bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional characterization of serum‐ and growth factor‐induced phenotypic changes in intact bovine tracheal smooth muscle
Authors: Gosens Reinoud , Meurs Herman , Bromhaar Mechteld M Grootte , McKay Sue , Nelemans S Adriaan , Zaagsma Johan
Published: October 2002

The present study aims to investigate whether phenotypic changes, reported to occur in cultured isolated airway smooth muscle (ASM) cells, are of relevance to intact ASM. Moreover, we aimed to gain insight into the signalling pathways involved.

Culturing of bovine tracheal smooth muscle (BTSM) strips for up to 8 days in the presence of 10% foetal bovine serum caused a time‐dependent (t1/2=2.8 days) decrease in maximal contraction (Emax) to methacholine compared to serum‐deprived controls (Emax=74±4% at day 8). A reduced Emax was also found using insulin‐like growth factor‐1 (30 ng ml−1) and platelet‐derived growth factor (30 ng ml−1), but not using epidermal growth factor (10 ng ml−1) (Emax=83±3, 67±8, 100±4%, respectively). Similar serum and growth factor‐induced changes in Emax were found for KCl‐induced contraction (65±9, 80±7, 64±11% and 107±2%, respectively).

Strong correlations were found between the growth factor‐induced reductions in Emax and their proliferative responses, assessed by [3H]‐thymidine‐incorporation, in BTSM cells. (r=0.97, P=0.002 for methacholine and r=0.93, P=0.007 for KCl).

The PDGF‐induced reduction in Emax was inhibited completely by combined treatment with either PD 98059 (30 μM) or LY 294002 (10 μM).

These results indicate that serum and growth factors may cause a functional shift towards a less contractile phenotype in intact BTSM, which is associated with their proliferative response and dependent on signalling pathways involving the mitogen‐activated protein kinase pathway and the phosphatidylinositol‐3‐kinase pathway.

British Journal of Pharmacology (2002) 137, 459–466. doi:10.1038/sj.bjp.0704889
Relaxation to bradykinin in bovine pulmonary supernumerary arteries can be mediated by both a nitric oxide‐dependent and ‐independent mechanism
Authors: Tracey A , Bunton D , Irvine J , MacDonald A , Shaw A M
Published: October 2002

The aim of the present study was to determine the relative contribution of prostanoids, nitric oxide and K+ channels in the bradykinin‐induced relaxation of bovine pulmonary supernumerary arteries.

In endothelium‐intact, but not denuded rings, bradykinin produced a concentration‐dependent relaxation (pEC50, 9.6±0.1), which was unaffected by the cyclo‐oxygenase inhibitor indomethacin. The nitric oxide scavenger hydroxocobalamin (200 μM, pEC50, 8.5±0.2) and the nitric oxide synthase inhibitor L‐NAME (100 μM, pEC50, 8.9±0.1) and the combination of L‐NAME and hydroxocobalamin (pEC50, 8.1±0.2) produced rightward shifts in the bradykinin concentration response curve.

The guanylyl cyclase inhibitor ODQ (10 μM, pEC50, 9.6±0.4) did not affect the response to bradykinin.

Elevating the extracellular [K+] to 30 mM did not affect the response to bradykinin but abolished the response when ODQ or L‐NAME was present.

The K+ channel blocker apamin (100 nM), combined with charybdotoxin (100 nM), produced a small reduction in the maximum response to bradykinin but they abolished the response to bradykinin when ODQ, L‐NAME or hydroxocobalamin were present. Apamin (100 nM) combined with iberiotoxin (100 nM) also reduced the response to bradykinin in the presence of hydroxocobalamin or L‐NAME.

The concentration response curve for sodium nitroprusside‐induced relaxation was abolished by ODQ (10 μM) and shifted to the right by apamin and charybdotoxin.

These studies suggest that in bovine pulmonary supernumerary arteries bradykinin can stimulate the formation of nitric oxide and activate an EDHF‐like mechanism and that either of these pathways alone can mediate the bradykinin‐induced relaxation. In addition nitric oxide, acting through guanylyl cyclase, can activate an apamin/charbydotoxin‐sensitive K+ channel in this tissue.

British Journal of Pharmacology (2002) 137, 538–544. doi:10.1038/sj.bjp.0704890
T‐channel‐like pharmacological properties of highvoltage‐activated, nifedipine‐insensitive Ca2+ currents inthe rat terminal mesenteric artery
Authors: Morita Hiromitsu , Shi Juan , Ito Yushi , Inoue Ryuji
Published: October 2002

Pharmacological properties of nifedipine‐insensitive, high voltage‐activated Ca2+ channels in rat mesenteric terminal arteries (NICCs) were investigated and compared with those of α1E and α1G heterologously expressed in BHK and HEK293 cells respectively, using the patch clamp technique.

With 10 mM Ba2+ as the charge carrier, rat NICCs (unitary conductance: 11.5 pS with 110 mM Ba2+) are almost identical to those previously identified in a similar region of guinea‐pig, such as in current‐voltage relationship, voltage dependence of activation and inactivation, and divalent cation permeability. However, these properties are considerably different when compared with α1E and α1G.

SNX‐482(200 nM and sFTX3.3 (1 μM), in addition to ω‐conotoxin GVIA (1 μM) and ω‐agatoxin IVA (100 nM), were totally ineffective for rat NICC currents, but significantly suppressed α1E (by 82% at 200 nM; IC50=11.1 nM) and α1G (by 20% at 1 μM) channel currents, respectively. A non‐specific T‐type Ca2+ channel blocker nimodipine (10 μM) differentially suppressed these three currents (by 40, 3 and 85% for rat NICC, α1E and α1G currents, respectively).

