Leo C. , Scott Andrew M. , Ritter Gerd , Cohen Leonard , Welt Sydney , Old Lloyd J. , Nice Edouard C. , Burgess Antony W.
Published: July 2002

The mAb A33 detects a membrane antigen that is expressed in normal human colonic and small bowel epithelium and >95% of human colon cancers. It is absent from most other human tissues and tumor types. The murine A33 mAb has been shown to target colon cancer in clinical trials, and the therapeutic potential of a humanized antibody is currently being evaluated. Using detergent extracts of the human colon carcinoma cell lines LIM1215 and SW1222, in which the antigen is highly expressed, the molecule was purified, yielding a 43-kDa protein. The N-terminal sequence was determined and further internal peptide sequence obtained following enzymatic cleavage. Degenerate primers were used in PCRs to produce a probe to screen a LIM1215 cDNA library, yielding clones that enabled us to deduce the complete amino acid sequence of the A33 antigen and express the protein. The available data bases have been searched and reveal no overall sequence similarities with known proteins. Based on a hydrophilicity plot, the A33 protein has three distinct structural domains: an extracellular region of 213 amino acids (which, by sequence alignment of conserved residues, contains two putative immunoglobulin-like domains), a single hydrophobic transmembrane domain, and a highly polar intracellular tail containing four consecutive cysteine residues. These data indicate that the A33 antigen is a novel cell surface receptor or cell adhesion molecule in the immunoglobulin superfamily.
The interaction of the general anesthetic etomidate with the γ-aminobutyric acid type A receptor is influenced by a single amino acid
Authors: Belelli Delia , Lambert Jeremy J. , Peters John A. , Wafford Keith , Whiting Paul J.
Published: July 2002

The γ-aminobutyric acid type A (GABA
A
) receptor is a transmitter-gated ion channel mediating the majority of fast inhibitory synaptic transmission within the brain. The receptor is a pentameric assembly of subunits drawn from multiple classes (α
1–6
, β
1–3
, γ
1–3
, δ
1
, and ɛ
1
). Positive allosteric modulation of GABA
A
receptor activity by general anesthetics represents one logical mechanism for central nervous system depression. The ability of the intravenous general anesthetic etomidate to modulate and activate GABA
A
receptors is uniquely dependent upon the β subunit subtype present within the receptor. Receptors containing β
2
- or β
3
-, but not β
1
subunits, are highly sensitive to the agent. Here, chimeric β
1
/β
2
subunits coexpressed in
Xenopus laevis
oocytes with human α
6
and γ
2
subunits identified a region distal to the extracellular N-terminal domain as a determinant of the selectivity of etomidate. The mutation of an amino acid (Asn-289) present within the channel domain of the β
3
subunit to Ser (the homologous residue in β
1
), strongly suppressed the GABA-modulatory and GABA-mimetic effects of etomidate. The replacement of the β
1
subunit Ser-290 by Asn produced the converse effect. When applied intracellularly to mouse L(tk−) cells stably expressing the α
6
β
3
γ
2
subunit combination, etomidate was inert. Hence, the effects of a clinically utilized general anesthetic upon a physiologically relevant target protein are dramatically influenced by a single amino acid. Together with the lack of effect of intracellular etomidate, the data argue against a unitary, lipid-based theory of anesthesia.
High-precision40Ar/39Ar geochronology and the advent of North America’s Late Cretaceous terrestrial fauna
Authors: Cifelli Richard L. , Kirkland James I. , Weil Anne , Deino Alan L. , Kowallis Bart J.
Published: July 2002