Mibefradil, the widely used T‐type channel blocker, almost equally inhibited rat NICC and α1G currents in a voltage‐dependent fashion with similar IC50 values (3.5 and 0.3 μM and 2.4 and 0.14 μM at −100 and −60 mV, respectively). Furthermore, other organic T‐type channel blockers such as phenytoin, ethosuximide, an arylpiperidine derivative SUN N5030 (IC50=0.32 μM at −60 mV for α1G) also exhibited comparable inhibitory efficacies for NICC currents (inhibited by 22% at 100 μM; IC50=27.8 mM; IC50=0.53 μM, respectively).

These results suggest that despite distinctive biophysical properties, the rat NICCs have indistinguishable pharmacological sensitivities to many organic blockers compared with T‐type Ca2+ channels.

British Journal of Pharmacology (2002) 137, 467–476. doi:10.1038/sj.bjp.0704892
Fructose‐1,6‐diphosphate attenuates prostaglandin E2 production and cyclo‐oxygenase‐2 expression in UVB‐irradiated HaCaT keratinocytes
Authors: Ahn Soo Mi , Yoon Hyoung‐Young , Lee Byung Gon , Park Kyoung Chan , Chung Jin Ho , Moon Chang‐Hyun , Lee Soo Hwan
Published: October 2002

Fructose‐1,6‐diphosphate (FDP), a glycolytic metabolite, is reported to ameliorate inflammation and inhibit the nitric oxide production in murine macrophages stimulated with endotoxin. It is also reported that FDP has cytoprotective effects against hypoxia or ischaemia/reperfusion injury in brain and heart. However, underlying mechanisms of its various biological activities are not completely understood.

In this study, we examined the effects of FDP on UVB‐induced prostaglandin production in HaCaT keratinocytes.

Ultraviolet B (UVB, 280–320 nm) irradiation (30 mJ cm−2) increased prostaglandin E2(PGE2) production, which was significantly decreased by FDP in a concentration dependent manner. NS‐398, a cyclo‐oxygenase‐2 (COX‐2) selective inhibitor completely inhibited UVB‐induced PGE2 production showing that COX‐2 activity is responsible for the increase in PGE2 production under our experimental conditions.

UVB irradiation increased total COX activity and COX‐2 mRNA in HaCaT keratinocytes, which were significantly blocked by FDP in a concentration dependent manner.

N‐acetylcysteine (NAC) significantly attenuated UVB‐induced PGE2 production, COX activity and COX‐2 mRNA expression indicating oxidative components might contribute to these events.

FDP reduced UVB‐induced increase in cellular reactive oxygen species (ROS) level although it did not show direct radical scavenging effect in the experiment using 1,1‐diphenyl‐2picrylhydrazil (DPPH). FDP preserved the cellular antioxidant capacity including catalase activity and GSH content after irradiation.

Our data obtained hitherto suggest that FDP may have a protective role in UVB‐injured keratinocyte by attenuating PGE2 production and COX‐2 expression, which are possibly through blocking intracellular ROS accumulation.

British Journal of Pharmacology (2002) 137, 497–503. doi:10.1038/sj.bjp.0704896
ATP‐induced endothelium‐independent enhancement of lymphatic vasomotion in guinea‐pig mesentery involves P2X and P2Y receptors
Authors: Zhao Jun , van Helden Dirk F
Published: October 2002

The present study has investigated mechanisms underlying ATP‐induced endothelium‐independent enhancement of vasomotion in guinea‐pig mesenteric lymphatic vessels.

Lymphatic vasomotion, vessel tone and smooth muscle [Ca2+]i showed similar ATP concentration‐response curves.

ATP, at 0.1 mM, caused a biphasic increase in tonic [Ca2+]i and superimposed vasomotion‐associated Ca2+ transients. All ATP‐induced [Ca2+]i changes were abolished by incubating the smooth muscle with suramin (0.1 mM).

α,β‐MeATP (0.1 mM) and UTP (0.1 mM) caused similar changes in [Ca2+]i but the responses to these agonists were smaller than to ATP.

The actions of α,β‐MeATP (0.1 mM) were inhibited by suramin (0.1 mM) and PPADS (30 μM) but not by reactive blue 2 (30 μM).

In the presence of α,β‐MeATP (0.1 mM), the increases in tonic [Ca2+]i and vasomotion‐associated Ca2+ transients induced by ATP (0.1 mM) were inhibited by U73122 (5 μM), CPA (20 μM) and heparin, whereas U73343 (5 μM) and pre‐treatment with PTx (100 ng ml−1) had no significant effects.

Depletion of the intracellular stores with CPA (20 μM) caused an increase in [Ca2+]i, which was not blocked by desensitization of P2X receptors with α,β‐MeATP.

The data indicate that ATP, at relatively high concentrations increases lymphatic smooth muscle [Ca2+]i and vasomotion through activation of P2X1 and P2Y2 purinoceptors present on lymphatic smooth muscle. The increase in [Ca2+]i is likely to result from Ca2+ release from inositol‐1,4,5‐trisphosphate‐sensitive stores as well as Ca2+ influx through store‐operated channels and P2X‐gated channels.