A densely sampled, diverse new fauna from the uppermost Cedar Mountain Formation, Utah, indicates that the basic pattern of faunal composition for the Late Cretaceous of North America was already established by the Albian-Cenomanian boundary. Multiple, concordant40Ar/39Ar determinations from a volcanic ash associated with the fauna have an average age of 98.39 ± 0.07 million years. The fauna of the Cedar Mountain Formation records the first global appearance of hadrosaurid dinosaurs, advanced lizard (e.g., Helodermatidae), and mammal (e.g., Marsupialia) groups, and the first North American appearance of other taxa such as tyrannosaurids, pachycephalosaurs, and snakes. Although the origin of many groups is unclear, combined biostratigraphic and phylogenetic evidence suggests an Old World, specifically Asian, origin for some of the taxa, an hypothesis that is consistent with existing evidence from tectonics and marine invertebrates. Large-bodied herbivores are mainly represented by low-level browsers, ornithopod dinosaurs, whose radiations have been hypothesized to be related to the initial diversification of angiosperm plants. Diversity at the largest body sizes (>106g) is low, in contrast to both preceding and succeeding faunas; sauropods, which underwent demise in the Northern hemisphere coincident with the radiation of angiosperms, apparently went temporarily unreplaced by other megaherbivores. Morphologic and taxonomic diversity among small, omnivorous mammals, multituberculates, is also low. A later apparent increase in diversity occurred during the Campanian, coincident with the appearance of major fruit types among angiosperms, suggesting the possibility of adaptive response to new resources.
Use of differential display analysis to assess the effect of human cytomegalovirus infection on the accumulation of cellular RNAs: Induction of interferon-responsive RNAs
Authors: Zhu Hua , Cong Jiang-Ping , Shenk Thomas
Published: July 2002

We used differential display analysis to identify mRNAs that accumulate to enhanced levels in human cytomegalovirus-infected cells as compared with mock-infected cells. RNAs were compared at 8 hr after infection of primary human fibroblasts. Fifty-seven partial cDNA clones were isolated, representing about 26 differentially expressed mRNAs. Eleven of the mRNAs were virus-coded, and 15 were of cellular origin. Six of the partial cDNA sequences have not been reported previously. All of the cellular mRNAs identified in the screen are induced by interferon α. The induction in virus-infected cells, however, does not involve the action of interferon or other small signaling molecules. Neutralizing antibodies that block virus infection also block the induction. These RNAs accumulate after infection with virus that has been inactivated by treatment with UV light, indicating that the inducer is present in virions. We conclude that human cytomegalovirus induces interferon-responsive mRNAs.
The γ
1
34.5 protein of herpes simplex virus 1 complexes with protein phosphatase 1α to dephosphorylate the α subunit of the eukaryotic translation initiation factor 2 and preclude the shutoff of protein synthesis by double-stranded RNA-activated protein kinase
Authors: He Bin , Gross Martin , Roizman Bernard
Published: July 2002

In human cells infected with herpes simplex virus 1 the double-stranded RNA-dependent protein kinase (PKR) is activated but phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF-2) and total shutoff of protein synthesis is observed only in cells infected with γ
1
z34.5
−
mutants. The carboxyl-terminal 64 aa of γ
1
34.5 protein are homologous to the corresponding domain of MyD116, the murine growth arrest and DNA damage gene 34 (GADD34) protein and the two domains are functionally interchangeable in infected cells. This report shows that (
i
) the carboxyl terminus of MyD116 interacts with protein phosphatase 1α in yeast, and both MyD116 and γ
1
34.5 interact with protein phosphatase 1α
in vitro
; (
ii
) protein synthesis in infected cells is strongly inhibited by okadaic acid, a phosphatase 1 inhibitor; and (
iii
) the α subunit in purified eIF-2 phosphorylated
in vitro
is specifically dephosphorylated by S10 fractions of wild-type infected cells at a rate 3000 times that of mock-infected cells, whereas the eIF-2α-P phosphatase activity of γ
1
34.5
−
virus infected cells is lower than that of mock-infected cells. The eIF-2α-P phosphatase activities are sensitive to inhibitor 2. In contrast to eIF-2α-P phosphatase activity, extracts of mock-infected cells exhibit a 2-fold higher phosphatase activity on [
32
P]phosphorylase than extracts of infected cells. These results indicate that in infected cells, γ
1
34.5 interacts with and redirects phosphatase to dephosphorylate eIF-2α to enable continued protein synthesis despite the presence of activated PKR. The GADD34 protein may have a similar function in eukaryotic cells. The proposed mechanism for maintenance of protein synthesis in the face of double-stranded RNA accumulation is different from that described for viruses examined to date.
From phosphatases to vanadium peroxidases: A similar architecture of the active site
Authors: Hemrika Wieger , Renirie Rokus , Dekker Henk L. , Barnett Phil , Wever Ron
Published: July 2002

We show here that the amino acid residues contributing to the active sites of the vanadate containing haloperoxidases are conserved within three families of acid phosphatases; this suggests that the active sites of these enzymes are very similar. This is confirmed by activity measurements showing that apochloroperoxidase exhibits phosphatase activity. These observations not only reveal interesting evolutionary relationships between these groups of enzymes but may also have important implications for the research on acid phosphatases, especially glucose-6-phosphatase—the enzyme affected in von Gierke disease—of which the predicted membrane topology may have to be reconsidered.
Directionality principles in thermodynamics and evolution
Authors: Demetrius Lloyd
Published: July 2002