British Journal of Pharmacology (2002) 137, 477–487. doi:10.1038/sj.bjp.0704899
Anandamide is a partial agonist at native vanilloid receptors in acutely isolated mouse trigeminal sensory neurons
Authors: Roberts Louise A , Christie MacDonald J , Connor Mark
Published: October 2002

The endogenous fatty acid anandamide (AEA) is a partial agonist at cannabinoid CB1 receptors and has been reported to be a full agonist at the recombinant vanilloid receptor, VR1.

Whole cell voltage clamp techniques were used to examine the efficacy of AEA and related analogues methanandamide and N‐(4‐hydroxyphenyl)‐arachidonylamide (AM404) at native VR1 receptors in acutely isolated mouse trigeminal neurons.

Superfusion of the VR1 agonist capsaicin onto small trigeminal neurons voltage clamped at +40 mV produced outward currents in most cells, with a pEC50 of 6.3±0.1 (maximum currents at 10–30 μM).

AEA produced outward currents with a pEC50 of 5.6±0.1. Maximal AEA currents (30–100 μM) were 38±2% of the capsaicin maximum. AEA currents were blocked by the VR1 antagonist capsazepine (30 μM), but unaffected by the CB1 antagonist SR141716A (1 μM).

Methanandamide and AM404 were less potent than AEA at activating VR1. Methanandamide (100 μM) produced currents 37±6% of the capsaicin maximum, the highest concentration of AM404 tested (100 μM) produced currents that were 55±9% of the capsaicin maximum.

Capsazepine abolished the currents produced by AM404 (100 μM) and strongly attenuated (>70%) those produced by methanandamide (100 μM).

Co‐superfusion of AEA (30 μM, methanandamide (100 μM) or AM404 (100 μM) with capsaicin (3 μM) resulted in a significant reduction of the capsaicin current.

These data indicate that AEA, methanandamide and AM404 activate native VR1 receptors, but that all three compounds are partial agonists when compared with capsaicin.

British Journal of Pharmacology (2002) 137, 421–428. doi:10.1038/sj.bjp.0704904
Nanocrystal targeting
in vivo
Authors: Åkerman Maria E. , Chan Warren C. W. , Laakkonen Pirjo , Bhatia Sangeeta N. , Ruoslahti Erkki
Published: October 2002

Inorganic nanostructures that interface with biological systems have recently attracted widespread interest in biology and medicine. Nanoparticles are thought to have potential as novel intravascular probes for both diagnostic (e.g., imaging) and therapeutic purposes (e.g., drug delivery). Critical issues for successful nanoparticle delivery include the ability to target specific tissues and cell types and escape from the biological particulate filter known as the reticuloendothelial system. We set out to explore the feasibility of
in vivo
targeting by using semiconductor quantum dots (qdots). Qdots are small (<10 nm) inorganic nanocrystals that possess unique luminescent properties; their fluorescence emission is stable and tuned by varying the particle size or composition. We show that ZnS-capped CdSe qdots coated with a lung-targeting peptide accumulate in the lungs of mice after i.v. injection, whereas two other peptides specifically direct qdots to blood vessels or lymphatic vessels in tumors. We also show that adding polyethylene glycol to the qdot coating prevents nonselective accumulation of qdots in reticuloendothelial tissues. These results encourage the construction of more complex nanostructures with capabilities such as disease sensing and drug delivery.
Microarray analysis reveals a major direct role of DNA copy number alteration in the transcriptional program of human breast tumors
Authors: Pollack Jonathan R. , Sørlie Therese , Perou Charles M. , Rees Christian A. , Jeffrey Stefanie S. , Lonning Per E. , Tibshirani Robert , Botstein David , Børresen-Dale Anne-Lise , Brown Patrick O.
Published: October 2002

Genomic DNA copy number alterations are key genetic events in the development and progression of human cancers. Here we report a genome-wide microarray comparative genomic hybridization (array CGH) analysis of DNA copy number variation in a series of primary human breast tumors. We have profiled DNA copy number alteration across 6,691 mapped human genes, in 44 predominantly advanced, primary breast tumors and 10 breast cancer cell lines. While the overall patterns of DNA amplification and deletion corroborate previous cytogenetic studies, the high-resolution (gene-by-gene) mapping of amplicon boundaries and the quantitative analysis of amplicon shape provide significant improvement in the localization of candidate oncogenes. Parallel microarray measurements of mRNA levels reveal the remarkable degree to which variation in gene copy number contributes to variation in gene expression in tumor cells. Specifically, we find that 62% of highly amplified genes show moderately or highly elevated expression, that DNA copy number influences gene expression across a wide range of DNA copy number alterations (deletion, low-, mid- and high-level amplification), that on average, a 2-fold change in DNA copy number is associated with a corresponding 1.5-fold change in mRNA levels, and that overall, at least 12% of all the variation in gene expression among the breast tumors is directly attributable to underlying variation in gene copy number. These findings provide evidence that widespread DNA copy number alteration can lead directly to global deregulation of gene expression, which may contribute to the development or progression of cancer.
Linking individuals with ecosystems: Experimentally identifying the relevant organizational scale for predicting trophic abundances
Authors: Ovadia Ofer , Schmitz Oswald J.
Published: October 2002

Ecosystems are complex owing to the fact that emergent properties like trophic structure and productivity depend on details related to lower-scale interactions among individuals. A key challenge is identifying how much individual-level detail is needed to predict patterns at the ecosystem level. We tested for the effect of individual herbivore body size on trophic interactions and consequent abundances of plant and herbivore trophic levels in a New England meadow ecosystem. Body size is an important determinant of vulnerability to predation and thus should influence the way individuals tradeoff time spent foraging against time spent avoiding contact with predators. Such tradeoffs can then influence the degree of damage herbivores inflict on their plant resources. We experimentally assigned field-caught grasshoppers to three distinct body size treatment groups (small, normal, and large) and crossed them with two spider predator treatments (spider present and absent) in a fully replicated design. We observed size-dependent differences in grasshopper survival and development. Moreover, predators caused grasshoppers to inflict greater damage to herbs and lesser damage to grasses relative to treatments without predators. However, there were no size-dependent differences in net damage level on grasses and herbs in either predator or no predator treatments owing to size-dependent compensation in grasshopper foraging effort. We thus conclude that in this ecosystem the foraging-predation risk tradeoff displayed by typical or average-sized herbivore is a sufficient amount of individual-level detail needed to explain ecosystem patterns.
Structural rearrangements in single ion channels detected optically in living cells
Authors: Sonnleitner Alois , Mannuzzu Lidia M. , Terakawa Susumu , Isacoff Ehud Y.
Published: October 2002

Total internal reflection fluorescence microscopy was used to detect single fluorescently labeled voltage-gated Shaker K
+
channels in the plasma membrane of living cells. Tetramethylrhodamine (TMR) attached to specific amino acid positions in the voltage-sensing S4 segment changed fluorescence intensity in response to the voltage-driven protein motions of the channel. The voltage dependence of the fluorescence of single TMRs was similar to that seen in macroscopic epi-illumination microscopy, but the exclusion of nonchannel fluorescence revealed that the dimming of TMR upon voltage sensor rearrangement was much larger than previously thought, and is due to an extreme, ≈20-fold suppression of the elementary fluorescence. The total internal reflection voltage-clamp method reveals protein motions that do not directly open or close the ion channel and which have therefore not been detected before at the single-channel level. The method should be applicable to a wide assortment of membrane-associated proteins and should make it possible to relate the structural rearrangements of single proteins to simultaneously measured physiological cell-signaling events.
C-reactive protein binds to both oxidized LDL and apoptotic cells through recognition of a common ligand: Phosphorylcholine of oxidized phospholipids
Authors: Chang Mi-Kyung , Binder Christoph J. , Torzewski Michael , Witztum Joseph L.
Published: October 2002

C-reactive protein (CRP) is an acute-phase protein that binds specifically to phosphorylcholine (PC) as a component of microbial capsular polysaccharide and participates in the innate immune response against microorganisms. CRP elevation also is a major risk factor for cardiovascular disease. We previously demonstrated that EO6, an antioxidized LDL autoantibody, was a T15 clono-specific anti-PC antibody and specifically binds to PC on oxidized phosphatidylcholine (PtC) but not on native PtC. Similarly, EO6 binds apoptotic cells but not viable cells. In addition, such oxidized phospholipids are recognized by macrophage scavenger receptors, implying that these innate immune responses participate in the clearance because of their proinflammatory properties. We now report that CRP binds to oxidized LDL (OxLDL) and oxidized PtC (OxPtC), but does not bind to native, nonoxidized LDL nor to nonoxidized PtC, and its binding is mediated through the recognition of a PC moiety. Reciprocally, CRP binds to PC, which can be competed for by OxLDL and OxPtC but not by native LDL, nonoxidized PtC, or by oxidized phospholipids without the PC headgroup. CRP also binds to apoptotic cells, and this binding is competed for by OxLDL, OxPtC, and PC. These data suggest that CRP binds OxLDL and apoptotic cells by recognition of a PC moiety that becomes accessible as a result of oxidation of PtC molecule. We propose that, analogous to EO6 and scavenger receptors, CRP is a part of the innate immune response to oxidized PC-bearing phospholipids within OxLDL and on the plasma membranes of apoptotic cells.
Heritable endogenous gene regulation in plants with designed polydactyl zinc finger transcription factors
Authors: Guan Xuen , Stege Justin , Kim Myoung , Dahmani Zina , Fan Nancy , Heifetz Peter , Barbas Carlos F. , Briggs Steven P.
Published: October 2002

Zinc finger transcription factors (TFs
ZF
) were designed and applied to transgene and endogenous gene regulation in stably transformed plants. The target of the TFs
ZF
is the
Arabidopsis
gene
APETALA3
(
AP3
), which encodes a transcription factor that determines floral organ identity. A zinc finger protein (ZFP) was designed to specifically bind to a region upstream of
AP3. AP3
transcription was induced by transformation of leaf protoplasts with a transformation vector that expressed a TF
ZF
consisting of the ZFP fused to the tetrameric repeat of herpes simplex VP16's minimal activation domain. Histochemical staining of β-glucuronidase (GUS) activity in transgenic AP3∷GUS reporter plants expressing GUS under control of the
AP3
promoter was increased dramatically in petals when the
AP3
-specific TF
ZF
activator was cointroduced. TF
ZF
-amplified GUS expression signals were also evident in sepal tissues of these double-transgenic plants. Floral phenotype changes indicative of endogenous
AP3
factor coactivation were also observed. The same
AP3
-specific ZFP
AP3
was also fused to a human transcriptional repression domain, the mSIN3 interaction domain, and introduced into either AP3∷GUS-expressing plants or wild-type
Arabidopsis
plants. Dramatic repression of endogenous
AP3
expression in floral tissue resulted when a constitutive promoter was used to drive the expression of this TF
ZF
. These plants were also sterile. When a floral tissue-specific promoter from
APETALA1
(
AP1
) gene was used, floral phenotype changes were also observed, but in contrast the plants were fertile. Our results demonstrate that artificial transcriptional factors based on synthetic zinc finger proteins are capable of stable and specific regulation of endogenous genes through multiple generations in multicellular organisms.
β-Globin mRNA decay in erythroid cells: UG site-preferred endonucleolytic cleavage that is augmented by a premature termination codon
Authors: Stevens Audrey , Wang Yang , Bremer Kirsten , Zhang Jing , Hoepfner Robert , Antoniou Michael , Schoenberg Daniel R. , Maquat Lynne E.
Published: October 2002