Directionality in populations of replicating organisms can be parametrized in terms of a statistical concept: evolutionary entropy. This parameter, a measure of the variability in the age of reproducing individuals in a population, is isometric with the macroscopic variable body size. Evolutionary trends in entropy due to mutation and natural selection fall into patterns modulated by ecological and demographic constraints, which are delineated as follows: (i) density-dependent conditions (a unidirectional increase in evolutionary entropy), and (ii) density-independent conditions, (a) slow exponential growth (an increase in entropy); (b) rapid exponential growth, low degree of iteroparity (a decrease in entropy); and (c) rapid exponential growth, high degree of iteroparity (random, nondirectional change in entropy). Directionality in aggregates of inanimate matter can be parametrized in terms of the statistical concept, thermodynamic entropy, a measure of disorder. Directional trends in entropy in aggregates of matter fall into patterns determined by the nature of the adiabatic constraints, which are characterized as follows: (i) irreversible processes (an increase in thermodynamic entropy) and (ii) reversible processes (a constant value for entropy). This article analyzes the relation between the concepts that underlie the directionality principles in evolutionary biology and physical systems. For models of cellular populations, an analytic relation is derived between generation time, the average length of the cell cycle, and temperature. This correspondence between generation time, an evolutionary parameter, and temperature, a thermodynamic variable, is exploited to show that the increase in evolutionary entropy that characterizes population processes under density-dependent conditions represents a nonequilibrium analogue of the second law of thermodynamics.
Defense activation and enhanced pathogen tolerance induced by H
2
O
2
in transgenic tobacco
Authors: Chamnongpol Sangpen , Willekens Hilde , Moeder Wolfgang , Langebartels Christian , Sandermann Heinrich , Van Montagu Marc , Inzé Dirk , Van Camp Wim
Published: July 2002

Transgenic tobacco deficient in the H
2
O
2
-removing enzyme catalase (Cat1AS) was used as an inducible and noninvasive system to study the role of H
2
O
2
as an activator of pathogenesis-related (PR) proteins in plants. Excess H
2
O
2
in Cat1AS plants was generated by simply increasing light intensities. Sustained exposure of Cat1AS plants to excess H
2
O
2
provoked tissue damage, stimulated salicylic acid and ethylene production, and induced the expression of acidic and basic PR proteins with a timing and magnitude similar to the hypersensitive response against pathogens. Salicylic acid production was biphasic, and the first peak of salicylic acid as well as the peak of ethylene occurred within the first hours of high light, which is long before the development of tissue necrosis. Under these conditions, accumulation of acidic PR proteins was also seen in upper leaves that were not exposed to high light, indicating systemic induction of expression. Short exposure of Cat1AS plants to excess H
2
O
2
did not cause damage, induced local expression of acidic and basic PR proteins, and enhanced pathogen tolerance. However, the timing and magnitude of PR protein induction was in this case more similar to that in upper uninfected leaves than to that in hypersensitive-response leaves of pathogen-infected plants. Together, these data demonstrate that sublethal levels of H
2
O
2
activate expression of acidic and basic PR proteins and lead to enhanced pathogen tolerance. However, rapid and strong activation of PR protein expression, as seen during the hypersensitive response, occurs only when excess H
2
O
2
is accompanied by leaf necrosis.
A sensory neuron-specific, proton-gated ion channel
Authors: Chen Chih-Cheng , England Steven , Akopian Armen N. , Wood John N.
Published: July 2002

Proton-gated channels expressed by sensory neurons are of particular interest because low pH causes pain. Two proton-gated channels, acid-sensing ionic channel (ASIC) and dorsal root ASIC (DRASIC), that are members of the amiloride-sensitive ENaC/Degenerin family are known to be expressed by sensory neurons. Here, we describe the cloning and characterization of an ASIC splice variant, ASIC-β, which contains a unique N-terminal 172 aa, as well as unique 5′ and 3′ untranslated sequences. ASIC-β, unlike ASIC and DRASIC, is found only in a subset of small and large diameter sensory neurons and is absent from sympathetic neurons or the central nervous system. The patterns of expression of ASIC and ASIC-β transcripts in rat dorsal root ganglion neurons are distinct. When expressed in COS-7 cells, ASIC-β forms a functional channel with electrophysiological properties distinct from ASIC and DRASIC. The pH dependency and sensitivity to amiloride of ASIC-β is similar to that described for ASIC, but unlike ASIC, the channel is not permeable to calcium, nor are ASIC-β-mediated currents inhibited by extracellular calcium. The unique distribution of ASIC-β suggests that it may play a specialized role in sensory neuron function.
Acetylation and modulation of erythroid Krüppel-like factor (EKLF) activity by interaction with histone acetyltransferases
Authors: Zhang Wenjun , Bieker James J.
Published: July 2002