Previous work showed that human β-globin mRNAs harboring a premature termination codon are degraded in the erythroid tissues of mice to products that lack sequences from the mRNA 5′ end but contain a 5′ cap-like structure. Whether these decay products are the consequence of endonucleolytic or 5′-to-3′ exonucleolytic activity is unclear. We report that this β-globin mRNA decay pathway is recapitulated in cultured mouse erythroleukemia (MEL) cells and targets nonsense-free mRNA to a lesser extent than nonsense-containing mRNA. S1 nuclease mapping and primer extension demonstrated that 70–80% of decay product 5′ ends contain a UG dinucleotide. Detection of upstream counterparts of these decay products indicates that they are generated by endonucleolytic activity. Both crude and partially purified polysome extracts prepared from MEL cells contain an endonucleolytic activity that generates decay products comparable to those observed
in vivo
. These data suggest that an endonuclease with preference for UG dinucleotides is involved in the degradation of nonsense-containing and, to a lesser extent, nonsense-free human β-globin mRNAs in mouse erythroid cells.
Zmpste24
deficiency in mice causes spontaneous bone fractures, muscle weakness, and a prelamin A processing defect
Authors: Bergo Martin O. , Gavino Bryant , Ross Jed , Schmidt Walter K. , Hong Christine , Kendall Lonnie V. , Mohr Andreas , Meta Margarita , Genant Harry , Jiang Yebin , Wisner Erik R. , van Bruggen Nicholas , Carano Richard A. D. , Michaelis Susan , Griffey Stephen M. , Young Stephen G.
Published: October 2002

Zmpste24 is an integral membrane metalloproteinase of the endoplasmic reticulum. Biochemical studies of tissues from
Zmpste24
-deficient mice (
Zmpste24
−/−
) have indicated a role for Zmpste24 in the processing of
CAAX
-type prenylated proteins. Here, we report the pathologic consequences of
Zmpste24
deficiency in mice.
Zmpste24
−/−
mice gain weight slowly, appear malnourished, and exhibit progressive hair loss. The most striking pathologic phenotype is multiple spontaneous bone fractures—akin to those occurring in mouse models of osteogenesis imperfecta. Cortical and trabecular bone volumes are significantly reduced in
Zmpste24
−/−
mice.
Zmpste24
−/−
mice also manifested muscle weakness in the lower and upper extremities, resembling mice lacking the farnesylated
CAAX
protein prelamin A. Prelamin A processing was defective both in fibroblasts lacking
Zmpste24
and in fibroblasts lacking the
CAAX
carboxyl methyltransferase Icmt but was normal in fibroblasts lacking the
CAAX
endoprotease Rce1. Muscle weakness in
Zmpste24
−/−
mice can be reasonably ascribed to defective processing of prelamin A, but the brittle bone phenotype suggests a broader role for Zmpste24 in mammalian biology.
Lipoxin A4and aspirin-triggered 15-epi-lipoxin A4inhibit peroxynitrite formation, NF-κB and AP-1 activation, and IL-8 gene expression in human leukocytes
Authors: József Levente , Zouki Christine , Petasis Nicos A. , Serhan Charles N. , Filep János G.
Published: October 2002

Lipoxin A4(LXA4) and aspirin-triggered 15-epi-LXA4(ATL) are emerging as endogenous braking signals for neutrophil-mediated tissue injury. Recent studies indicate that peroxynitrite (ONOO−) may function as an intracellular signal for the production of IL-8, a potent proinflammatory cytokine in human leukocytes. In this study, we evaluated the impact of the metabolically stable analogues of LXA4/ATL on lipopolysaccharide (LPS)-induced ONOO−formation and ONOO−-mediated IL-8 gene expression in human leukocytes. At nanomolar concentrations, LXA4analogues markedly reduced LPS-stimulated superoxide formation, evoked increases in intracellular diamino-fluorescein fluorescence (an indicator of NO formation), and consequently reduced ONOO−formation in isolated neutrophils, as well as in neutrophils, monocytes, and lymphocytes, in whole blood. LXA4/ATL analogues attenuated nuclear accumulation of activator protein-1 and nuclear factor-κB in both polymorphonuclear and mononuclear leukocytes and inhibited IL-8 mRNA expression and IL-8 release by 50–65% in response to LPS. The LXA4inhibitory responses were concentration dependent and were not shared by 15-deoxy-LXA4. None of the LXA4analogues studied affected neutrophil survival, nor reversed the apoptosis delaying action of LPS in neutrophils. In addition, LXA4analogues had no significant effect on exogenous ONOO−-induced IL-8 gene and protein expression. These findings suggest that by attenuating ONOO−formation, LXA4and ATL can oppose ONOO−signaling in leukocytes and provide a rationale for using stable synthetic analogues as antiinflammatory compoundsin vivo.
Timing-dependent limbic-motor synaptic integration in the nucleus accumbens
Authors: Goto Yukiori , O'Donnell Patricio
Published: October 2002

The nucleus accumbens is a brain region in which limbic and motor inputs converge. How these information modalities shape accumbens output is not clearly understood. Here, we report that synaptic inputs from the prefrontal cortex and limbic structures interact differently depending on their timing. Coincident inputs may result in enhancing information flow through the nucleus accumbens. Responses to asynchronous inputs are affected by their relative order of arrival, with limbic inputs allowing subsequent prefrontal responses, and prefrontal inputs dampening limbic responses. These mechanisms allow for both coincidence detection and input selection in this integrative brain region.
Galectin-1 is a stromal cell ligand of the pre-B cell receptor (BCR) implicated in synapse formation between pre-B and stromal cells and in pre-BCR triggering
Authors: Gauthier Laurent , Rossi Benjamin , Roux Florence , Termine Elise , Schiff Claudine
Published: October 2002

Although preB cell-receptor (pre-BCR) formation and cell-surface expression is essential for B cell development, pre-BCR generation of signal transduction remains elusive. Here, we report that recombinant pre-BCRs and the surrogate light chain bind specifically to the bone marrow stromal cell galectin-1 (GAL1), an S-type lectin. The surrogate light chain/GAL1 association is a direct protein–protein interaction (Ka= 2 × 106M−1), and the NH2extra loop of λ-like is the major binding element. Pre-BCR binding to stromal cells depends upon GAL1 anchoring to glycosylated counter-receptors, and these complexes completely relocalize to form a synapse at the contact zone between preB and stromal cells. This immune developmental synapse is accompanied by the initiation of intracellular tyrosine kinase activity and signal transduction from the pre-BCR.
Genetic diversity and selection in the maize starch pathway
Authors: Whitt Sherry R. , Wilson Larissa M. , Tenaillon Maud I. , Gaut Brandon S. , Buckler Edward S.
Published: October 2002

Maize is both phenotypically and genetically diverse. Sequence studies generally confirm the extensive genetic variability in modern maize is consistent with a lack of selection. For more than 6,000 years, Native Americans and modern breeders have exploited the tremendous genetic diversity of maize (
Zea mays
ssp.
mays
) to create the highest yielding grain crop in the world. Nonetheless, some loci have relatively low levels of genetic variation, particularly loci that have been the target of artificial selection, like
c1
and
tb1
. However, there is limited information on how selection may affect an agronomically important pathway for any crop. These pathways may retain the signature of artificial selection and may lack genetic variation in contrast to the rest of the genome. To evaluate the impact of selection across an agronomically important pathway, we surveyed nucleotide diversity at six major genes involved in starch metabolism and found unusually low genetic diversity and strong evidence of selection. Low diversity in these critical genes suggests that a paradigm shift may be required for future maize breeding. Rather than relying solely on the diversity within maize or on transgenics, future maize breeding would perhaps benefit from the incorporation of alleles from maize's wild relatives.
The roles of the external, middle, and inner ears in determining the bandwidth of hearing
Authors: Ruggero Mario A. , Temchin Andrei N.
Published: October 2002

The view seems to prevail that the frequency range of hearing is determined by the properties of the outer and middle ears. We argue that this view is an oversimplification, in part because the reactive component of cochlear input impedance, which affects the low-frequency sensitivity of the cochlea, is neglected. Further, we use comparisons of audiograms and transfer functions for stapes (or columella) velocity or pressure in scala vestibuli near the stapes footplate to show that the middle ear by itself is not responsible for limiting high-frequency hearing in the few species for which such comparisons are possible. Finally, we propose that the tonotopic organization of the cochlea plays a crucial role in setting the frequency limits of cochlear sensitivity and hence in determining the bandwidth of hearing.
Flow visualization and unsteady aerodynamics in the flight of the hawkmoth,Manduca sexta
Authors: Willmott Alexander P. , Ellington Charles P. , Thomas Adrian L. R.
Published: October 2002

The aerodynamic mechanisms employed durng the flight of the hawkmoth,Manduca sexta, have been investigated through smoke visualization studies with tethered moths. Details of the flow around the wings and of the overall wake structure were recorded as stereophotographs and high–speed video sequences. The changes in flow which accompanied increases in flight speed from 0.4 to 5.7 m s−1were analysed. The wake consists of an alternating series of horizontal and vertical vortex rings which are generated by successive down– and upstrokes, respectively. The downstroke produces significantly more lift than the upstroke due to a leading–edge vortex which is stabilized by a radia flow moving out towards the wingtip. The leading–edge vortex grew in size with increasing forward flight velocity. Such a phenomenon is proposed as a likely mechanism for lift enhancement in many insect groups. During supination, vorticity is shed from the leading edge as postulated in the ‘flex’ mechanism. This vorticity would enhance upstroke lift if it was recaptured diring subsequent translation, but it is not. Instead, the vorticity is left behind and the upstroke circulation builds up slowly. A small jet provides additional thrust as the trailing edges approach at the end of the upstroke. The stereophotographs also suggest that the bound circulation may not be reversed between half strokes at the fastest flight speeds.
Analysis and fitting of an
SIR
model with host response to infection load for a plant disease
Authors: Gilligan Christopher A. , Gubbins Simon , Simons Sarah A.
Published: October 2002