Erythroid Krüppel-like factor (EKLF) is a red cell-specific transcriptional activator that is crucial for consolidating the switch to high levels of adult β-globin expression during erythroid ontogeny. EKLF is required for integrity of the chromatin structure at the β-like globin locus, and it interacts with a positive-acting factor
in vivo
. We find that EKLF is an acetylated transcription factor, and that it interacts
in vivo
with CBP, p300, and P/CAF. However, its interactions with these histone acetyltransferases are not equivalent, as CBP and p300, but not P/CAF, utilize EKLF as a substrate for
in vitro
acetylation within its trans-activation region. The functional effects of these interactions are that CBP and p300, but not P/CAF, enhance EKLF’s transcriptional activation of the β-globin promoter in erythroid cells. These results establish EKLF as a tissue-specific transcription factor that undergoes post-translational acetylation and suggest a mechanism by which EKLF is able to alter chromatin structure and induce β-globin expression within the β-like globin cluster.
Glial reduction in the subgenual prefrontal cortex in mood disorders
Authors: Öngür Dost , Drevets Wayne C. , Price Joseph L.
Published: July 2002

Mood disorders are among the most common neuropsychiatric illnesses, yet little is known about their neurobiology. Recent neuroimaging studies have found that the volume of the subgenual part of Brodmann’s area 24 (sg24) is reduced in familial forms of major depressive disorder (MDD) and bipolar disorder (BD). In this histological study, we used unbiased stereological techniques to examine the cellular composition of area sg24 in two different sets of brains. There was no change in the number or size of neurons in area sg24 in mood disorders. In contrast, the numbers of glia were reduced markedly in both MDD and BD. The reduction in glial number was most prominent in subgroups of subjects with familial MDD (24%,
P
= 0.01) or BD (41%,
P
= 0.01). The glial reduction in subjects without a clear family history was lower in magnitude and not statistically significant. Consistent with neuroimaging findings, cortical volume was reduced in area sg24 in subjects with familial mood disorders. Schizophrenic brains studied as psychiatric controls had normal neuronal and glial numbers and cortical volume. Glial and neuronal numbers also were counted in area 3b of the somatosensory cortex in the same group of brains and were normal in all psychiatric groups. Glia affect several processes, including regulation of extracellular potassium, glucose storage and metabolism, and glutamate uptake, all of which are crucial for normal neuronal activity. We thus have identified a biological marker associated with familial mood disorders that may provide important clues regarding the pathogenesis of these common psychiatric conditions.
Chemokines regulate hippocampal neuronal signaling and gp120 neurotoxicity
Authors: Meucci Olimpia , Fatatis Alessandro , Simen Arthur A. , Bushell Trevor J. , Gray Patrick W. , Miller Richard J.
Published: July 2002

The HIV-1 envelope protein gp120 induces apoptosis in hippocampal neurons. Because chemokine receptors act as cellular receptors for HIV-1, we examined rat hippocampal neurons for the presence of functional chemokine receptors. Fura-2-based Ca imaging showed that numerous chemokines, including SDF-1α, RANTES, and fractalkine, affect neuronal Ca signaling, suggesting that hippocampal neurons possess a wide variety of chemokine receptors. Chemokines also blocked the frequency of spontaneous glutamatergic excitatory postsynaptic currents recorded from these neurons and reduced voltage-dependent Ca currents in the same neurons. Reverse transcription–PCR demonstrated the expression of CCR1, CCR4, CCR5, CCR9/10, CXCR2, CXCR4, and CX
3
CR1, as well as the chemokine fractalkine in these neurons. Both fractalkine and macrophage-derived chemokine (MDC) produced a time-dependent activation of extracellular response kinases (ERK)-1/2, whereas no activation of c-JUN NH
2
-terminal protein kinase (JNK)/stress-activated protein kinase, or p38 was evident. Furthermore, these two chemokines, as well as SDF-1α, activated the Ca- and cAMP-dependent transcription factor CREB. Several chemokines were able also to block gp120-induced apoptosis of hippocampal neurons, both in the presence and absence of the glial feeder layer. These data suggest that chemokine receptors may directly mediate gp120 neurotoxicity.
From patterns to processes: Phase and density dependencies in the Canadian lynx cycle
Authors: Stenseth Nils C. , Falck Wilhelm , Chan Kung-Sik , Bjørnstad Ottar N. , O’Donoghue Mark , Tong Howell , Boonstra Rudy , Boutin Stan , Krebs Charles J. , Yoccoz Nigel G.
Published: July 2002

Across the boreal forest of North America, lynx populations undergo 10-year cycles. Analysis of 21 time series from 1821 to the present demonstrates that these fluctuations are generated by nonlinear processes with regulatory delays. Trophic interactions between lynx and hares cause delayed density-dependent regulation of lynx population growth. The nonlinearity, in contrast, appears to arise from phase dependencies in hunting success by lynx through the cycle. Using a combined approach of empirical, statistical, and mathematical modeling, we highlight how shifts in trophic interactions between the lynx and the hare generate the nonlinear process primarily by shifting functional response curves during the increase and the decrease phases.
Cerebral organization for language in deaf and hearing subjects: Biological constraints and effects of experience
Authors: Neville Helen J. , Bavelier Daphne , Corina David , Rauschecker Josef , Karni Avi , Lalwani Anil , Braun Allen , Clark Vince , Jezzard Peter , Turner Robert
Published: July 2002

Cerebral organization during sentence processing in English and in American Sign Language (ASL) was characterized by employing functional magnetic resonance imaging (fMRI) at 4 T. Effects of deafness, age of language acquisition, and bilingualism were assessed by comparing results from (i) normally hearing, monolingual, native speakers of English, (ii) congenitally, genetically deaf, native signers of ASL who learned English late and through the visual modality, and (iii) normally hearing bilinguals who were native signers of ASL and speakers of English. All groups, hearing and deaf, processing their native language, English or ASL, displayed strong and repeated activation within classical language areas of the left hemisphere. Deaf subjects reading English did not display activation in these regions. These results suggest that the early acquisition of a natural language is important in the expression of the strong bias for these areas to mediate language, independently of the form of the language. In addition, native signers, hearing and deaf, displayed extensive activation of homologous areas within the right hemisphere, indicating that the specific processing requirements of the language also in part determine the organization of the language systems of the brain.
Irregular arrays and randomization
Authors: Singer Burton H. , Pincus Steve
Published: July 2002

Although they lie at the conceptual core of a wide range of scientific questions, the notions of irregular or “random” arrangement and the process of randomization itself have never been unambiguously defined. Algorithmic implementation of these concepts requires a combinatorial, rather than a probability-theoretic, formulation. We introduce vector versions of approximate entropy to quantify the degrees of irregularity of planar (and higher dimensional) arrangements. Selection rules, applied to the elements of irregular permutations, define randomization in strictly combinatorial terms. These concepts are developed in the context of Latin square arrangements and valid randomization of them. Conflicts and tradeoffs between the objectives of irregular arrangements and valid randomization are highlighted. Extensions to broad classes of designs, and a diverse range of scientific applications are indicated, including lattice-based models in physics and signal detection in seismology and physiology.
Engineering analysis of biological variables: An example of blood pressure over 1 day
Authors: Huang Wei , Shen Zheng , Huang Norden E. , Fung Yuan Cheng
Published: July 2002

Almost all variables in biology are nonstationarily stochastic. For these variables, the conventional tools leave us a feeling that some valuable information is thrown away and that a complex phenomenon is presented imprecisely. Here, we apply recent advances initially made in the study of ocean waves to study the blood pressure waves in the lung. We note first that, in a long wave train, the handling of the local mean is of predominant importance. It is shown that a signal can be described by a sum of a series of intrinsic mode functions, each of which has zero local mean at all times. The process of deriving this series is called the “empirical mode decomposition method.” Conventionally, Fourier analysis represents the data by sine and cosine functions, but no instantaneous frequency can be defined. In the new way, the data are represented by intrinsic mode functions, to which Hilbert transform can be used. Titchmarsh [Titchmarsh, E. C. (1948)Introduction to the Theory of Fourier Integrals(Oxford Univ. Press, Oxford)] has shown that a signal and i times its Hilbert transform together define a complex variable. From that complex variable, the instantaneous frequency, instantaneous amplitude, Hilbert spectrum, and marginal Hilbert spectrum have been defined. In addition, the Gumbel extreme-value statistics are applied. We present all of these features of the blood pressure records here for the reader to see how they look. In the future, we have to learn how these features change with disease or interventions.
Calcineurin controls inositol 1,4,5-trisphosphate type 1 receptor expression in neurons
Authors: Genazzani Armando A. , Carafoli Ernesto , Guerini Danilo
Published: July 2002