We reformulate a model for botanical epidemics into an
SIR
form for susceptible (
S
), infected (
I
) and removed (
R
) plant organs, in order to examine the effects of different models for the effect of host responses to the load of infection on the production of susceptible tissue. The new formulation also allows for a decline in host susceptibility with age. The model is analysed and tested for the stem canker disease of potatoes, caused by the soil–borne fungus,
Rhizoctonia solani
. Using a combination of model fitting to field data and analysis of model behaviour, we show that a function for host response to the amount (load) of parasite infection is critical in the description of the temporal dynamics of susceptible and infected stems in epidemics of
R. solani
. Several different types of host response to infection are compared including two that allow for stimulation of the plant to produce more susceptible tissue at low levels of disease and inhibition at higher levels. We show that when the force of infection decays with time, due to increasing resistance of the host, the equilibrium density of susceptible stems depends on the parameters and initial conditions. The models differ in sensitivity to small changes in disease transmission with some showing marked qualitative changes leading to a flush of susceptible stems at low levels of disease transmission. We conclude that there is no evidence to reject an
SIR
model with a simpler linear term for the effect of infection load on the production of healthy tissue, even though biological considerations suggest greater complexity in the relationship between disease and growth. We show that reduction in initial inoculum density, and hence in the force of infection, is effective in controlling disase when the simple model applies.
Heart mass and the maximum cardiac output of birds and mammals: implications for estimating the maximum aerobic power input of flying animals
Authors: Bishop Charles M.
Published: October 2002

Empirical studies of cardiovascular variables suggest that relative heart muscle mass (relativeMh) is a good indicator of the degree of adaptive specialization for prolonged locomotor activities, for both birds and mammals. Reasonable predictions for the maximum oxygen consumption of birds during flight can be obtained by assuming that avian heart muscle has the same maximum physiological and biomechanical performance as that of terrestrial mammals. Thus, data onMhcan be used to provide quantitative estimates for the maximum aerobic power input (aerobicPi, max) available to animals during intense levels of locomotor activity. The maximum cardiac output of birds and mammals is calculated to scale with respect toMh(g) as 213Mh0.88±0.04(ml min−1), while aerobicPi,maxis estimated to scale approximately as 11Mh0.88±0.09(W). In general, estimated inter–species aerobicPi,max, based onMhfor all bird species (excluding hummingbirds), is calculated to scale with respect to body mass (Mbin kg) as 81Mb0.82±0.11(W). Comparison of family means forMhindicate that there is considerable diversity in aerobic capacity among birds and mammals, for example, among the medium to large species of birds the Tinamidae have the smallest relativeMh(0.25 %) while the Otidae have unusually large relativeMh(1.6 %). Hummingbirds have extremely large relativeMh(2.28 %), but exhibit significant sexual dimorphism in their scaling ofMhand flight muscle mass, so that when considering hummingbird flight performance it may be useful to control for sexual differences in morphology. The estimated scaling of aerobicPi,max(based onMhandMbin g) for male and female hummingbirds is 0.51Mb0.83 ±0.07and 0.44Mb0.85± 0.11(W), respectively. Locomotory muscles are dynamic structures and it might be anticipated that where additional energetic ‘costs’ occur seasonally (e.g. due to migratory fattening or the development of large secondary sexual characteristics) then the relevant cardiac and locomotor musculature might also be regulated seasonally. This is an important consideration, both due to the intrinsic interest of studying muscular adaptation to changes in energy demand, but also as a confounding variable in the practical use of heart rate to estimate the energetics of animals. Haemoglobin concentration (or haematocrit) may also be a confounding variable. Thus, it is concluded that data on the cardiovascular and flight muscle morphology of animals provides essential information regarding the behavioural, ecological and physiological significance of the flight performance of animals.
The physical basis of reflective communication between fish, with special reference to the horse mackerel,Trachurus trachurus
Authors: Rowe D. M. , Denton E. J.
Published: October 2002

Some properties of reflecting structures in the external surfaces ofTrachurus trachurusand some other fish are described. These are related to the hypothesis that such structures are useful, especially to schooling fish, for communicating information on relative positions, orientations, and movements between neighbours. In addition to the silvery layers on the main body surfaces, there are:(a)highly silvered patches on the tail, the pectoral fins and the jaws which, in the sea, will become much brighter or darker with any movement such as a tailbeat or mouth opening which changes their orientations in the ambient lightfield, and(b)structures such as the dorsal lateral line which, in the sea, will only appear bright from certain directions. To us, the colours of the ventral flanks change from bright red to blue with direction orientations and have special reflectivity curves close to those predicted by A.F. Huxley for interference reflectors which are ‘ideal’ λ/4 stacks of guanine crystals and cytoplasm. The wavebands best reflected by such platelets move to shorter wavelengths with increasing angle of incidence, also in accord with these equations. At normal incidence, the outer layer of platelets reflects maximally for far–red light which penetrates only a short distance in the sea. Such layers can, however, be useful at oblique angles where they reflect maximally in the yellow and blue. The inner layer of reflectors reflects very strongly in the blue at normal incidence, but reflects in the ultra–violet at oblique angles. Some theoretical studies are made on the ways in which the patterns of reflectivity by single and superposed layers of λ/4 stacks could signal a fish's movements or its position relative to its neighbours.
Population dynamics of botanical epidemics involving primary and secondary infection
Authors: Gilligan Christopher A. , Kleczkowski Adam
Published: October 2002