In the central nervous system, release of Ca2+from intracellular stores contributes to numerous functions, including neurotransmitter release and long-term potentiation and depression. We have investigated the developmental profile and the regulation of inositol 1,4,5-trisphosphate receptor (IP3R) and ryanodine receptor (RyR) in primary cultures of cerebellar granule cells. The expression of both receptor types increases during development. Whereas the expression of type 1 IP3R appears to be regulated by Ca2+influx through L type channels orN-methyl-d-aspartate (NMDA) receptors, RyR levels increase independently of Ca2+. The main target of Ca2+-influx-regulating IP3R expression is the Ca2+calmodulin-dependent protein phosphatase calcineurin, because pharmacological blockade of this protein abolishes IP3R expression. Although calcineurin has been shown to regulate the phosphorylation state of the IP3R, the effect described here is at the transcriptional level because IP3R mRNA changes in parallel with protein levels. Thus, calcineurin plays a dual role in IP3R-mediated Ca2+signaling: it regulates IP3R function by dephosphorylation in the short-term time scale and IP3R expression over more extended periods.
A mutation in the human ortholog of theSaccharomyces cerevisiae ALG6gene causes carbohydrate-deficient glycoprotein syndrome type-Ic
Authors: Imbach Timo , Burda Patricie , Kuhnert Peter , Wevers Ron A. , Aebi Markus , Berger Eric G. , Hennet Thierry
Published: July 2002

Carbohydrate-deficient glycoprotein syndrome (CDGS) represents a class of genetic diseases characterized by abnormal N-linked glycosylation. CDGS patients show a large number of glycoprotein abnormalities resulting in dysmorphy, encephalopathy, and other organ disorders. The majority of CDGSs described to date are related to an impaired biosynthesis of dolichyl pyrophosphate-linked Glc3Man9GlcNAc2in the endoplasmic reticulum. Recently, we identified in four related patients a novel type of CDGS characterized by an accumulation of dolichyl pyrophosphate-linked Man9GlcNAc2. Elaborating on the analogy of this finding with the phenotype ofalg5andalg6 Saccharomyces cerevisiaestrains, we have cloned and analyzed the human orthologs to theALG5dolichyl phosphate glucosyltransferase andALG6dolichyl pyrophosphate Man9GlcNAc2α1,3-glucosyltransferase in four novel CDGS patients. AlthoughALG5was not altered in the patients, a C→T transition was detected inALG6cDNA of all four CDGS patients. The mutation cosegregated with the disease in a Mendelian recessive manner. Expression of the humanALG5andALG6cDNA could partially complement the respectiveS. cerevisiae alg5andalg6deficiency. By contrast, the mutantALG6cDNA of CDGS patients failed to revert the hypoglycosylation observed inalg6yeasts, thereby proving a functional relationship between the alanine to valine substitution introduced by the C→T transition and the CDGS phenotype. The mutation in theALG6α1,3-glucosyltransferase gene defines an additional type of CDGS, which we propose to refer to as CDGS type-Ic.
Spray aiming in the bombardier beetle: Photographic evidence
Authors: Eisner Thomas , Aneshansley Daniel J.
Published: July 2002

Bombardier beetles, when physically assaulted, eject a hot quinonoid spray from the tip of the abdomen. Photographic evidence is presented demonstrating that the African bombardier beetle,Stenaptinus insignis, can aim its spray in virtually any direction. It can target its individual legs, and even the individual segments of its legs. Moreover, in aiming at a leg, it takes into account the postural orientation of that leg. The beetle is able even to target sites on its back. It is postulated that the ability to aim helps the beetle mainly in defense against ants.
Experimental hemochromatosis due to MHC class I HFE deficiency: Immune status and iron metabolism
Authors: Bahram Seiamak , Gilfillan Susan , Kühn Lukas C. , Moret Rémy , Schulze Johannes B. , Lebeau Annette , Schümann Klaus
Published: July 2002

The puzzling linkage between genetic hemochromatosis and histocompatibility loci became even more so when the gene involved,HFE, was identified. Indeed, within the well defined, mainly peptide-binding, MHC class I family of molecules,HFEseems to perform an unusual yet essential function. As yet, our understanding ofHFEfunction in iron homeostasis is only partial; an even more open question is its possible role in the immune system. To advance on both of these avenues, we report the deletion ofHFEα1 and α2 putative ligand binding domainsin vivo.HFE-deficient animals were analyzed for a comprehensive set of metabolic and immune parameters. Faithfully mimicking human hemochromatosis, mice homozygous for this deletion develop iron overload, characterized by a higher plasma iron content and a raised transferrin saturation as well as an elevated hepatic iron load. The primary defect could, indeed, be traced to an augmented duodenal iron absorption. In parallel, measurement of the gut mucosal iron content as well as iron regulatory proteins allows a more informed evaluation of various hypotheses regarding the precise role ofHFEin iron homeostasis. Finally, an extensive phenotyping of primary and secondary lymphoid organs including the gut provides no compelling evidence for an obvious immune-linked function forHFE.
Mouse model of Sanfilippo syndrome type B produced by targeted disruption of the gene encoding α-N-acetylglucosaminidase
Authors: Li Hong Hua , Yu Wei-Hong , Rozengurt Nora , Zhao Hui-Zhi , Lyons Karen M. , Anagnostaras Stephan , Fanselow Michael S. , Suzuki Kunihiko , Vanier Marie T. , Neufeld Elizabeth F.
Published: July 2002

The Sanfilippo syndrome type B is an autosomal recessive disorder caused by mutation in the gene (NAGLU) encoding α-N-acetylglucosaminidase, a lysosomal enzyme required for the stepwise degradation of heparan sulfate. The most serious manifestations are profound mental retardation, intractable behavior problems, and death in the second decade. To generate a model for studies of pathophysiology and of potential therapy, we disrupted exon 6 ofNaglu, the homologous mouse gene.Naglu−/−mice were healthy and fertile while young and could survive for 8–12 mo. They were totally deficient in α-N-acetylglucosaminidase and had massive accumulation of heparan sulfate in liver and kidney as well as secondary changes in activity of several other lysosomal enzymes in liver and brain and elevation of gangliosides GM2and GM3in brain. Vacuolation was seen in many cells, including macrophages, epithelial cells, and neurons, and became more prominent with age. Although most vacuoles contained finely granular material characteristic of glycosaminoglycan accumulation, large pleiomorphic inclusions were seen in some neurons and pericytes in the brain. Abnormal hypoactive behavior was manifested by 4.5-mo-oldNaglu−/−mice in an open field test; the hyperactivity that is characteristic of affected children was not observed even in younger mice. In a Pavlovian fear conditioning test, the 4.5-mo-old mutant mice showed normal response to context, indicating intact hippocampal-dependent learning, but reduced response to a conditioning tone, perhaps attributable to hearing impairment. The phenotype of the α-N-acetylglucosaminidase-deficient mice is sufficiently similar to that of patients with the Sanfilippo syndrome type B to make these mice a good model for study of pathophysiology and for development of therapy.
Prevention of lymphocyte cell death in sepsis improves survival in mice
Authors: Hotchkiss R. S. , Tinsley K. W. , Swanson P. E. , Chang K. C. , Cobb J. P. , Buchman T. G. , Korsmeyer S. J. , Karl I. E.
Published: July 2002