In this paper we study the dynamical properties of models for botanical epidemics, especially for soil–borne fungal infection. The models develop several new concepts, involving dual sources of infection, host and inoculum dynamics. Epidemics are modelled with respect to the infection status of whole plants and plant organs (theGmodel) or to lesion density and size (theSWmodel). The infection can originate in two sources, either from the initial inoculum (primary infection) or by a direct transmission between plant tissue (secondary infection). The first term corresponds to the transmission through the free–living stages of macroparasites or an external source of infection in certain medical models, whereas the second term is equivalent to direct transmission between the hosts in microparasitic infections. The models allow for dynamics of host growth and inoculum decay. We show that the two models for root and lesion dynamics can be derived as special cases of a single generic model. Analytical and numerical methods are used to analyse the behaviour of the models for static, unlimited (exponential) and asymptotically limited host growth with and without secondary infection, and with and without decay of initial inoculum. The models are shown to exhibit a range of epidemic behaviour within single seasons that extends from simple monotonic increase with saturation of the host population, through temporary plateaux as the system switches from primary to secondary infection, to effective elimination of the pathogen by the host outgrowing the fungal infection. For certain conditions, the equilibrium values are shown to depend on initial conditions. These results have important consequences for the control of plant disease. They can be applied beyond soil–borne plant pathogens to mycorrhizal fungi and aerial pathogens while the principles of primary and secondary infection with host and inoculum dynamics may be used to link classical models for both microparasitic and macroparasitic infections.
Signalling among relatives. I. Is costly signalling
too
costly?
Authors: Bergstrom Carl T. , Lachmann Michael
Published: October 2002

Zahavi's handicap principle,originally proposed as an explanation for sexual selection ofelaborate male traits, suggests that a sufficient cost to dishonest signals can outweigh the rewards of deception and allow individuals to communicate honestly. Maynard Smith (1991) and Johnstone and Grafen (1992) introduce the Sir Philip Sidney game in order to extend the handicap principle to interactions among related individuals, and to demonstrate that stable costly signalling systems can exist among relatives.

In this paper we demonstrate that despite the benefits associated with honest information transfer, the costs incurred in a stable costly signalling system may leave all participants worse off than they would be in a system with no signalling at all. In both the discrete and continuous forms of the Sir Philip Sidney game, there exist conditions under which costly signalling among relatives, while stable, is so costly that it is disadvantageous compared with no signalling at all. We determine the factors which dictate signal cost and signal benefit in a generalized version of this game, and explain how signal cost can exceed signal value. Such results raise concerns about theevolutionary pathways which could have led to the existence of signalling equilibria in nature. The paper stresses the importance of comparing signalling equilibria with other possible strategies, beforedrawing conclusions regarding the optimality of signalling.
Preface for a Discussion on Near–infrared spectroscopy and imaging of living systems
Authors: Reynolds E. O. R.
Published: October 2002

Preface for a Discussion on Near–infrared spectroscopy and imaging of living systems. A Discussion held at the Royal Society on 23rd and 24th October 1996. Organized and edited by B. Chance, C. E. Cooper, D. T. Delpy and E. O. R. Reynolds.
Non–invasive measurements of breast tissue optical properties using frequency–domain photon migration
Authors: Tromberg Bruce J. , Coquoz Olivier , Fishkin Joshua B. , Pham Tuan , Anderson Eric R. , Butler John , Cahn Mitchell , Gross Jeffrey D. , Venugopalan Vasan , Pham David
Published: October 2002

A multiwavelength, high bandwidth (1 GHz) frequency–domain photon migration (FDPM) instrument has been developed for quantitative, non–invasive measurements of tissue optical and physiological properties. The instrument produces 300 kHz to 1 GHz photon density waves (PDWs) in optically turbid media using a network analyser, an avalanche photodiode detector and four amplitude–modulated diode lasers (674 nm, 811 nm, 849 nm and 956 nm). The frequency–dependence of PDW phase and amplitude is measured and compared to analytically derived model functions in order to calculate absorption,μa, and reduced scattering,μ′s, parameters. The wavelength–dependence of absorption is used to determine tissue haemoglobin concentration (total, oxy– and deoxy– forms), oxygen saturation and water concentration. We present preliminary results of non–invasive FDPM measurements obtained from normal and tumour–containing human breast tissue. Our data clearly demonstrate that physiological changes caused by the presence of small (about 1 cm diameter) palpable lesions can be detected using a handheld FDPM probe.
The epidemiology of BSE in cattle herds in Great Britain. I. Epidemiological processes, demography of cattle and approaches to control by culling
Authors: Donnelly C. A. , Ferguson N. M. , Ghani A. C. , Woolhouse M. E. J. , Watt C. J. , Anderson R. M.
Published: October 2002

This paper explores the key epidemiological processes and demographic factors that determined the pattern of transmission of the aetiological agent of bovine spongiform encephalopathy (BSE) in cattle herds in Great Britain (GB). The analyses presented utilize data from published and unpublished experimental studies and from the GB central database of confirmed BSE cases.

We review the experimental and epidemiological evidence that has both confirmed indirect horizontal transmission via the consumption of infectious material as the major transmission route and provided information on the duration and variability of the dose–dependent incubation period of BSE in cattle. The epidemiological and genetic data pertaining to the possible existence of maternal transmission and/or genetically variable susceptibility to infection is discussed.

The demography of British cattle is characterized and the impacts of key demographic features on the observed epidemic profile are discussed. In the main BSE case database, analyses reveal that BSE cases cluster significantly at both the holding and county scale. Furthermore, analysis of longitudinal patterns reveal substantial temporal within–holding correlation. Such clustering of cases suggests a highly heterogeneous infection process.

The paper ends with a discussion of how analyses of spatio–temporal clustering inform the design of targeted culling programmes aimed at reducing future disease incidence. We show how the retrospective implementation of culling policies on the BSE case database allows the qualitative evaluation of policy performance, but that model predictions of future trends in case incidence are required to estimate the precise impact of any current or future programme.