Sepsis induces extensive lymphocyte apoptosis, a process which may be beneficial to host survival by down-regulating the inflammatory response or, alternatively, harmful by impairing host defenses. To determine the beneficial vs. adverse effects of lymphocyte apoptosis in sepsis, we blocked lymphocyte apoptosis either byN-benzyloxycarbonyl-Val-Ala-Asp(O-methyl) fluoromethyl ketone (z-VAD), a broad-spectrum caspase inhibitor, or by use of Bcl-2 Ig transgenic mice that selectively overexpress the antiapoptotic protein Bcl-2 in a lymphoid pattern. Bothz-VAD and Bcl-2 prevented lymphocyte apoptosis and resulted in a marked improvement in survival.z-VAD did not decrease lymphocyte tumor necrosis factor-α production. Considered together, these two studies employing different methods of blocking lymphocyte apoptosis provide compelling evidence that immunodepression resulting from the loss of lymphocytes is a central pathogenic event in sepsis, and they challenge the current paradigm that regards sepsis as a disorder resulting from an uncontrolled inflammatory response. Caspase inhibitors may represent a treatment strategy in this highly lethal disorder.
Habitat, world geographic range, and embryonic development of hosts explain the prevalence of avian hematozoa at small spatial and phylogenetic scales
Authors: Tella José L. , Blanco Guillermo , Forero Manuela G. , Gajón Álvaro , Donázar José A. , Hiraldo Fernando
Published: July 2002

The factors explaining interspecific differences in prevalences of blood parasites in birds are poorly known. We simultaneously assessed 20 social, ecological, life history, and sampling-related variables that could influence hemoparasite prevalences among diurnal birds of prey in Spain. Our results show that multiple factors are responsible for the studied host–parasite association. We confirmed for the first time that prevalence is inversely correlated to the embryonic development period, and thus probably to immune performance, even among closely related birds. Macrohabitat features related to vector availability are also important, prevalences being higher in species breeding in forested habitats. Finally, prevalence is positively correlated with the host’s world geographic range. We hypothesize that larger geographic ranges offered more opportunities for host-vector-hemoparasite associations to become established. The results from our multivariate analyses differ from those obtained through univariate ones, showing that all potential factors should be assessed jointly when testing any ecological or evolutionary hypothesis dealing with parasites.
Dopamine β-hydroxylase deficiency impairs cellular immunity
Authors: Alaniz Robert C. , Thomas Steven A. , Perez-Melgosa Mercedes , Mueller Kai , Farr Andrew G. , Palmiter Richard D. , Wilson Christopher B.
Published: July 2002

Norepinephrine, released from sympathetic neurons, and epinephrine, released from the adrenal medulla, participate in a number of physiological processes including those that facilitate adaptation to stressful conditions. The thymus, spleen, and lymph nodes are richly innervated by the sympathetic nervous system, and catecholamines are thought to modulate the immune response. However, the importance of this modulatory rolein vivoremains uncertain. We addressed this question genetically by using mice that lack dopamine β-hydroxylase (dbh−/−mice).dbh−/−mice cannot produce norepinephrine or epinephrine, but produce dopamine instead. When housed in specific pathogen-free conditions,dbh−/−mice had normal numbers of blood leukocytes, and normal T and B cell development andin vitrofunction. However, when challengedin vivoby infection with the intracellular pathogensListeria monocytogenesorMycobacterium tuberculosis,dbh−/−mice were more susceptible to infection, exhibited extreme thymic involution, and had impaired T cell function, including Th1 cytokine production. When immunized with trinitrophenyl-keyhole limpet hemocyanin,dbh−/−mice produced less Th1 cytokine-dependent-IgG2a antitrinitrophenyl antibody. These results indicate that physiological catecholamine production is not required for normal development of the immune system, but plays an important role in the modulation of T cell-mediated immunity to infection and immunization.
Regulation of fatty acid homeostasis in cells: Novel role of leptin
Authors: Unger Roger H. , Zhou Yan-Ting , Orci Lelio
Published: July 2002

It is proposed that an important function of leptin is to confine the storage of triglycerides (TG) to the adipocytes, while limiting TG storage in nonadipocytes, thus protecting them from lipotoxicity. The fact that TG content in nonadipocytes normally remains within a narrow range, while that of adipocytes varies enormously with food intake, is consistent with a system of TG homeostasis in normal nonadipocytes. The facts that when leptin receptors are dysfunctional, TG content in nonadipocytes such as islets can increase 100-fold, and that constitutively expressed ectopic hyperleptinemia depletes TG, suggest that leptin controls the homeostatic system for intracellular TG. The fact that the function and viability of nonadipocytes is compromised when their TG content rises above or falls below the normal range suggests that normal homeostasis of their intracellular TG is critical for optimal function and to prevent lipoapoptosis. Thus far, lipotoxic diabetes of
fa/fa
Zucker diabetic fatty rats is the only proven lipodegenerative disease, but the possibility of lipotoxic disease of skeletal and/or cardiac muscle may require investigation, as does the possible influence of the intracellular TG content on autoimmune and neoplastic processes.